Feline Dentistry: Oral Assessment, Treatment, and Preventative Care

FELINE DENTISTRY Oral Assessment, Treatment, and Preventative Care

FELINE DENTISTRY Oral Assessment, Treatment, and Preventative Care Jan Bellows

A John Wiley & Sons, Inc., Publication

Edition first published 2010 © 2010 Jan Bellows Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing program has been merged with Wiley’s global Scientific, Technical, and Medical business to form Wiley-Blackwell.

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Bellows, Jan. Feline dentistry : oral assessment, treatment, and preventative care / Jan Bellows. p. ; cm. Includes bibliographical references and index. ISBN 978-0-8138-1613-5 (hardback : alk. paper) 1. Veterinary dentistry. 2. Cats–Diseases. I. Title. [DNLM: 1. Tooth Diseases–veterinary. 2. Cats. 3. Dental Care–veterinary. 4. Mouth Diseases–veterinary. SF 867 B448f 2010] SF867.B447 2010 636.8′08976–dc22 2009031848 A catalog record for this book is available from the U.S. Library of Congress. Set in 9.5/12 pt Palatino by Toppan Best-set Premedia Limited Printed in Singapore 1

2010

Dedication

This text is dedicated to Dr. Colin E. Harvey Throughout his professional life, Dr. Colin Harvey has taught and mentored others while creating and maintaining the foundation of veterinary dentistry in the United States and around the world. Dr. Harvey graduated from the School of Veterinary Science at the University of Bristol, England, in 1966. He completed an internship and residency in small animal surgery at the University of Pennsylvania, receiving the Diploma of the American College of Veterinary Surgeons in 1972. Dr. Harvey is a diplomate of the American College of Veterinary Surgeons (1972), member of the Organizing Committee and charter diplomate of the American Veterinary Dental College (AVDC, 1988) and the European Veterinary Dental College (1998), and also a charter diplomate of the European College of Veterinary Surgeons (1993). He was section chief of Small Animal Surgery (1974–80) and vice-chair of the Department of Clinical Studies (1996–2002) and was the founding head of the Dentistry and Oral Surgery Service at the University of Pennsylvania (the first dentistry and oral surgery service to be established at a veterinary school in North America). Dr. Harvey has received numerous university, national, and international awards for excellence in teaching, research, and clinical work. He was elected a fellow of the College of Physicians of Philadelphia in 1980. Dr. Harvey has been a board member (1978–83) of

the Comparative Respiratory Society, secretary (1985– 89) of the American Veterinary Dental Society, president (1990–92) and executive secretary (2002–present) of the American Veterinary Dental College, cofounder (1985) of the International Veterinary Ear Nose and Throat Association, charter fellow and secretary-treasurer (1987–89) of the Academy of Veterinary Dentistry, and director (1997–present) of the Veterinary Oral Health Council. Dr. Harvey was editor of the Journal of Veterinary Surgery from 1982 to 1987 and editor of the Journal of Veterinary Dentistry from 1994 to 2000 and has been a reviewer or review board member for numerous other journals. His publications include approximately 70 chapters in textbooks, 130 papers in peer-reviewed journals, and over 100 abstracts and other papers on surgical and dental topics. He has written, edited, or coedited five books on small animal surgery and dentistry. Dr. Harvey’s research interests include veterinary and comparative periodontal disease (including comparative microbiology, standardization of periodontal scoring, and prevention and treatment); the interaction of infectious oral diseases, particularly periodontal disease, with the rest of the body, specifically, distant organ and systemic effects; and the utility and effectiveness of antimicrobial drugs in the management of patients with oral diseases. Feline dentistry has been of special interest to Dr. Harvey. Much of what we know about feline dentistry today is largely due to his and his mentees’ uncompromised research and discovery efforts.

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Contents

Preface, viii Acknowledgments, ix Introduction, x Section I.

Oral Assessment, 3

Chapter 1.

Anatomy, 5

Chapter 2.

Oral Examination, 28

Chapter 3.

Radiology, 39

Chapter 4.

Charting, 84

Chapter 5.

Oral Pathology, 101

Section II.

Treatment, 149

Chapter 6.

Equipment, 151

Chapter 7.

Anesthesia, 169

Chapter 8.

Treatment of Periodontal Disease, 181

Chapter 9.

Treatment of Endodontic Disease, 196

Chapter 10. Treatment of Tooth Resorption, 222 Chapter 11. Treatment of Oropharyngeal Inflammation, 242 Chapter 12. Treatment of Occlusion Disorders, 269 Chapter 13. Oral Trauma Surgery, 280 Chapter 14. Treatment of Oral Swellings/Tumors, 290 Section III. Prevention, 297 Chapter 15. Plaque Control, 299 Index, 305

vii

Preface

Ah, Cats. What would veterinary dentistry be without them! For sure, a lot simpler and less frustrating. Even for procedures so apparently “simple” as a tooth extraction, the cat often has the last word, when we as veterinary dentists hear that quiet but awful ‘snick’ that means that a tooth root has fractured, leaving a root tip somewhere down there. … Since the first-reported mention of oral disease in cats in the 1920s, a lot of progress has been made, but some key knowledge is not yet available. The immunological function of the cat does not seem to obey the same rules as rodents, dogs, and humans; and as a result, immunologically based conditions such as stomatitis continue to frustrate veterinary dentists. Teeth in cats are attacked

viii

by the body’s own tissues for reasons that are still not clear, and our frustrations are heightened by the lack of success of restoring feline teeth undergoing resorption. Squamous cell carcinoma is by far the most common feline oral neoplasm, benign or malignant; and it resists all standard treatments used in management of other malignancies. When we add in that anesthesia is essential for all feline dental procedures (lest our fingers be impaled by the needle-like, plaque-coated canine teeth) and that cats have such a little mouth compared with dogs, it is not surprising that there is some love-hate aspect to the relationship of veterinary dentists to cats. The challenge is one to rise to, and the companionship cats offer makes it all worthwhile. A book dedicated to feline dentistry and related topics is overdue. I am pleased that Dr. Bellows has found the time to pull the material together in a coherent format, so that others may build upon the accumulated experience and knowledge that are described here. Those delicate feline oral structures require all the skill and knowledge that we have and deserve our best efforts to ensure that we are not continuously restarting the steepslope part of the learning curve. Colin E. Harvey

Acknowledgments

The author acknowledges and greatly appreciates the selfless efforts of many in the production of this text. First to my wife Allison who has always supported and encouraged my passion to do the best for my patients and help other veterinarians do their best too. Next my children Wendi, David, and Lauren who have helped in the practice and have been there every step of the journey. Dr. Carlos Rice, currently a dental resident at University of Wisconsin, on a four-month volunteer stint at All Pets Dental in Weston helped catalog thousands of images from our client base to be considered for inclusion in this text. Dr. Rice also reviewed the final text. Dr. Gary Edelson also volunteered to review the text word by word multiple times. His attention to detail is much appreciated. Drs. Gregg DuPont and Alex Reiter reviewed every word and image in this text. They are expert veterinary dentists with decades of teaching and practical experience. Both share a passion for the best in companion animal dental care based on solid peer-reviewed information where available. Their input resulted in the work you have before you.

Additionally, I acknowledge the American Veterinary Dental College (AVDC) in their efforts to “get things right.” I have had the pleasure and honor of being a member and chairman of the college’s nomenclature committee since 2004, during which time the college has improved classifications for tooth resorption stages and types, fractures, periodontal disease, and many anatomical terms. I acknowledge and thank Dr. Paul Pion, the originator of the Veterinary Information Network (VIN). Dr. Pion strives to improve the veterinary community on all levels. Through the give and take on VIN’s message forums, we learn from each other. I also thank Dr. Pion for the use of his talented full-time graphic artist, Tamara Rees, who provided illustrations for the AVDC and this text. Finally, I can’t say enough about the publisher of this text, Wiley-Blackwell. Working with Nancy Simmerman, the Editorial Assistant, has been a pleasure from our initial discussions, in early 2006, throughout the process to the final submission of the manuscript.

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Introduction

Cats are not dogs. Small dogs are plagued primarily with various degrees of periodontal disease (gingivitis and periodontitis). Large dogs more commonly present with gingivitis, fractured teeth, and oral masses. Feline Dentistry: Oral Assessment, Treatment, and Preventative Care was born primarily to give cats their fair due, a book on dentistry dedicated solely to their species. Cats also are affected by periodontal disease and fractured teeth, but their main oral pathologies include tooth resorption, oropharangyeal inflammation, and maxillofacial cancer. Plaque prevention products and techniques covered in this text also differ from those used in dogs. The second goal in writing this text is to introduce to some and reinforce to others the paradigm shift eliminating the terminology “doing a dentistry,” “performing a prophy,” or “Max is in for a dental.” Replacing the old terminology with “oral assessment, treatment, and prevention,” better represents what we do as veterinary dentists. Assessment involves evaluation of the patient before the anesthetic procedure and includes medical and dental history, feeding management, home oral hygiene, and physical and laboratory testing. Once the patient is anesthetized, a tooth-by-tooth examination is conducted to create a treatment plan. Treatment with the goal of eliminating non-functional abnormalities uncovered during assessment is next. The treatment plan often can be accomplished within one anesthetic visit. In some instances, multiple visits or lifelong therapy are indicated. Prevention of periodontal disease is aimed at controlling plaque. Prevention is as important as the assessment and treatment steps. Without prevention, there is

x

little doubt that periodontal disease will either continue or worsen. Plaque control methods must be specifically tailored to the patient and client in order to be effective. Through daily use of the oral assessment, treatment, and prevention process, patients can get the best in veterinary dentistry, which is our ultimate goal. Although a genuine effort has been made to assure that the dosages and information included in this text are correct, errors may occur, and it is recommended that the reader refer to the original reference or the approved labeling information of the product for additional information. Dosages should be confirmed prior to use or dispensing of medications. Jan Bellows, D.V.M. Diplomate, American Veterinary Dental College Fellow, Academy Veterinary Dentistry Diplomate, American Board of Veterinary Practitioners

FELINE DENTISTRY Oral Assessment, Treatment, and Preventative Care

Section I

Oral Assessment

Chapter 1

Anatomy

An understanding and appreciation of feline dental pathology, treatment, and prevention requires a deep awareness of the structure and function of oral tissues that are composed of the teeth and supporting tissues.

Oral Cavity The oral cavity extends from the lips to the pharynx, bounded laterally by the cheeks, dorsally by the palate, and ventrally by the tongue and intermandibular tissues. The oral cavity is divided into the oral cavity proper and the oral vestibule. Within the oral cavity proper are the hard palate, soft palate, tongue, and the floor of the mouth. Caudally, the oral cavity proper ends at the palatoglossal folds. The oral vestibule spans between the lips, cheeks, and dental arches. The labial vestibule is the space between the incisors, canines, and lips. The buccal vestibule is the space between the cheek teeth and the cheeks (figs. 1.1 a–g).

Mucosa Oral mucosa covers the surface of the mouth. The outer layer is composed of variably pigmented nonkeratinized and parakeratinized stratified squamous epithelium. The submucosa is composed of loose connective tissue, salivary glands, blood vessels, muscle fibers, lymphatics, and salivary ducts. The submucosa of the palate is composed of dense collagen.

Muscles The muscles of mastication that close the jaws are the temporal, masseter, and medial and lateral pterygoid muscles, all of which are innervated by the mandibular nerve (the only motor branch of the trigeminal nerve). The digastricus muscle opens the mouth. Its rostral belly is innervated by the mandibular branch of the trigeminal nerve, while its caudal belly is innervated by the facial

nerve. The body (the rostral two-thirds) of the tongue is attached ventrally to the midline of the floor of the mouth by the lingual frenulum.

Tongue The tongue has important functions in grooming, eating, drinking, and vocalization. The tongue is composed of both striated intrinsic and extrinsic muscles. The body of the tongue comprises the rostral two-thirds. The root comprises the caudal one-third and is attached to the hyoid apparatus. The dorsal surface of the tongue is covered by keratinized stratified squamous epithelium that forms papillae. The tongue of a cat is populated by filiform, fungiform, vallate, foliate, and conical papillae. Filiform and fungiform papillae occupy the dorsal surface of the tongue body. Vallate papillae separate the tongue body and root dorsally. Vallate, foliate, and conical papillae occupy the tongue root (figs. 1.2 a, b). Pillars of mucosa and the palatoglossal folds extend to the soft palate at the base of the tongue (fig. 1.3). The ventral tongue surface contains less cornified mucosa. The lingual frenulum connects the tongue to the floor of the mouth within the intermandibular space.

Innervation Sensory input is received from maxillary and mandibular divisions of the trigeminal nerve. The maxillary branch leaves the trigeminal ganglion, then exits the cranial cavity through the foramen rotundum, courses through the alar canal and the pterygopalatine fossa to enter the infraorbital canal. Just before entering the caudal limit of the infraorbital canal, the nerve branches to become the major and minor palatine nerves. These nerves innervate the hard and soft palates and the nasopharynx. The palatine nerves are desensitized with the maxillary nerve block. 5

d

a

e

b

f

c

6

Figure 1.1 a–g Mucosal surfaces of the oral cavity (all images © 2009 Dr. Alexander M. Reiter).

g Figure 1.1 Continued

Figure 1.3

Palatoglossal fold inflammation.

b

a Figure 1.2

a. Tongue and papillae 1. Filiform papillae; 2. Fungiform papillae; 3. Foliate papillae; 4. Vallate papillae. b. Filiform papillae.

7

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Feline Dentistry

The maxillary branch of the trigeminal nerve also gives off the caudal maxillary alveolar nerve, which innervates the maxillary first molar, the buccal gingiva, and mucosa. This area is blocked with the infraorbital nerve block. After giving off the caudal maxillary alveolar nerve, the maxillary nerve enters the infraorbital canal, where it is called the infraorbital nerve. While the infraorbital nerve is traversing the infraorbital canal, it gives off two more branches that exit ventrally from the canal. The middle maxillary alveolar nerve innervates the premolars and associated buccal gingiva. The rostral maxillary alveolar nerve supplies the canines, incisors, and associated buccal gingiva. The remaining fibers of the infraorbital nerve then exit the rostral extent of the infraorbital canal to innervate the lateral and dorsal cutaneous structures of the rostral maxilla and upper lip. The middle maxillary alveolar, rostral maxillary alveolar, and the infraorbital nerves are anesthetized by the rostral infraorbital nerve block. The mandibular division of the trigeminal nerve arises from the trigeminal ganglion, exits the cranium via the foramen ovale, and divides into multiple branches. The divisions include the sensory buccal nerves, lingual nerve, and mandibular (inferior alveolar) nerve. The buccal nerves receive stimuli from the facial musculature, skin and mucosa of the cheek, and buccal gingiva along the caudal mandible. The hypoglossal nerve innervates the tongue, the floor of the mouth, the lingual gingiva, and the mandibular salivary gland. The mandibular nerve enters the mandible on the lingual side, via the mandibular foramen. The nerve then courses rostrally within the mandibular canal to innervate the mandibular teeth to the midline. This nerve can be blocked with the mandibular (inferior alveolar) nerve block. Rostral to the third premolar tooth, the mandibular nerve gives off mental nerve branches. These branches exit through the mental foramina (rostral, middle, and caudal) and innervate the cutaneous areas of the chin and lip, and the rostral buccal gingiva and mucosa. These nerves are blocked with the mental nerve blocks (usually the middle mental nerve is blocked).

Blood Supply and Lymphatic Drainage The external carotid arteries branch off to the maxillary arteries. They further supply the mandibular (inferior alveolar) arteries, which enter the mandibular foramina on the medial sides of the mandibles and then course rostrally in the mandibular canals, where they exit through the mental foramina.

The maxillary arteries also give rise to the major palatine arteries, which anastomose with the infraorbital arteries. The infraorbital arteries exit at the infraorbital foraminae to supply the rostral muzzle. Lymph from the oral cavity drains into the parotid, mandibular, lateral, and medial retropharyngeal, superficial, and deep cervical lymph nodes.

Salivary Glands The major salivary glands in the cat include the parotid, zygomatic, mandibular, and sublingual. Saliva from the parotid gland exits at a papilla in the alveolar mucosa, just caudal to the maxillary fourth premolar. Saliva from the zygomatic gland exits at a papilla in the alveolar mucosa near the maxillary first molar. Saliva from the mandibular and sublingual glands enters the oral cavity through the sublingual caruncles located ventral and rostral to the base of the tongue (figs. 1.4 a, b). Cats have four molar salivary glands. The buccal molar glands empty into the oral cavity through several small ducts. The lingual molar glands are located in the membranous molar pad linguodistal to the mandibular first molar teeth (fig. 1.5).

Periodontium The term periodontium is used to describe tissues that surround and support the teeth, including the gingiva, periodontal ligament, cementum, and alveolar bone.

Gingiva The cat’s oral cavity is lined with keratinized and nonkeratinized stratified squamous epithelium. Gingiva refers to the keratinized oral mucosa that covers the alveolar process and surrounds the cervical portion of the tooth crowns. Unlike the epithelial lining of the digestive tract, the gingiva does not have absorptive capacity but acts as a physiologic permeable barrier that protects underlying structures (fig. 1.6). The gingival epithelium is composed of the following:

•

•

The oral epithelium, also called the outer gingival epithelium, which is keratinized or parakeratinized and covers the oral surface of the attached gingiva and gingival papillae. The sulcular epithelium is a nonkeratinized extension of the oral epithelium into the gingival sulcus. The bottom of the gingival sulcus in a periodontally

Anatomy

9

Figure 1.5 Membranous bulge linguodistal to the mandibular first molar tooth containing a minor salivary gland (lingual molar gland).

a

b Figure 1.4

•

a and b. Sublingual caruncle.

healthy tooth should be slightly coronal to the cementoenamel junction. The junctional epithelium attaches to enamel of the most apical portion of the crown by means of hemidesmosomes and lies at the floor of the sulcus, immediately coronal to or at the cementoenamel junction. The junctional epithelium and gingival connective tissue separate the periodontal ligament from the oral environment. The floor of the gingival sulcus is located on the most coronal junctional epithelial cells.

Marginal gingiva is the most coronal (toward the crown) aspect of the gingiva that is not attached to the

Figure 1.6 Oral mucosa in a patient with gingivitis, periodontitis, and caudal mucositis.

tooth but lies passively against it. When healthy, it appears coral-pink, firm, and with knife-edged margins. Pigment may or may not be normally present. The space between the tooth and the marginal gingiva is the gingival sulcus (or crevice). The normal depth of the sulcus is less than 1 mm in cats. The free gingival margin is the coronal edge of the marginal gingiva. Marginal gingiva is demarcated from

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Feline Dentistry

Figure 1.7 Gingival structures surrounding the left maxillary fourth premolar.

the attached gingiva by the gingival groove, a slight depression on the gingiva corresponding to the normal sulcus depth (fig. 1.7). In the cat, the healthy free gingival margin of premolars and molars lies between 0.5 and 1 mm coronal to the cementoenamel junction, where root cementum meets crown enamel. The attached gingiva is located apical to the marginal gingiva and is normally tightly bound to the periosteum of alveolar bone. Attached gingiva is keratinized to withstand the stress of mastication. The width of the attached gingiva varies in different areas of the mouth. The attached gingiva is widest at the maxillary canines. The firmly attached gingiva is contiguous with loose alveolar mucosa at the mucogingival junction, also referred as the mucogingival line. The mucogingival junction remains stationary throughout life, although the gingiva around it may change in height due to attachment loss (figs. 1.8 a, b). The gingival sulcus is a shallow space between the marginal gingiva and the tooth. The sulcus depth is generally under 1 mm but varies depending on the specific tooth and the size of the cat. In cases of periodontal disease, the abnormal sulcus is termed a pocket, which extends further apically due to destruction of the periodontium (figs. 1.9 a, b).

Periodontal Ligament The periodontal ligament is a dense, fibrous connective tissue that attaches the tooth root to the bony alveolus. The periodontal ligament also acts as a suspensory cushion against occlusal forces and as an epithelial attachment to keep debris from entering deeper tissues. The blood supply to the periodontal ligament originates from the alveolar artery. Arterioles enter the liga-

ment near the apex of the root and from lateral aspects of the alveolar socket and branch into capillaries within the ligament along the long axis of the tooth. Collagen fibers also run through these spaces. The blood vessels are closer to the bone than to the cementum. Venules drain the apex through apertures in the bony wall of the alveolus and into the marrow spaces. Nerve bundles enter the periodontal ligament through numerous foramina in the alveolar bone. They branch and end in small rounded bodies near the cementum. The nerves carry pain, touch, and pressure sensations and form an important part of the feedback mechanism of the masticatory apparatus. The periodontal ligament has great adaptive capacity. It responds to chronic functional overload by widening to relieve the load on the tooth. Vascular communications between the pulp and periodontium form pathways for transmission of inflammation and microorganisms between the tissues.

Cementum Cementum covers the root and provides attachment for the periodontal ligament. Cementum is produced continuously, slightly increasing in thickness throughout life. Acellular cementum is present at the coronal onethird of the root. Cellular cementum is present at the apical two-thirds of the root. It is capable of formation, destruction, and repair. It is avascular but is nourished from vessels within the periodontal ligament. Cementocytes in cellular cementum communicate with each other via canaliculi and with underlying dentin.

Alveolar Bone Alveolar processes house the alveoli, which support the teeth by providing attachment for fibers of the periodontal ligament. An alveolus can be divided into two parts: 1.

2.

Alveolar bone proper, which is a thin layer of bone surrounding the root and allowing attachment to the periodontal ligament. Supporting alveolar bone, which consists of compact, cortical, or cancellous bone on the vestibular and oral aspects of the alveolar process.

The alveolar bone and cortical plates are thickest in the mandible. The shape and structure of the trabeculae of spongy bone reflect the stress-bearing requirements of a particular site. In some areas, alveolar bone is thin with no spongy bone. The alveolar bone proper is also referred to as the cribriform plate and is identified on radiographs as lamina dura (fig. 1.10). The alveolar bone height is an equilibrium between bone formation and bone resorption. When bone

a

b Figure 1.8

a. Gingival structures surrounding the right maxillary cheek teeth. b. Mandibular fourth premolar area.

11

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Feline Dentistry

a Figure 1.9

b a. Periodontal probe with millimeter markings before insertion. b. 3-mm palatal probing depth of the left maxillary canine.

resorption exceeds formation, the alveolar bone height is reduced (figs. 1.11 a, b).

Bones and Joints Cranium The dorsal aspect of the cranium is composed of the paired frontal and parietal bones. The occipital region of the cranium is the caudal aspect of the skull formed by the occipital bone. The temporal region is composed of the lateral walls of the cranium formed by the temporal bones. The rostral wall of the cranium is formed by the ethmoid bone (figs. 1.12 a, b).

Facium

Figure 1.10 Lamina dura (arrows pointing to the white line surrounding the tooth root).

The facial part of the skull, which encloses the nasal and oral cavities, is divided into oral, nasal, and orbital regions. The oral region surrounding the oral cavity is composed of the incisive, maxillary, palatine, and mandibular bones. The region surrounding the nasal cavity is composed of the nasal, maxillary, palatine, and incisive bones. The orbital region is formed by the frontal, lacrimal, palatine,

a Figure 1.11

b a. Alveolus encasing a fractured maxillary canine tooth. b. Decreased alveolar margin height (arrows) secondary to periodontal disease.

Figure 1.12 a. Left lateral aspect of the skull with the zygomatic arch removed; 1. Parietal bone; 2. Squamous temporal bone; 3. Sphenopalatine foramen; 4. Maxilla; 5. Incisive bone; 6. Frontal bone; 7. Lacrimal bone; 8. Optic canal. b. Medial aspect of a sagittal section of the left aspect of the skull: 1. Incisive bone; 2. Maxilloturbinates; 3. Nasal bone; 4. Nasal septum; 5. Palatine bone; 6. Pterygoid bone; 7. Ethmoid bone. c. Dorsal aspect of the skull: 1. Incisive bone; 2. Nasal bone; 3. Maxilla; 4. Frontal bone; 5. Zygomatic process of frontal bone; 6. Zygomatic bone; 7. Parietal bone; 8. Zygomatic process of temporal bone; 9. Lacrimal foramen; 10. Infraorbital foramen. d. Ventral aspect of the skull: 1. Incisive bone; 2. Palatine process of the maxilla; 3. Major palatine foramen; 4. Vomer bone; 5. Pterygoid bone; 6. Frontal bone; 7. Palatine bone; 8. Temporal process of the zygomatic bone; 9. Zygomatic process of the temporal bone; 10. Retroarticular process; 11. Mandibular fossa of the articular surface of the temporomandibular joint. (Images reprinted with permission of Morton Publishing Company.)

a

b 13

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Feline Dentistry

c

d

Figure 1.12 Continued

sphenoid, and zygomatic bones surrounding the orbit (figs. 1.12 c, d).

Maxillary Region The maxillary bones or maxillae form the lateral parts of the face and the part of the hard palate that holds the canine and upper cheek teeth. The maxilla articulates with the incisive bone rostrally, the nasal bone dorsally, the vomer bone medially, and the lacrimal and zygomatic bones caudally (figs. 1.13 a, b). The palatine bone forms the bony part of the hard palate together with the maxillary and incisive bones. The incisive bone located rostrally holds the upper incisors. A pair of openings, the palatine fissures, allows passage of the incisive ducts of the vomeronasal organ. The incisive papilla located just caudal to the maxillary first incisor teeth houses these incisive ducts as they open into the oral cavity (figs. 1.14 a, b). The hard palate separates the oral and nasal cavities. The primary palate is the incisive portion of the palate and associated soft tissues. The secondary palate includes the remaining hard and soft palatal structures. Firmly

attached, heavily keratinized mucosa covers the hard palate. Seven to eight transverse ridges called rugae protrude from the mucosa with rows of papillae between the ridges. The soft palate begins caudal to the maxillary first molar teeth and separates the nasopharynx dorsally and oropharynx ventrally (figs. 1.15 a, b). The infraorbital canal is located apical to the maxillary third and fourth premolars below the orbit. Compared to the dog, the cat’s infraorbital canal is shorter and usually less than five millimeters in diameter.

Mandibles The large bones articulating with the skull that support the lower teeth are the mandibles. Each mandible is composed of a horizontal body and a vertical ramus. The body supports the lower teeth. The ramus has three processes: coronoid, condylar, and angular. The condylar process articulates with the cranium in the temporomandibular joint (figs. 1.16 a–c). The mandibles are connected to each other by a strong fibrocartilaginous joint at the mandibular symphysis. The nerves and vascular supply to the mandibular teeth

Anatomy

15

a

a

b Figure 1.14

a. Palatine fissures. b. Incisive papilla.

Temporomandibular Joint

b Figure 1.13 a. Lateral aspect of right maxilla: 1. Alveolar process; 2. Frontal process; 3. Infraorbital canal; 4. Zygomatic process. b. Medial aspect of the right maxilla: 1. Maxillotubinates; 2. Palatine process.

The head of the condylar process of the mandibular ramus articulates with the base of the zygomatic process of the squamous part of the temporal bone (mandibular fossa) at the temporomandibular joint: a transversely elongated (cigar-shaped), condylar, synovial joint (fig. 1.18). The retroarticular process is a caudoventral extension of the mandibular fossa. The retoarticular process helps prevent caudal luxation of the mandible (fig. 1.19). The insertion of the masseter muscle reaches the ventral and rostral aspect of the joint capsule. There is a thin, cartilaginous intra-articular disc dividing the joint into dorsal and ventral compartments. This disc reduces friction by providing a double synovial film.

Teeth enter the mandibular canal ventrally on the lingual aspect of the angle of the mandible and course rostrally exiting at the caudal, middle, and rostral mental foramina to supply the rostral mandible, chin, lip, buccal gingiva, and mucosa (figs. 1.17 a–c). The tongue and some of the muscles of the hyoid apparatus occupy the intermandibular space.

Dental Formula Normally, there are twenty-six deciduous and thirty permanent teeth in the cat’s oral cavity. Dental formulas (upper number indicates the maxillary teeth, lower number the mandibular teeth) are as follows:

a

b

16

Figure 1.15 a. Sagittal section of dissected head: 1. Choana; 2. Nasopharynx; 3. Epiglottis; 4. Palatine tonsil in tonsilar fossa; 5. Oropharynx; 6. Oral cavity; 7. Hard palate b. Roof of the oral cavity, 1. Hard palate, 2. Palatine rugae, 3. Palatine tonsil, 4. Stick in nasopharynx, 5. Epiglottis (reflected laterally) 6. Palatoglossal arch, 7. Soft palate.

a

b

Figure 1.16 a. Lower jaw. b. Right mandible buccal aspect: 1. Mandibular body; 2. Mandibular ramus; 3. Masseteric fossa; 4. Coronoid process; 5. Condyloid process; 6. Angular process; 7. Middle mental foramen; 8. Caudal mental foramen. c. Right mandible lingual aspect: 1. Mandibular symphysis articular surface; 2. Mandibular foramen.

c

a

b

c

Figure 1.17 a. Mandibular symphysis dorsal view. b. Mandibular symphysis rostral view showing the mental foramina (arrows). c. Mental foramina.

17

Figure 1.18 Temporomandibular joints ventral view: 1. Retroarticular process; 2. Mandibular fossa; 3. Condylar process; 4. Angular process.

Figure 1.19 Lateral aspect of the left temporomandibular joint: 1. Coronoid process; 2. Zygomatic arch; 3. Zygomatic process of the temporal bone; 4. Mandibular ramus; 5. Condylar process; 6. Articular eminence; 7. Tympanic bulla; 8. Mandibular fossa; 9. Retroarticular process; 10. Angular process.

18

Anatomy

• •

The deciduous dental formula for kittens is 2 × (I3/ I3, C1/C1, P3/P2) = 26 teeth. The permanent dental formula for adult cats is 2 × (I3/I3, C1/C1, P3/P2, M1/M1) = 30 teeth.

All of the incisors and canine teeth have one root. The maxillary second premolar, if present, normally has one root; however, studies have shown nearly 40% of the maxillary second premolars have two (sometimes fused) roots. The maxillary third premolar has two roots in most cases (10% of the maxillary third premolars have a small third root), and the maxillary fourth premolars have three roots. The maxillary first molars, if present, usually have two roots. The mandibular cheek teeth in a cat (third and fourth premolars and first molars) have two roots.

Tooth Types Teeth are categorized by location and form. There are four types of teeth in the cat:

Figure 1.20

Maxillary and mandibular incisors.

19

Incisors are small teeth located between the canines. They are used for prehension. Incisors are referred to as right/left, maxillary/mandibular, first, second, and third incisors (fig. 1.20). When using the modified Triadan system, right maxillary incisors are numbered 101, 102, and 103 starting from the first incisor, and left maxillary incisors are numbered 201, 202, and 203. The left mandibular incisors are numbered 301, 302, 303, and the right mandibular incisors are 401, 402, 403 (fig. 1.21). Canines are single-rooted teeth located rostrally in the mouth caudolateral to the incisors. They are used for piercing and biting. Canines are referred to as right/left, maxillary/mandibular canines. The crowns of the maxillary and mandibular canine teeth have vertical grooves (figs. 1.22, 1.23). When using the modified Triadan system, the right and left maxillary canines are numbered 104 and 204, respectively. The root and crown of the maxillary canines help to hold the upper lip outward, so that when the mouth is closed, the coronal tip of the mandibular canine

Figure 1.21 Modified Triadan system incisor tooth numbering.

Figure 1.23

Figure 1.22 Extracted canine tooth.

20

Mandibular canine vertical groove.

Anatomy

slides into the vestibule without traumatizing the upper lip. The left and right mandibular canines are numbered 304 and 404, respectively (in the modified Triadan system, all the canines end in 4 and first molars in 9) (figs. 1.24 a, b; 1.25).

a

Premolars are located caudal to the canines. There are normally three maxillary and two mandibular premolars in the cat. Proper nomenclature of feline premolars is based on the archetypal carnivore model, which has a full dentition of forty-four teeth (six incisors, four canines, sixteen premolars, and twelve molars). The premolar behind the maxillary canine is termed the right or left maxillary second premolar (fig. 1.26). Using the modified Triadan system, the second premolars are referred to as tooth 106 (right) or 206 (left). The second premolar has one or two fused roots. The third premolars (107, 207) have two roots. The fourth premolars (108, 208) have three roots (mesiobuccal, mesiopalatal, and distal)(fig. 1.27). The premolar behind the mandibular canine is termed the left or right mandibular third premolar (307, 407),

b Figure 1.24 Modified Triadan canine tooth numbering: a. Maxillary canines. b. Mandibular canines.

Figure 1.25

21

Figure 1.26

Maxillary premolars.

Figure 1.27

Maxillary fourth premolar.

Normal canine tooth occlusion.

22

Feline Dentistry

followed by the fourth premolar (308, 408), which has two roots (figs. 1.28 a, b). Molars are located caudal to the premolars. There is one set in the maxilla termed right or left maxillary first molar (109, 209) and one set in the mandible termed left or right mandibular first molar (309, 409). The mandibular first molar has one large mesial root and a smaller distal root, which angles caudally (figs. 1.29, 1.30 a–d).

Tooth Composition The exterior surface of the healthy crown is covered with a thin layer of enamel, a hard inorganic substance (96% inorganic) formed by ameloblasts within the tooth bud before eruption. Enamel when damaged is incapable of repair once the tooth has erupted. Dentin located beneath the enamel and cementum composes the majority of the mature tooth mass. Dentin is a specialized connective tissue of mesenchymal origin and is the second hardest tissue in the body after enamel. It is 70% inorganic and 30% organic (water, collagen, and mucopolysaccharide).

Dentin is porous; each square millimeter contains over 40,000 dentinal tubules that communicate between the pulp and the dentin-enamel or dentin-cementum junctions. If there is near-pulp exposure from trauma or resorption, bacteria can travel through the exposed dentinal tubules to the pulp. Near exposure can also transmit painful stimuli (heat, cold, pressure) from the oral environment to the pulp. In cats and other species including the dog, two microscopic features of the dentin known as vasodentin and osteodentin may occasionally exist. Vasodentin is characterized by microscopic vascular inclusions within the outer third of the dentin. It is found to have vascular channels and dentinal tubules coursing through vasodentin randomly. Osteodentin, unlike vasodentin, is most often found in the dentin adjacent to the root canal. Previous studies have demonstrated the presence of these two peculiar microscopic structures in cats with tooth resorption. However, vasodentin and osteodentin have also been found in teeth free of resorption, making a cause-and-effect relationship difficult to confirm. The pulp, located in the center of the tooth, is composed of connective tissue, nerves, lymph and blood vessels, collagen, and odontoblasts, which form dentin throughout the tooth’s life. The pulp cavity consists of a pulp chamber located in the crown and a root canal in

a

b Figure 1.28 a. Teeth of the lower jaw. b. Right mandibular premolars.

Figure 1.29

Dissected left mandibular first molar.

Anatomy

23

b

a

c

d Figure 1.30 a. Modified Triadan system numbering of teeth in the upper jaw. b–d. Modified Triadan system numbering of teeth in the lower jaw.

the root. In a fully mature tooth, an apical delta containing minute openings allowing the passage of vessels and nerves is present at the root apex. Occasionally, there are communication canals present at the furcation of the maxillary fourth premolar and other multirooted teeth (fig. 1.31). During pre-eruptive development and during eruption, the odontoblasts produce primary dentin. Once the

tooth has developed to its final length, the odontoblasts produce secondary dentin, causing the dentinal walls to thicken toward the pulp cavity. This will effectively decrease the width of the pulp cavity as the cat ages. Reparative or tertiary dentin is produced in response to thermal, mechanical, occlusal, or chemical trauma to the odontoblasts. The pulp chamber in cats lies closer to the enamel than in dogs. For this reason, any tooth fracture

24

Feline Dentistry

Figure 1.31 Illustration of sagittal section through the canine tooth.

in the cat should be treated aggressively, since most require endodontic therapy or extraction. Odontoblast processes extend into the dentinal tubules. These processes, together with the fine nerve endings, cause the dentin to be sensitive to temperature and pressure. When traumatized, the pulp reacts to irritants through inflammation. If untreated, severe inflammation spreads up and/or down the pulp, eventually becoming irreversible. Toxic products from damaged tissue and microorganisms in the tissue sustain inflammation. The tooth’s anatomical crown is visible to the naked eye. The root is located in the alveolus encased in the alveolar processes beneath the gingiva. The cribriform plate (lamina dura) lines the alveolus (fig. 1.32).

Tooth Eruption The maxillary teeth generally erupt before their mandibular counterparts. Eruption of the incisors precedes that of the canines, which is later followed by the premolars and molars.

The deciduous tooth eruption is normally complete by two months of age. By seven months, the permanent teeth should be fully erupted (Table 1.1).

Terminology Teeth Incisors are referred to as the (right or left, maxillary or mandibular) first, second, or third incisors numbered from the midline. In the cat, the tooth immediately distal to the maxillary canine is the second premolar; the tooth immediately distal to the mandibular canine is the third premolar.

Surfaces of teeth and directions in the mouth (fig. 1.33) Vestibular is the correct term referring to the surface of the tooth facing the vestibule or lips; buccal and labial are acceptable alternatives.

Anatomy

25

Apical delta Alveolar process Lamina dura Trabecular bone Cortical plate

Periodontal ligament

Cementum

Alveolar mucosa Alveoler crest

Mucogingival line

Gingival margin

Attached gingiva Free gingiva Gingival sulcus

Epithelial attachment

Dentin Pulp

Enamel

Figure 1.32

Canine tooth and surrounding structures.

Table 1.1. Approximate age when teeth erupt (in weeks).

Incisors Canine Premolar Molar

Deciduous

Permanent

3–4 3–4 5–6

11–16 12–20 16–20 20–24

The surface of a mandibular or maxillary tooth facing the tongue is the lingual surface. Palatal can also be used when referring to the lingual surface of maxillary teeth. Mesial and distal are terms applicable to tooth surfaces. The mesial surface of the first incisor is next to the median plane; on other teeth it is directed toward the first incisor. The distal surface is opposite the mesial surface.

Figure 1.33 Directions in the oral cavity.

26

Anatomy

Rostral and caudal are the positional and directional anatomical terms applicable to the head in a sagittal plane in nonhuman vertebrates. Rostral refers to a structure closer to, or a direction toward the most forward structure of the head. Caudal refers to a structure closer to, or a direction toward the tail.

Jaws All mammals have two maxillas (or maxillae) and two mandibles. The adjective maxillary is often used in a wider sense, for example, “maxillary fractures” to include other facial bones, in addition to the maxillary bone proper.

Further Reading American Veterinary Dental College. Veterinary dental nomenclature (available at www.avdc.org). Bishop MA, Malhotra M. An investigation of lymphatic vessels in the feline dental pulp. Am J Anat 1990; 187: 247–253. Crossley DA. Tooth enamel thickness in the mature dentition of domestic dogs and cats: preliminary study. J Vet Dent 1995; 12: 111–113. Floyd MR. The modified Triadan system: nomenclature for veterinary dentistry. J Vet Dent 1991; 8(4): 18–19. Gioso MA, Carvalho VGG. Oral anatomy of the dog and cat in veterinary dentistry practice. Vet Clin North Am Small Anim Pract 2005; 35: 763–780. Gracis M. Radiographic study of the maxillary canine tooth of four mesaticephalic cats. J Vet Dent 1999; 16: 115–128. Gracis M. Orodental anatomy and physiology. In: Tutt C, Deeprose J, Crossley D (eds). BSAVA Manual of Canine and Feline Dentistry, 3rd ed. BSAVA, Gloucester, 2007; 1–21. Harvey CE. Anatomy of the oral cavity in the dog and cat. Veterinary Dentistry, WB Saunders, Philadelphia, 1985; 5–22. Harvey CE, Emily PP. Function, formation, and anatomy of oral structures in carnivores, Small Animal Dentistry, Mosby, St. Louis, 1993; 1–18.

27

Hayashi K, Kiba H. Microhardness of enamel and dentine of cat premolar teeth. Nippon Juigaku Zasshi (Japanese Journal of Veterinary Science), 1989; 51: 1033–1035. Hennet P. Dental anatomy and physiology of small carnivores. In: Crossley DA, Penman S (eds). BSAVA Manual of Small Animal Dentistry, 2nd ed. BSAVA, Cheltenham, 1995; 93–104. Hennet PR, Harvey CE. Apical root canal anatomy of canine teeth in cats. Am J Vet Res 1996; 57: 1545–1548. Holland GR. The dentinal tubule and odontoblast process in the cat. J Anat 1975; 120: 169–177. Hudson LC, Hamilton WP. Atlas of Feline Anatomy for Veterinarians. WB Saunders, Philadelphia, 1993. Nanci A. Ten Cate’s Oral Histology, Development, Structure, and Function, 6th ed. Mosby, St. Louis, 2003. Negro VB, Hernandez SZ, Maresca BM, Lorenzo CE. Furcation canals of the maxillary fourth premolar and the mandibular first molar teeth in cats. J Vet Dent 2004; 21: 10–14. Okuda A, Inoue E, Asari M. The membraneous bulge lingual to the mandibular molar tooth of a cat contains a small salivary gland. J Vet Dent 1996; 13: 61–64. Orsini P, Hennet P. Anatomy of the mouth and teeth of the cat. Vet Clin North Am Small Anim Pract 1992; 22: 1265–1277. Rosenzweig LJ. Anatomy of the Cat. Brown Publishers, Dubuque, 1993. Schaller O. Illustrated Veterinary Anatomical Nomenclature, 2nd ed. Enke Verlag, Stuttgart, 2007. Verstraete FJM. Colour Self-Assessment Review of Veterinary Dentistry. Manson, London, 1997. Verstraete FJM, Terpak CH. Anatomical variations in the dentition of the domestic cat. J Vet Dent 1997; 14: 137–140. Vongsavan N, Matthews B. The vascularity of dental pulp in cats. J Dent Res 1992; 71: 1913–1915. Wiggs RB, Loprise HB. Oral anatomy. In: Veterinary Dentistry: Principles and Practice. Lippincott-Raven, Philadelphia 1997, 55–86. Wilson G. Timing of apical closure of the maxillary canine and mandibular first molar teeth of cats. J Vet Dent 1999; 16: 19–21.

Chapter 2

Oral Examination

Treatment planning is based on the results of clinical examination and diagnostic imaging with direction from patient history and dental habits. The best possible treatment outcome is related to an accurate diagnosis. Using a carefully planned examination, the practitioner can recognize both normal and abnormal conditions. A permanent record should be made of relevant medical and dental history and diagnostic data, as well as treatment recommended, performed, and advised for the future.

Patient History Patient history is an important part of the assessment process. Relevant history should include present and past medical information, vaccination status, amount of time spent indoors and outdoors, and information about other animals in the patient’s environment. Discussion of clinical signs related to oral disease in the cat should include difficulty with prehension; difficulty with chewing and/or swallowing food; pawing at the mouth; periodic pain with vocalization when chewing, opening, or closing the mouth; increased salivation with or without hemorrhage; sneezing; nasal discharge; facial swelling; ocular signs; and decreased self-grooming. The intake discussion should include dialogue with the owner concerning their wishes and perception of type and level of service they are expecting to receive. Additionally, the willingness of the client to provide home care, as well as the acceptance of home care procedures by the patient, should be addressed in order to help construct a treatment plan.

Examination of the Conscious Cat Most cats will allow an initial evaluation of their teeth and oral cavity when approached in a slow and gentle manner. The extent of an examination on a nonsedated cat is dependent upon patient cooperation and expertise 28

of the examiner. Some cats are too fractious or painful to inspect without chemical restraint. After a general physical examination, concentrate on the head and face. Signs of facial asymmetry, differences in palpebral sizes, ocular or nasal discharge, discomfort or swelling, pain on palpation, or discoloration should be noted (figs. 2.1 a–g). While looking in the cat’s eyes, palpate along the mandibles and maxillae. Enlarged unilateral or bilateral mandibular lymph nodes should be noted if present during this examination. Holding the head steady in one hand, the rostral portion of the lips is pulled caudally to examine occlusion; missing, extra, or malpositioned teeth; the presence of periodontal disease or oral masses; and fractured, discolored, or resorbed teeth. The mandibular third premolar, often the first tooth affected by tooth resorption, is difficult to observe unless you move the lower lip ventrally (figs. 2.2a–i and 2.3 a, b). During the conscious patient examination, the mouth is opened and closed to evaluate temporomandibular joint movement. To open a cat’s mouth, place one hand on top of the cat’s head with the thumb and forefinger lightly pressing just behind the lip commisures. Pull the lips caudally to reveal the premolars. Tilt the head backward while applying the forefinger of the opposite hand to the mandibular incisor area, pulling the lower jaw ventrally (fig. 2.4). Pain, crepitus, and decreased ability to open or close the mouth are noted on the medical record. Generally, a scissors bite with the maxillary incisors touching and located slightly rostral to the mandibular incisors is considered normal in domestic short hair cats and a majority of the recognized cat breeds. In brachycephalic breeds (Burmese, Himalayan, and Persian), mandibular mesioclusion, where the maxillary incisors are positioned caudal to their mandibular counterparts, is abnormal but considered “normal occlusion” for the breed. Mandibular distoclusion, where the maxillae extend far in front of the mandibles, is not considered normal in any cat breed (figs. 2.5, 2.6, and 2.7).

d

a

e

b

f

c

Figure 2.1 a. Facial swelling secondary to osteomyelitis. b. Mandibular asymmetry secondary to squamous cell carcinoma. c. Horner’s syndrome and mandibular deformity secondary to trauma. d. Decreased palpebral size of the left eye. e. Mild left-sided facial swelling. f–g. Left mandibular swelling and facial staining secondary to complicated mandibular canine tooth fracture.

g 29

a

d

e

b

f c Figure 2.2 a and b. Tooth resorption at the right maxillary fourth premolar. c. Tooth resorption at the right mandibular canine. d–g. Various appearances of tooth resorption at the mandibular third premolar. h. Possible tooth resorption at the left mandibular first molar. i. Tooth resorption confirmed at surgery.

30

g

h

i Figure 2.2 Continued

31

a

b Figure 2.3

a. Discolored left mandibular canine secondary to tooth resorption. b. Discolored left maxillary second incisor secondary to endodontic disease.

Figure 2.5 Figure 2.4 oral cavity.

32

Proper positioning of the right and left hands to examine the

Normal occlusion.

Oral Examination

33

pressure to elicit a pain response; this could indicate the presence of a possible tooth resorption (fig. 2.10). The mandibular canine tooth crowns are normally located in the diastema between the maxillary third incisor and the maxillary canine teeth. There should not be contact between the mandibular canine and maxillary third incisor or maxillary canine when the mouth is closed. Cheek teeth should not occlude (touch each other) as in humans and dogs (fig. 2.11).

Oral Examination under Anesthesia General anesthesia with intubation is essential to properly immobilize the patient for an in depth tooth-bytooth examination, periodontal probing, and intraoral radiography (fig. 2.12). Figure 2.6

Mandibular distoclusion.

Dental Hand Instruments for Examination Periodontal Probe The periodontal probe is used to measure the depth of the gingival sulcus in millimeters to help evaluate the extent of periodontal support. Probes vary in cross-sectional design (rectangular/ flat, oval, or round), with millimeter markings at the calibrated working end. Because the cat’s gingival sulcus is quite narrow, most periodontal probes used in dogs are not appropriate for cats and can cause damage. The author prefers the Michigan O probe with Williams markings at 1, 2, 3, 5, 7, 8, 9, and 10 millimeters (figs. 2.13 a, b).

Figure 2.7

Mandibular mesioclusion.

Probing Depth The dorsal surface of the tongue is examined for symmetry and ulceration. The sublingual area is also visualized for areas of inflammation, swelling, oral masses, and foreign bodies (figs. 2.8 a–e). Healthy gingiva appears light pink. The gingival margin lies next to the tooth 0.5–1 mm coronal to the attached gingiva. Gingival inflammation clinically presents as erythema and causes “rounding” of the originally knife-edged gingival margin. In cats with advanced periodontal disease, attachment loss clinically appears as periodontal pocket formation or gingival recession with root exposure (fig. 2.9). The teeth are grossly inspected for fracture, obvious resorption, and mobility. If the patient will allow, a Q-tip is applied to the gingival/tooth interface with gentle

The clinical or probing depth is the distance between the base of the pocket and the gingival margin. Inserting the periodontal probe into the gingival sulcus and recording millimeter findings is called probing. With gentle pressure, the probe will stop where the gingiva attaches to the tooth. Every professional oral hygiene procedure conducted under general anesthesia should include probing and charting. Cats normally have probing depths less than 1 mm. Greater depths may indicate periodontal disease requiring further evaluation and treatment (figs. 2.14 a, b, c). Two methods of probing are spot and circumferential. Spot probing is the insertion and withdrawal of the probe at a single area per tooth. Because single areas do not represent the entire tooth, an inaccurate assessment may be obtained. Circumferential probing is insertion of

a

c

d

b Figure 2.8 a. Normal-appearing tongue in a cat with extracted mandibular cheek teeth. b. Sublingual tongue mass secondary to squamous cell carcinoma. c. Inflammatory sublingual tongue mass. d. Thickened asymmetric tongue secondary to squamous cell carcinoma.

34

Oral Examination

35

Figure 2.12 General anesthesia necessary for oral assessment, treatment, and prevention.

Figure 2.9 Inflamed gingiva and alveolar mucosa around the maxillary cheek teeth and mucosa of the caudal oral cavity.

a e Figure 2.10 Q-tip gently placed against gingiva to test for bleeding and sensitivity (note: Q-tips can also be used for plaque removal).

b

Figure 2.13 a. University North Carolina probe (Cislak). b. Williams probe (Cislak).

the probe in the sulcus or pocket in at least four places (two buccal and two lingual/palatal) around the tooth, recording millimeter readings. This method compensates for inaccurate readings when subgingival calculus or isolated areas of vertical bone loss are present (figs. 2.15 a, b, c, d).

Clinical Attachment Level Figure 2.11

Normal canine and premolar occlusion.

The clinical attachment level offers greater diagnostic significance compared to the probing depth. Attachment

a

c

b

Figure 2.14 a. Periodontal probe before insertion on the palatal surface of the maxillary fourth premolar. b. 3-mm periodontal pocket. c. 6-mm maxillary canine palatal pocket.

a

c

b

d

Figure 2.15 a–d. Four probed areas around the mandibular third premolar (mesiobuccal, distobuccal, distolingual/distopalatal, mesiolingual/mesiopalatal).

36

Oral Examination

37

a

a

b

c

d

Figure 2.16 a. Number 17 Orban explorer (Cislak). b. ODU explorer (Cislak). c. Shepherd’s hook explorer (Cislak). d. Combination of periodontal probe and explorer (Miltex).

loss or clinical attachment level is determined by measuring the distance from the cementoenamel junction to the pocket base. Alternatively, this measurement is determined by adding the probing depth to the gingival recession measurement (distance between the cementoenamel junction to the gingival margin). Normally, the gingival margin lies less than 1 mm coronal to the cementoenamel junction. With gingival recession, the gingival margin lies apical to the cementoenamel junction. In these cases, the loss of attachment will be greater than the pocket depth.

Dental Explorer A dental explorer has a sharp point (tip) used to examine the tooth for surface irregularities, calculus, resorption, necrotic cementum, and mobility. The explorer can also be used for examination of pulp exposure. The explorer is not used to remove calculus. Explorer examples useful in feline dental pathology assessment include the number 17 Orban explorer, which has a fine 2-mm tip that extends at a right angle from the shank. The O.D.U. (Old Dominion University) number 11/12 is patterned after the Gracey 11/12 curette. The thin tip is especially useful for examining areas of tooth resorption. A Shepherd’s hook explorer, although thicker, can also be used (figs. 2.16 a, b, c, d). Normally, there is a smooth path when the explorer is inserted and withdrawn from the sulcus or pocket.

b Figure 2.17 a. Compressed air applied to suspected tooth resorption of the right maxillary third premolar. b. Explorer used to help confirm presence of tooth resorption of the left maxillary third premolar.

When there is a ledge of subgingival calculus present, the explorer moves over the tooth surface, encounters the ledge, moves laterally over it, and returns to the tooth surface. When fine deposits of subgingival calculus are present, there will be a gritty sensation as the

38

Feline Dentistry

explorer passes over the fine calculus. In cases of tooth resorption and other structural defects, the probe enters the area of dental hard tissue loss (figs. 2.17a, b).

Further Reading Baxter CJK. Oral and dental diagnostics. In: Tutt C, Deeprose J, Crossley D. BSAVA Manual of Canine and Feline Dentistry, 3rd ed. BSAVA, Gloucester, 2007; 22–40.

Harvey EE, Emily PP. Oral examination and diagnostic techniques, Small Animal Dentistry, Mosby, St. Louis, 1993; 19–41. Holmstrom SE, Frost Fitch P, Eisner ER. Dental records, Veterinary Dental Techniques for the Small Animal Practitioner, 3rd ed. Saunders, Philadelphia, 2004; 1–38. Lobprise HB. Treatment planning based on examination results. Clin Tech Small Anim Pract 2000; 15: 211–220.

Chapter 3

Radiology

Dental radiography plays an integral part in most oral assessments. Dental films are indicated for evaluation of apparent pathology, as a way to monitor progression or resolution of treated disease, and as part of the periodic complete dental evaluation. Intraoral radiography offers the capability of viewing pathology below the gingival margin and inside the tooth. Among many other things, it allows us to visibly evaluate tooth vitality; pre-, intra-, and postoperative endodontic treatment; progression of pulpal pathology and/or periodontal disease; and anatomical orientation and documentation of root structure before extraction. Intraoral radiography is also very useful to determine the cause of chronic nasal discharge and to assess the extent of oral neoplasia and severity of maxillofacial trauma. Examination of intraoral films will also allow postoperative evaluation after extraction to confirm all root fragments were removed. It also provides essential information in evaluating tooth resorption and finally provides a baseline record to compare future radiographic studies.

be anesthetized. After approval of the therapy plan and projected fees, the patient is treated. The following is a typical timeline for one patient (other patients are added to the daily schedule depending on availability of anesthesia units and staff):

•

• •

•

• Incorporating Dental Radiography into General Practice Frequently, patients presenting for “routine teeth cleaning and examination” have significant disease. The decision to extract, perform flap surgery, apply local antibiotics, or only clean and polish is made by visual examination, periodontal probing, and dental radiography. Logistically, when the patient is admitted to the hospital for dental evaluation and care, the pet owner cannot receive an accurate treatment plan until a thorough tooth-by-tooth assessment is conducted. The client is encouraged to return to the office or call at a specific time, or is paged usually two or three hours later to discuss the treatment plan based on clinical examination and radiographic findings while the patient continues to

• •

9:00 a.m.: The patient is examined or left for an examination. The owner is advised to call the office or come back at noon for discussion of dental examination and radiographic findings, while the animal is still anesthetized. 9:30–10:30 a.m.: Preoperative laboratory and electrocardiographic evaluation are performed. An intravenous catheter is placed. 10:30–11:45 a.m.: The patient is anesthetized, teeth are cleaned, the mouth is probed and charted, and oral survey radiographs are exposed by the staff. A treatment plan is formulated by the veterinarian and fees are calculated. 12:00 p.m.: The client calls. The veterinarian discusses examination findings, treatment plan, and fees while the technician is completing the dental cleaning procedure. 12:10 p.m.: When the treatment plan is approved, therapy begins. 2:00 p.m.: Therapy is completed (time depends on procedure). 5:00–6:00 p.m.: The patient is discharged, with a discharge order and picture report discussion with the owner.

Radiograph Unit Although the veterinarian may choose to use a conventional whole-body radiograph unit, acquiring high-quality dental images requires a dedicated dental radiograph unit for a multitude of reasons:

•

Shorter film focal length and automatic collimation result in less scattered radiation and radiation exposure to the patient and staff. 39

40

•

•

Feline Dentistry

Ideal tube positioning is greatly facilitated by tube support, arms of various lengths that allow vertical, horizontal, and rotational movement, resulting in less patient repositioning. Radiographs can be obtained on the dental operatory table rather than moving the patient to a dedicated radiography area (figs. 3.1 and 3.2 a, b, c ).

Most dental units are economically priced between US$3,000 and US$5,000, requiring a small cash outlay, and a long arm can reach two closely located operatory areas. The position indicating device (PID) is an extension placed on the tube head at the collimator attachment. To minimize the amount of radiation exposure, the PID is lead lined. (Note: older units may not be lead lined.) The shape of the PID may be circular or rectangular. Dental lead-lined cones are available in a variety of lengths from 4 to 16 inches. The end of a 4-inch cone may be 8 inches from the radiograph generator. An 8-inch extension (using a 4-inch cone) is referred to as shortcone technique; longer extensions result in a long-cone technique. Exposure adjustments to accommodate different cone lengths employ the inverse square rule. For

example, a 4-inch cone requires one-fourth of the exposure of an 8-inch cone. Generally, short-cone technique, which produces less magnification, is preferable because it uses a quarter of the exposure and is easier to position. The long-cone technique, however, produces films with less divergence and scatter. The arm connects the radiograph tube and the control panel. The control panel contains the timer, kilovoltage (kV), and/or milliamperage (mA) regulators. Most machines have a fixed kV (50–120) and mA (7–15). The only variable parameter is duration of the exposure in fractions of seconds or pulses (figs. 3.3 a, b). The exposure timer regulates the time an exposure lasts. The timer is engaged only while the switch is depressed and automatically stops at the end of the preset exposure. The timer resets after each exposure. Most dental units use 110V, 60Hz AC electricity. A separate dedicated electrical circuit is recommended. The kilovoltage peak (kVp) determines the penetrating power or quality of radiation produced. Kilovoltage affects the contrast (shades of gray). The higher the kVp setting, the higher is the photon energy that strikes an area. To penetrate larger teeth, a higher kilovoltage is required to produce a diagnostic film. When using ultraspeed D film, the kVp setting varies from 40 to 70, depending on the tooth and animal size or on the generator used.

Digital Imaging

Figure 3.1

Ceiling-mounted radiographic generator and monitor.

Digital imaging is a major technical advancement in companion animal dental radiography. Instead of film, an electronic sensor pad is placed against the teeth; the pad senses radiation and transfers the pattern as an image to a computer screen where it can be enhanced, enlarged, e-mailed, printed, or archived. A dental radiographic unit is still needed to expose the sensor. Approximately 1/10 to 1/2 of the nondigital exposure is commonly needed to obtain a diagnostic image; however, some systems need the same amount of radiation as F-speed film. Because of low time exposure settings, older dental radiographic machines may not have fast enough timers to produce digital images. The direct-to-digital sensors used in the patient’s mouth are available in two sizes, similar to film numbers 1 and 2. Phosphor transfer sensors are available in four sizes, similar to film numbers 0, 1, 2, and 4. Parallel and bisecting angle techniques are used to position the sensor and PID properly. The operator selects the tooth or quadrant to be exposed from computer software. In direct systems, images will appear on the screen within a matter of seconds (figs. 3.4 a, b).

a

b

c

Figure 3.2 a. Dental operatory with cabinet mounted radiograph unit. b. Portable handheld radiograph generator (Nomad). c. Wall-mounted radiograph unit (Progeny Vet Vision by Midmark).

41

a

a

b Figure 3.4 a. Wired direct radiography (DR) sensor (EVA AFP Imaging). b. Computed radiography (CR) film plate (Scan X).

b Figure 3.3 a. Control panel Image-Vet 70 plus (AFP Imaging). b. Control panel (Nomad).

42

Radiology

Image quality is equivalent to traditional dental films. The software allows a variety of options for enhancing and manipulating the image for greater diagnostic value. The tools used most often include enlargement, autocontrast, grayscale resolution, spotlight features, inversion of colors, and measurement rulers (figs. 3.5 a–f).

Radiation Safety ALARA Radiation exposure should be “as low as reasonably achievable” (ALARA). This concept endorses exposing the patient (and operator) to the lowest possible amount of radiation necessary to produce a diagnostically acceptable radiograph. Staff of the veterinary facility must be protected against excessive radiation exposure. Radiograph aprons, gloves, and thyroid shields should be worn when exposing films. Personal radiation monitoring devices are required in most states. Veterinarian responsibilities include (1) prescribing only radiographs that are clinically necessary, (2) installing and maintaining the radiographic equipment in a safe working condition, and (3) adequate training, supervision of, and monitoring of personnel who expose radiographs. Two types of radiation apply to operator safety. Primary radiation comes from direct exposure to the radiograph beam. The veterinarian or staff should never hold film or digital sensors in the patient’s mouth with bare or even gloved fingers. To avoid finger exposure, film or sensors can be positioned in the mouth using the endotracheal tube, clay encased in a plastic bag, gauze, or crumpled newspapers, decreasing operator exposure. Secondary (scatter) radiation reflects from areas that have been irradiated by the primary beam. Protective devices must be worn for shielding.

Film Intraoral, nonscreen film can be used in small animal dental radiography. It is inexpensive and flexible and provides diagnostic detail. The author prefers digital imaging using sensors to replace film. Individual dental films are packaged in a light-safe packet made of either Poly-Soft plastic or paper material. The back of the packet has a tab used to open the packet and remove the film for processing. The tabbed side is placed away from the radiation beam. Inside the packet, film is positioned between two sheets of black paper. Lead foil, which protects film from secondary backscatter radiation, is located next to the tab opening (fig. 3.6). Intraoral dental film is packaged with one or two films per packet. The practitioner may use the second film to give to the client or referring veterinarian, or to archive interesting cases.

Film Speed The efficiency with which a film responds to radiograph exposure is known as film sensitivity or speed:

• • •

D speed (Ultraspeed, Kodak) provides high contrast and fine detail. Ultraspeed is the most popular film used for veterinary dentistry. E speed (Ektaspeed, Kodak) requires 25% less exposure time than D speed film, with minimal loss of contrast. F speed (InSight, Kodak) requires 60% less exposure time than D speed film, and 20% less than E speed film.

Kodak film packet backs are color coded to indicate film speed and number of films in the packet.

Film Sizes

•

Personnel Monitoring A film badge service is used to provide radiation monitoring for all members of the office staff functioning near radiation exposure. The dosimeter badge should be worn at all times in the veterinary office. It measures the amount and type of radiation an individual is exposed to in the working environment. The badge should not be worn outside the office. The periodic radiation monitoring report should be evaluated and saved indefinitely.

43

•

•

Small periapical (size 0, Kodak Ultraspeed DF-54) measures ⅞ × 1⅝ inches. Size 0 is used mostly in cats due to the small-sized film. It is appropriate for the parallel technique of the mandibular cheek teeth (P3-M1) (fig. 3.7a). Large periapical (size 2, Kodak Ultraspeed DF-58) measures 1¼ × 1⅝ inches. It is appropriate for the near parallel technique of the maxillary cheek teeth (P2–M1) and bisecting angle of the mandibular incisors and canine teeth (fig. 3.7b). Occlusal (size 4, Kodak Ultraspeed DF-50) film measures 2¼ × 3 inches. Occlusal film is used in extraoral technique and nasal studies. It is appropriate for the maxillary occlusal view (fig. 3.7c).

a

b

c

d Figure 3.5 Rostral mandibles: a. Underexposed film. b. Exposure correction. c. Inverse. d. Enlarged part of image. e. Intraoral radiograph of bilateral tooth resorption at the mandibular canines. f. Software color enhancement (Schick).

44

e

f Figure 3.5 Continued

45

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Feline Dentistry

Figure 3.6

Opened film packet (film light green color).

Digital Format Sensor (Plate) Sizes Direct-to-digital sensors are currently marketed in size 1 and 2 formats (figs. 3.8 a, b, c, d). Phosphor transfer digital plates are available in sizes 1, 2, and 4 (fig. 3.8e).

Film Dot Most dental films are embossed with a raised dot (or dimple) in one of the corners. The dot is used to identify right from left. The side of the film containing the raised (convex) side of the dot indicates the side to be positioned toward the radiation beam (figs. 3.9 a–f).

There are many methods for using the film dot for tooth identification. One method places the raised dot against the cutting edge of the teeth and toward the tube head. Using this system to determine whether a processed film is from the right or left side, the progression of the teeth from molars to incisors is identified, as well as the location of the raised film dot. With this method, the “apple” and “par” rule can be applied. Apple stands for anterior to posterior (rostral to caudal) = left side. Par stands for posterior to anterior (caudal to rostral) = right side.

a

b

c

Figure 3.7 a. Size 0 film. b. Size 2 film. c. Size 4 film.

47

a

d

b

c e Figure 3.8 a. Sizes 1 and 2 digital sensors (EVA, AFP Imaging). b. Schick Technologies 0, 1, and 2 digital sensor sizes. c. Schick Technologies sensor attached to control box. d. Progeny Vet Vision Digital Sensors by Midmark. e. Sizes 2 and 4 digital phosphor plates (Scan X).

48

a

b

e

c f

d

Figure 3.9 a. Scan X digital phosphor plate film position mark “a” circled. b. Film marker “a” indicating left maxilla. c. Digital sensor position marker (arrow) indicating left maxilla. d. Film packet embossed dot (arrows). e. Right mandible film placement with marked film dot. f. Left rostral mandible film placement with marked film dot.

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Feline Dentistry

A lesser used alternative system positions the dot on the right side of the radiographed object. When reading the radiograph, if the dot is in the “air,” it is the right side. If it is in the “bone,” it is the left side. Most digital sensors and phosphor plates are marketed with embedded position indicators.

Tube/Film/Patient Placement

(see Table 3.1)

A radiographic dental survey consists of a minimum of six views:

• • • • • •

Rostral maxilla including the canines Rostral mandible including the canines Right maxillary cheek teeth Left maxillary cheek teeth Right mandibular cheek teeth Left mandibular cheek teeth

the film, creating a nondistorted image. Only the mandibular cheek teeth allow the film to be placed lingually (parallel) in the flexible intermandibular soft tissue parallel to the roots. Parallel technique is not usually feasible for most studies. Instead, the bisecting angle technique is used. Imaginary lines are drawn along the long axis of the tooth/teeth and the plane of the film. The point where these two lines meet creates an angle. Instead of aiming the central beam perpendicular to the film, as in the parallel technique, the central beam is aimed perpendicular to the imaginary line that bisects the angle formed by the plane of the film and the long axis of the tooth.

Positioning for the Maxilla

The film should be placed inside the mouth, as parallel as possible to the long axis of the tooth roots to be radiographed. The nontabbed side faces the tube head. The film can be held in position by the endotracheal tube, wadded-up newspaper, gauze, hair curler devices, lead radiograph gloves (without fingers inside), sponges, clay encased in plastic bags, or by commercial holding devices. Operators must not use their fingers to hold film during exposure. Vertical angulation refers to the up-and-down movement of the PID. Vertical angulation determines how accurately the length of the object being radiographed is reproduced. Horizontal angulation refers to rostral-caudal movements of the tube head. Proper horizontal angulation produces normal interproximal anatomic representation of the teeth without overlapping. Parallel technique places the film parallel to the tooth, and the radiograph beam is positioned perpendicular to

Incisors: Place the film packet or sensor toward the tube head against the incisors and palate. Position the PID perpendicular to an angle that bisects the film and teeth planes (fig. 3.10 a). If present and anatomically normal, both canines should touch the film (figs. 3.10 b, c, d). Canine: Place the film packet facing the tube, between the tongue and maxilla and beneath the canine tooth root. Center the PID over the mesial root of the second maxillary premolar, dorsally or laterally depending on the view needed. Determine the angle between the axis of canine tooth root plane of the canine tooth root and the plane of the film. Position the cone perpendicular to the bisected angle. The lateral oblique view is recommended for close inspection of the periapical region of the canine tooth (figs. 3.11. a, b). Premolars and first molar intraoral technique: Place the film packet as close as possible to the inner surface of the cheek teeth. For the maxillary view of the cheek teeth, the patient is positioned in sternal recumbency with a support placed under the chin, at a height where

Table 3.1. Intraoral Radiographic Overview. View

Position

Technique

Film Size

Exposure Time at 60 kV and 7 mA (in seconds)

Maxillary incisors and canines

Intraoral occlusal

Bisecting angle

2

0.16

Maxillary premolars and molars

Intraoral and/or extraoral

Near parallel

2

0.20

Mandibular incisors and canines

Intraoral occlusal

Bisecting angle

2

0.12

Mandibular premolars and molars

Intraoral

Parallel

0 or 2

0.12

a

b

d

c

Figure 3.10 a. Bisecting angle tooth, sensor, and beam position illustration. b. Patient, sensor, and tube head positions for intraoral films of the maxillary incisors. c. Maxillary incisor teeth touching the digital sensor. d. Rostral maxilla image.

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a

b Figure 3.11 a. Lateral oblique tube head and sensor position. b. Lateral oblique maxillary canine image.

the muzzle is parallel to the tabletop. A size 2 film or sensor is placed into the mouth (film white side toward the palate). Aim the PID at the roots of the premolars at approximately 45 degrees. The maxillary fourth premolar has three roots (mesiobuccal, mesiopalatal, and distal). To avoid overlap of the mesiobuccal and mesiopalatal roots, position the PID caudal oblique (figs. 3.12 a, b).

Due to superimposition of the zygomatic arch over the maxillary cheek teeth, satisfactory views may not be obtained using the standard bisecting angle technique (fig. 3.12c). To avoid the zygomatic arch, use a rostral oblique extaoral bisecting angle projection, aimed at the premolar roots with the PID positioned just ventral to the arch aimed at the palatal surfaces of the teeth. The film is

a

b

c

d

e

Figure 3.12 a. Patient, tube head, and sensor position to expose maxillary cheek teeth. b and c. Maxillary cheek teeth image—note superimposition of the zygomatic arch over the fourth premolar. d and e. Extraoral radiographic patient, tube head, and film and sensor positions. f. Extraoral image without zygoma superimposition.

f

53

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placed extraorally on the table. The cusp tips of the premolars should be near the lower edge of the film, so most of the film is under the maxilla and zygomatic arch (figs. 3.12 d, e, f). The embossed dot is along the lower edge of the film. When extraoral technique is used, right will appear to be left when viewing the film. The raised dot on the film should now be mounted so the indented dimple (concave side) is toward the viewer. This will help to avoid misinterpreting right from left when viewing the mounted intraoral radiograph.

Positioning for the Mandible Place the patient in dorsal or lateral recumbency with support under the neck so the muzzle is parallel to the tabletop.

a

b Figure 3.13 Rostral mandible: a. Tube head and sensor position. b. Image.

Incisors: Position the film packet toward the tube head against the incisors on top of the tongue. Position the PID perpendicular to the bisecting angle (figs. 3.13 a, b). Canine: Place the patient in ventral recumbency. Position the film on top of the tongue. To obtain a lateral view, position the PID approximately 45 degrees toward the canine (fig. 3.14). Premolars and first molar: Place the cat in lateral recumbency, with the film or sensor at the floor of the mouth lingual to the premolars. Place gauze or a hemostat to help depress the film into the floor of the mouth. Aim the PID perpendicular to the tooth roots and film (parallel technique). Occasionally, a slightly caudal oblique position of the PID enables viewing the distal root of the mandibular molar (figs. 3.15 and 3.16 a, b, c, d).

Figure 3.14

Lateral view of the mandibular canine.

Figure 3.15

Parallel technique used when imaging the mandibular premolars.

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a

b

d

c Figure 3.16 a and b. Left mandibular premolars and first molar. a. Patient, tube head, and sensor position. b. Left mandibular premolars and first molar image. c and d. Right mandibular premolars and first molar. c. Patient, tube head, and sensor position. d. Right mandibular premolars and first molar image.

Temporomandibular Joint The temporomandibular joint (TMJ), also called the craniomandibular joint, is a transversely elongated, synovial joint formed by the condylar process of the mandible and the mandibular fossa of the temporal bone. The reticular process is a caudoventral extension of the man-

dibular fossa that partially envelops and prevents caudal luxation of the mandibular condyle. At the rostral margin of the mandibular fossa there is a small, unnamed protuberance. The joint may be affected by congenital defects (most commonly dysplasia), trauma (luxation, fracture), infection (septic arthritis, non-infected degenerative joint

Radiology

57

a

b Figure 3.17

a. Intraoral temporomandibular joint (TMJ) positioning. b. Exposed intraorally obtained temporomandibular joint image.

disease), and neoplasia. Imaging of the TMJ can be difficult. Intraoral or extraoral techniques can be used to view the joint. When using an intraoral technique, a number 2 or number 4 film can be placed in the oropharynx wedged under the endotracheal tube in the area of the TMJ. The PID is placed against the ear canal (figs. 3.17 a, b).

Alternately, an extraoral technique can be used. Standard radiograph views include closed dorsoventral/ ventrodorsal, lateral, lateral oblique, and open-mouth. The dorsoventral (DV) position usually gives the most information concerning the TMJ. The radiograph beam should be centered between the two TMJs with care to assure symmetric positioning of the head. This is

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a

a

b Figure 3.18 a. Dorsoventral positions for exposure of the TMJs. b. Exposed extraoral image with TMJs circled.

b Figure 3.19

often difficult in patients that have suffered head trauma. In those cases, ventrodorsal (VD) views may be easier to obtain. The normal TMJ space is a thin, sharply marginated, radiolucent band of uniform width (figs. 3.18 a, b). Lateral positioning is accomplished with the nose raised 15 to 20 degrees. However, true lateral views of the TMJs are not usually diagnostic due to superimposition, unless the radiograph beam is centered over the third cervical vertebra and the film focal distance is 100 cm. Due to parallax, both TMJs will be visible on one

a. Straight lateral. b. Superimposition of the TMJs.

radiograph with the TMJ closer to the film cassette being more caudal (figs. 3.19 a, b). Lateral oblique is another option that allows the TMJs to be viewed without superimposition. The head is rotated 20 degrees along its median axis, and the TMJ closer to the film cassette is projected clear of the skull ventrally (figs. 3.20 a, b).

Radiology

59

a

b Figure 3.20 a. Extaroral lateral oblique positioning to evaluate left TMJ in a cat skull. b. Lateral oblique image, the left TMJ located ventrally to the opposite TMJ on the radiographic image.

Even with good-quality dorsoventral and lateral oblique views, an accurate diagnosis of TMJ pathology may not be possible based on analog or digital images. In those cases, thin-sliced computed tomography offers superior imaging of the TMJ.

SLOB Rule The “SLOB rule” (same lingual, opposite buccal), also called the “buccal object rule,” is a tube-shift technique that helps identify the relative bucco-lingual location of

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objects in the oral cavity. When two roots of a triplerooted tooth (e.g., the maxillary fourth premolar) are superimposed on the radiograph, it is sometimes difficult to distinguish the individual roots. Defining which root is which is important when pathology associated with advanced periodontal disease or foreign bodies is discovered. To visualize the roots, two radiographs are taken at oblique angles, fixing the vertical position and moving the tube horizontally. Horizontal tube shift will separate the superimposed roots on the film. The root that “moves” in an opposite direction to the horizontal shift of the tube, is labial or buccal. For example, when the tube head is moved rostrally, the mesiopalatal root of the right or left maxillary fourth premolar will be the most rostral root on the radiograph, and the mesiobuccal root will be caudal to the mesiopalatal root. Generally, when a root “moves” in the same direction as the tube head, it is located more lingual or palatal compared to the other root(s). Elimination of movement is essential to image sharpness. During exposure, movement of the film packet, patient’s head, or PID must be avoided.

Film Processing Emulsion film may be developed either manually or automatically. Digital images are processed through the computer. With manual processing, the operator moves the film from the developer, water, and fixer solutions in the practice darkroom or in a chairside darkroom. With the chairside darkroom, a portable light-safe box containing developer, distilled water, and fixer in small containers is placed in the dental operatory. The chairside darkroom is covered with a Plexiglas safety filter, which enables operators to see their hands while handling the film(s). The filter is either amber (when D speed film is exposed) or red (for E or F speed films). Processing time from opening the film packet to initial examination of a rinsed film takes approximately 2 minutes (figs. 3.21 a, b). Developer and fixer jars in the chairside darkroom should be covered when not in use. Depending on the chemical manufacturer, number of films processed, and environmental conditions, the fixer and developer remain usable for 2 days to 2 weeks. To maximize the life of the developer, stock solutions can be stored in a refrigerator. The developer and fixer should be brought to room temperature before use. Manual processing includes the following steps: 1.

After exposure, carry the film into the practice darkroom or chairside darkroom for processing. Slide the

a

b Figure 3.21 a. Chair-side developer unit. b. Individual cups for developer, water, fixer, and water inside the chair-side developer.

film packet tab down to present the film, cardboard, and lead blocker. The film will feel firm to the touch compared to the other film packet contents. 2. Attach a film hanger to the film edge. Touch only the sides of the film with your fingers. Apply a gentle tug to make certain the film is firmly attached to the hanger (fig. 3.22a). 3. Place the film into developer solution for the specified time recommended by the manufacturer (Kodak

Radiology

61

Figure 3.23 Automatic film processor.

4.

a

b Figure 3.22 a. Attached film hanger. b. Film and hanger placed into developer solution.

After removal from the developer, rinse the film in fresh distilled water (wash) for 10 to 15 seconds. Rinsing removes the alkaline developer from the film surface, preventing mixture with the acid fixer. 5. Place the film into fixing solution for at least 2 minutes. Fixer removes the unexposed or underdeveloped silver halide crystals and rehardens the emulsion. 6. Rinse the film for 30 seconds in distilled water. 7. After viewing, place the film back into fixer for 5 minutes, followed by a distilled water rinse for 10 minutes. 8. When rinsing is complete, attach the radiograph to a clip on the drying rack. When using an automatic standard film processor, the dental film can be attached to a larger film with silver photographic tape. This procedure is discouraged because small dental films might become lost in the processor, and/or the tape might harm the processor ’s rollers. An automatic dental film processor with a light-safe feeder can be located in the chairside darkroom or a separate darkroom. Exposed dental film(s) are inserted at one end of the automatic dental processor and exit fully developed, fixed, and dried in 5 to 7 minutes (or in 2 minutes, rapid cycle, for endodontic intraoperative films not fully fixed) (fig. 3.23).

Automatic Processing Rapid Access Chemistry: 15 seconds at 68 degrees). Note: an alternative method starts manual film processing with water immersion to soften the emulsion before placement in the developer (fig. 3.22b).

1. 2.

Remove all wrappers around the film in the darkroom. Insert the film into the film processor.

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Quality Control A good radiograph is useless unless it can be read accurately, and a poor radiograph cannot be read accurately. Daily, a quality assurance film should be exposed to verify that all parts of the dental radiography system are working properly. Use of an aluminum step wedge helps accomplish this goal. The step wedge is composed of graduated pieces of aluminum placed to produce a step effect (figs. 3.24 a, b). To use a step wedge to establish a control radiograph:

1. Lay a dental film tab-side down on a flat surface. 2. Place a step wedge over the film. 3. Use previously described techniques to expose the film. 4. Process the film using new chemicals in a lightsecured area. The processed image should show ten shades of varying densities, from light gray to black. If all ten steps are not apparent, adjust the exposure up or down until all can be distinctly seen. If the lightest steps (from the thickest part of the wedge) are indistinct, the exposure is increased. If the darkest steps (from the thinnest part of the wedge) are indistinct, the exposure is decreased.

a c

b d Figure 3.24 a. Aluminum step wedge placed on film. b. Tube head position to expose quality control film. c. Reference film with clearly identified density shades. d. Reference film processed in exhausted chemicals with blurred density shades.

Radiology

When the correct exposure is determined, this becomes the control film. Thirty reference films are exposed but not processed. Reference films should be stored in a refrigerator. (figs. 3.24 c, d) The control film is placed on the view box. Every day, one of the pre-exposed reference films is developed to confirm that the density (overall darkness of the image) and contrast (number of visible steps of the wedge) remain constant when compared to the baseline film. If they are not identical, the correct processing time and temperature are verified. If more than two steps are lighter than the control film, and other variables have not changed, the developing and fixing solutions should either be replenished or changed. Film quality encompasses many variables, including

• •

• •

Detail: the delineation of minute structure, controlled by kVp and the developing process. Definition: the distinctness and demarcation of the detail that make up the radiographic images, controlled by distance, focal spot size, type of film, and motion. Adequate definition is present when the apical lamina dura, periodontal ligament space, and individual bone trabeculae can be clearly demarcated around a healthy tooth. Density: the degree of whiteness created on the film, controlled predominantly by mAs; settings of 10– 12.5 mAs typically provide adequate detail. Contrast: the relative difference between densities, controlled by kVp (normally between 40 and 75) and processing variables (temperature, humidity, development time, light leaks, and inherent characteristics of film); high-contrast films appear black and white, while low-contrast films demonstrate many shades of gray.

63

Film Fogging Film fogging appears as a gray or dark film and can have several causes:

• • • •

• •

Insufficient fixation time (most common reason). To correct this fault, immerse the film in the fixer for an additional 5 minutes. Exhausted processing chemicals Expired film Light leaks from the film packet or processing area. To evaluate whether the processing area was at fault, place a coin on top of an open unexposed film packet in the dark room for 10 minutes, then process the film; if an outline of the coin shows, there is a light leak in the darkroom. Overdeveloped film Film processed in fixer contaminated with developer solution

No Image

• •

Film immersed in fixer before developer Film unexposed (either due to poor PID positioning, packet placement, or failure to engage the timer)

Light Image

• • • • •

Decreased exposure time Decreased kilovoltage Contaminated or exhausted developing solution Decreased developing time Inappropriate film placement in the mouth

Dark Image

Troubleshooting Foreshortened Image The exposed dental image should be approximately the same size as the patient’s tooth. Foreshortened images, caused by excessive vertical angulation, appear shorter than the patient’s anatomy. To correct a foreshortened image, the vertical angulation is reduced.

• • • • •

Overexposed film Excessive kilovoltage Increased exposure time Overdeveloped film Warm developing solution (ideal temperature is 68 °F)

If the film is black, then it may have been exposed to light before processing.

Partially Visible Image Elongated Image Elongated images, caused by too little vertical angulation, appear longer than the actual tooth. To correct an elongated image, vertical angulation is increased.

• • •

The film was partially immersed in the developer. While in the developer, the film became attached to other films or the side of the container. The film or tube head was incorrectly positioned, creating cone cutoff.

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Feline Dentistry

For labial mounting:

Blurred or Double Images Blurred and double images are caused by movement of the patient, film, or radiograph machine head, or by exposing a film twice. If the movement continued throughout the exposure, the image will be blurred. Movement where the film was in one position for part of the exposure and then maintained in a second position for the remainder of the exposure will display a double image. Tongue movement in lightly sedated patients may move the film during exposure.

•

• • •

Other Complications

• •

• • •

Fingerprints occur from poor handling while processing (wet hands, fingertips). The film should be handled only by the edges. Frosty films occur from insufficient removal of fixer when rinsing manually processed films. The remaining residue dries on the film, leaving a frosty finish. Rinsing a processed film with fresh distilled water for sufficient time easily prevents frosty films. Streaked films might occur when the film is insufficiently developed, fixed, or rinsed. Contaminated processing solutions might be at fault. Crescent-shaped lines occur when the film packet is sharply bent. Low-density tire tracks or geometric patterns on the film occur as the result of directing the radiograph through the lead foil side of the film packet.

• •

All radiographs of the dental survey are placed on a flat view box with the convex side of the dot toward the viewer (any films made using extraoral technique are placed with the convex dot away from the viewer). The radiographs are arranged anatomically; maxillary above, mandibular below. The patient’s right side should be placed on the left side of the box. The maxillary radiographs are positioned with the crowns of the teeth facing the bottom of the view box. The mandibular radiographs are rotated until the coronal portions of the teeth are directed toward the top of the view box. The films are placed into the mount as positioned on the view box. The rostral maxillary and mandibular views are mounted in the upper and lower center mount openings.

Lingual mounting (sitting on the tongue), where films are placed in the mount with raised dots facing away from the viewer, is less commonly utilized. In this method, radiographs are viewed as if the viewer is inside the patient’s mouth looking out; the patient’s left side is on the viewer ’s left side.

Radiograph Interpretation Radiographic Landmarks

Film Storage and Mounting Film mounts are used to organize and store radiographs. Mounts are available in a variety of styles, materials, and sizes of windows (openings) to accommodate the patient’s radiographic survey. All the radiographs in a single series should be in the same mount and labeled with the patient’s name and date of the study. Digitally displaying full-mouth survey films is easy when using templates (fig. 3.25). There are two common methods used to mount films. Both rely on the knowledge of the normal radiographic anatomical landmarks for each region of the mouth, tooth morphology (shape and form), and identification of the embossed corner dot. Labial mounting (nose to nose), wherein the films are placed in the mount with the raised dots facing the viewer, is most commonly used. The radiographs are examined as if the viewer is looking directly at the patient nose to nose; the patient’s left side is on the viewer ’s right side, and the patient’s right side is on the viewer ’s left side.

It is important to be able to look at a film and anatomically identify the area exposed:

•

•

•

•

The maxillary incisor area contains a radiopaque (white) area caudal to the incisors, with two radiolucent (black) ovals representing the palatine fissures (fig. 3.26). The maxillary premolar and molar area contains a radiopaque fine line apical to the roots, representing the nasal surface of the alveolar process—a white line caused by tangential beam to the 45-degree angle of the ventrolateral surface of the maxillary recess (caudally) and nasal cavity (rostrally). The maxillary recess does not extend over the second and third premolars (fig. 3.27). The mandibular incisor area has a linear radiolucent area representing the mandibular symphysis, separating the right and left mandibular bodies (fig. 3.28). The mandibular premolar and molar area has radiolucent areas above and below the body of the mandible (fig. 3.29).

INC CAN-PM-M

CAN M-PM

Figure 3.25

Digitally displayed oral film survey.

CAN-PM-M

INC

CAN PM-M

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Figure 3.28

Mandibular incisors and canines.

Figure 3.26 Maxillary incisors and canines.

Figure 3.27 Maxillary premolars and first molar. Figure 3.29 Mandibular premolars and first molar (affected by Stage 4 periodontal disease).

Mental foramina are normal radiolucent anatomical structures that may be confused with pathology. Cats have three mental foramina:

•

The rostral mental foramen is located ventral to the incisor apices near the symphysis.

•

The middle mental foramen is located ventral to the mesial root of the second premolar in the dog and distal to the root of the canine tooth in the cat. The middle mental foramen may radiographically appear as a periapical lucency suggesting endodon-

Radiology

Figure 3.30

Middle and caudal mental foramina.

Figure 3.31

•

67

tic disease. If in doubt, the tooth can be radiographed in an oblique angle, which will show that the foramen is not connected to the tooth’s apex. The caudal mental foramen is located ventral to the mesial root of the mandibular third premolar (fig. 3.30).

The mandibular canal appears as a lucent tubular structure parallel to the ventral border of the mandible. The mandibular canal may be superimposed on the apices of the mandibular cheek teeth, giving the appearance of periapical disease (fig. 3.31). The alveolar margin (also called alveolar crest) is the cortical border of the alveolar process positioned approximately 0.5–1 mm apical to the cementoenamel junction in the cat. The shape of the alveolar margin varies from pointed to flat. The rostral alveolar margins appear sharply pointed. Normal cheek teeth alveolar margins appear parallel or flat between adjacent cementoenamel junctions (fig. 3.32). The lamina dura is a radiographically visible, thin radiopaque line that represents a layer of compact bone lining the alveolus. The lamina dura is not a structure in its own right but represents the radiographic image of the dense cortical bone that is continuous with the alveolar margin. It appears dense and uniform in the younger

Mandibular canal.

animal, becoming ill-defined in the aged patient or in various disease states. The lamina dura is separated from the root by a radiolucent line, which represents the periodontal ligament space (fig. 3.33). The lamina dura of each tooth should be inspected to see whether it is continuous or breached (indicating pathology). A complete lamina dura generally indicates good periodontal health. In cases of early and established periodontal disease, the coronal lamina dura appears radiographically indistinct, irregular, and fuzzy. Resorption of the alveolar bone with advanced stages of periodontal disease leads to widening of the periodontal ligament space and loss of lamina dura. When viewing the lamina dura and the periodontal ligament space, only the interproximal portions are visible. The buccal and lingual walls of the alveolus do not project a lamina dura since they are perpendicular to the radiograph beam. With disease, the periodontal ligament space may appear with varying thickness, indicating that involvement is not consistent around the entire root. The periodontal ligament space normally appears radiographically as a uniform radiolucent area between the lamina dura and tooth root. It is normally wider in

68

Feline Dentistry

Figure 3.33

•

Figure 3.32 Alveolar margin.

•

• younger animals and narrows with advancing age. The periodontal ligament space also appears wider due to tooth mobility in the presence of periodontal disease.

•

Lamina dura.

Unilocular corticated. The radiolucent space exhibits one space. If they have borders, they are corticated, usually a border of radiopaque rim of bone. Examples: periapical cyst, granuloma, and dentigerous bone cyst. Unilocular noncorticated. There is no presence of the thin radiopaque rim of bone at the periphery. Instead, it appears fuzzy and ill-defined. Examples: osteomyelitis and neoplasia. Focal opacities. Well-defined localized lesions. Examples: condensing osteitis and periapical cemental dysplasia. Irregular or ill-defined opacity. Pattern often observed in malignant conditions as well as osteomyelitis.

Radiographic Terminology

•

•

Radiolucent. That portion of the processed radiograph that is dark or black. Radiolucent structures include resorption, soft tissues, dental pulp, and the periodontal ligament space. Radiopaque. That portion of the processed radiograph that is light or white. Radiopaque structures include enamel, dentin, bone, and mineralization of soft tissues.

Periodontal Disease Periodontal disease can be classified in stages 1 to 4 based on severity of radiographic and clinical signs. In the normal cat without periodontal disease, the alveolar margin resides 0.5–1 mm apical to the cementoenamel junction. The radiograph is used indirectly to determine degree of bone loss. The bone level in periodontal disease often

Radiology

decreases as inflammation extends and bone is resorbed. A significant amount of compact (or cortical) bone is lost before bone loss can be radiographically visualized. Distribution of bone loss is classified as either localized or generalized, depending on the number of areas affected. Localized bone loss occurs in isolated areas. Generalized bone loss involves the majority of the marginal bone. Specific areas of bone loss may be classified as horizontal (perpendicular to the tooth) or vertical (angular along the side of the root). Stage 1, gingivitis, occurs when the gingiva appears inflamed. There is no periodontal support loss or radiographic change. Stage 2, early periodontitis, occurs when attachment loss is less than 25%, as measured from the cementoe-

a

69

namel junction to the apex. Clinically, early periodontitis is typified by pocket formation or gingival recession. Radiographically, stage 2 disease appears as blunting (rounding) of the alveolar margin in addition to bone loss. There may also appear to be a loss of continuity of the lamina dura at the level of the alveolar margin (fig. 3.34a). Stage 3, moderate periodontitis, is diagnosed when 25%–50% of attachment loss occurs. The direction of bone loss may be horizontal or vertical (angular) (figs. 3.34 b, c). Horizontal bone loss radiographically appears as decreased alveolar bone along adjacent teeth. Normally, the alveolar margin bone is located 1 mm apical to the cementoenamel junction. With horizontal bone loss,

b

Figure 3.34 a. Early periodontal disease with less than 25% horizontal bone loss at the mesial root of the right mandibular first molar. b. Radiograph of established periodontitis revealing decreased alveolar bone height of the buccal or lingual alveolus of the mandibular first molar. c. Moderate periodontitis with less than 50% angular (vertical) bone loss at the right mandibular canine. d. Established periodontitis of the distal root of the right mandibular first molar. e. Advanced periodontitis with marked horizontal bone loss.

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Feline Dentistry

d

c

e Figure 3.34 Continued

both the buccal and lingual plates of bone, as well as interdental bone, have been resorbed. Clinically, horizontal bone loss is typified by a suprabony pocket, which occurs when the epithelial attachment is above the bony defect.

Vertical bone loss, resulting from infrabony defects, occurs when the walls of the pocket are within a bony housing. Periodontal disease may cause a vertical defect to extend apically from the alveolar margin. At first, the defect is surrounded by three walls of bone: two mar-

Radiology

ginal (lingual/palatal and facial) and a hemisepta (the bone of the interdental septum that remains on the root of the uninvolved adjacent tooth). As disease progresses, two-, one-, and no-walled (cup) defects may occur. Radiographically, vertical bone defects are generally V-shaped and sharply outlined. Stage 4, advanced periodontal disease, is typified by deep pockets and/or marked gingival recession, tooth mobility, gingival bleeding, and purulent discharge. Attachment loss is greater than 50% of the root length (figs. 3.34 d, e). Furcation exposure results from bone loss at the root junction of multirooted teeth because of advanced periodontal disease. It is sometimes difficult to determine radiographically whether the interradicular space is involved, unless there is a radiolucent area in the region of the furcation. Lack of radiographically detectable furcation involvement is not confirmation of the absence of periodontal destruction. Advanced furcation exposures where both cortical plates are resorbed are easily recognized on radiographs.

•

•

•

71

a

Stage 1 furcation involvement exists when the tip of a probe can just enter the furcation area. Bone partially fills the area where the roots meet. Radiographically, there may be decreased opacity of the bone at the furcation. Stage 2 furcation involvement exists when the probe tip extends horizontally into the area where the roots converge but does not exit on the other side. Radiographically, there will be bone loss at the furcation (fig. 3.35a). Stage 3 furcation exposure lesions exist secondary to advanced periodontal disease. Alveolar bone has resorbed to a point that an explorer probe passes through the defect unobstructed. Radiographically, there will be an area of complete bone loss (fig. 3.35b).

Alveolar Bone Expansion (Chronic Alveolar Osteitis) Alveolar bone expansion clinically appears as bulging alveoli around one or both maxillary and/or mandibular canines. Radiographically, this lesion appears as bone loss around the root and expansile alveolar bone growth (figs. 3.36 a, b, c, d).

Tooth Extrusion Tooth extrusion (also called supereruption) occurs when one or more of the intact canine teeth appear longer than normal. Radiographically, the affected teeth have marked loss of periodontal support (figs. 3.37 a, b).

b Figure 3.35 a. Stage 2 furcation involvement. b. Stage 3 furcation exposure.

a

b

c

d

Figure 3.36 a. Clinical alveolar bone expansion. b. Radiograph image of the bone expansion. c. Bilateral maxillary canine alveolar bone expansion with abnormal extrusion of the left maxillary canine. d. Radiograph of bulging bone surrounding the maxillary canines.

a

Figure 3.37 a. Left mandibular canine tooth extrusion. b. Radiograph confirming advanced periodontal disease.

72

b

Radiology

73

Figure 3.39 Ankylosis and replacement resorption of both mandibular canine tooth roots.

extent of endodontic disease. The pulp is contained within the chamber and canal portions of the tooth. Pulp tissue appears radiolucent radiographically. The radiograph of an endodontically affected tooth is examined for the following: Figure 3.38 Hypercementosis around the mandibular canine apex (image courtesy Dr. Barry Rathfon).

• • •

Hypercementosis Hypercementosis appears as excessive deposition of cementum, usually at the apical third of the root in response to chronic inflammation or abnormal occlusal forces (fig. 3.38).

Ankylosis Ankylosis is the union of cementum with the alveolar bone through destruction of the periodontal ligament. The tooth root becomes fused to the alveolar wall. Radiographically, there will be little or no periodontal ligament space (fig. 3.39).

Endodontic Disease Radiography is essential for evaluation of a tooth affected by endodontic disease. Radiographic images of the teeth and tissues around the root help to define the

•

Apical closure, which is necessary for conventional endodontic therapy Tooth fracture Abnormalities in the root canal, such as obstruction or resorption Periapical pathology, such as widened periodontal ligament space at the tooth’s apex secondary to bone resorption

Periapical disease is a pathologic process surrounding the apex of one or more roots that is due to either inflammation or necrosis of the dental pulp from trauma or infection, or occurs as an extension of periodontal disease. The radiographic appearance of periapical disease consistent with a granulomatous lesion (periapical granuloma) is a widening of the apical periodontal ligament space with circumscribed alveolar bone resorption. In the early stages of abscess formation, bony changes are not radiographically present. A homogeneous radiolucency at the apex or a dark halo in the periapical tissues is typical of an abscess. A sharply outlined circumscribed radiolucent area is commonly caused by a periapical cyst, which usually arises from preexisting granulomas (figs. 3.40 a, b; 3.41 a, b; 3.42 a, b; 3.43 a, b).

a

a

b Figure 3.40 a. Inflammation around the distal root of the right mandibular first molar. b. Radiographic appearance of periapical cyst secondary to root pathology.

b Figure 3.41 a. Enlarged pulp cavity and periapical lucency consistent with pulp necrosis mandibular canine. b. Periapical lucency and ill-defined periapical periodontal ligament of fractured tooth.

74

a

a

b Figure 3.43 a. A markedly enlarged pulp cavity due to pulp exposure soon after the permanent tooth erupted, b. Cut section of tooth after extraction.

b Figure 3.42 a. Complicated fracture of the left maxillary canine. b. Circumscribed apical bone resorption consistent with periapical granuloma.

75

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Feline Dentistry

Figure 3.44 External root resorption with periapical lucency.

External root resorption may also result from periapical inflammation, orthodontic therapy, or from unknown stimuli. Radiographically, external resorption appears as radiolucent defects on any area of the root surface (fig. 3.44). Internal resorption arises from the pulp. The cause is unknown, but trauma or pulpitis from anachoresis (bacteria gaining access to the injured pulp through vascular channels) are believed to be contributing factors. A dead pulp cannot cause internal resorption (fig. 3.45). Often, it is difficult to determine whether a lesion is due to internal or external resorption. If a normalappearing root canal is visualized radiographically, the lesion is considered external in origin.

Figure 3.45

•

•

Tooth Resorption Tooth resorption is classified as the following:

•

Stage 1 (TR 1): Mild dental hard tissue loss (cementum or cementum and enamel).

•

Internal root resorption.

Stage 2 (TR 2): Moderate dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does not extend to the pulp cavity) (figs. 3.46 a, b, c) Stage 3 (TR 3): Deep dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth retains its integrity. Internal resorption radiographically appears as focal enlargement of the root canal (figs. 3.47 a, b). Stage 4 (TR 4): Extensive dental hard tissue loss (cementum or cementum and enamel with loss of

b

a

c Figure 3.46 a. Radiograph of Stage 2 tooth resorption lucency in the mid-root area. b. Stage 2 tooth resorption affecting the cementum and dentin. c. Stage 2 tooth resorption approaching the pulp cavity.

77

78

Feline Dentistry

a

b

Figure 3.47 a. Stage 3 tooth resorption radiographic image. b. Extracted third incisor.

•

dentin that extends to the pulp cavity); most of the tooth has lost its integrity. a. Crown and root are equally affected (fig. 3.48a). b. Crown is more severely affected than the root (fig. 3.48b). c. Root is more severely affected than the crown (fig. 3.48c). Stage 5 (TR 5): Remnants of dental hard tissue are visible only as irregular radiopacities, and gingival covering is complete (fig. 3.49).

In addition to the above classification, some investigators believe that three radiographic appearances of tooth resorption should be distinguished in order to create a treatment plan based on clinical and radiographic findings (fig. 3.50): On a radiograph of a tooth with type 1 appearance, a focal or multifocal radiolucency is present in the tooth with otherwise normal radiopacity and normal periodontal ligament space (fig. 3.51).

On a radiograph of a tooth with type 2 appearance, there is narrowing or disappearance of the periodontal ligament space in at least some areas and decreased radiopacity of part of the tooth (fig. 3.51). On a radiograph of a tooth with type 3 appearance, features of both type 1 and type 2 are present in the same tooth. A tooth with this appearance has areas of normal and narrow or lost periodontal ligament space, and there is focal or multifocal radiolucency in the tooth and decreased radiopacity in other areas of the tooth (fig. 3.52).

Neoplastic Disease Neoplasia in the oral cavity may only affect the soft tissues or extend into hard tissue of the skull. Radiographic signs of oral neoplasia in the cat include invasion of the mandible or maxilla with sclerosis, periosteal proliferation, osteolysis and displacement of the locally affected teeth. Occasionally, the teeth will appear to be floating (figs. 3.53 a, b; 3.54 a, b).

a

b

c

Figure 3.48 a. Stage 4a tooth resorption. b. Stage 4b tooth resorption. c. Stage 4c tooth resorption.

Figure 3.49

Stage 5 tooth resorption.

79

Type 1

Type 2 Figure 3.51 Types 1 and 2 tooth resorption.

Type 3

Figure 3.50 Illustrations of radiographic tooth resorption types. Figure 3.52 Type 3 tooth resorption (mesial root type 1, distal root type 2).

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Radiology

81

TMJ Disease

Traumatic Jaw Injury

Luxation of the TMJ is due to trauma or congenital malformation. Usually the mandibular condyle is luxated rostrodorsally, resulting in malocclusion. When there is a fracture of the retroarticular process, a caudal luxation is possible. Ankylosis of the TMJ is a rare condition in the usually young cat that occurs most commonly from previous trauma. Radiographic features include loss of the TMJ space and irregular new bone formation.

Jaw fractures should be evaluated radiographically to help determine a therapy plan. Often the fracture line will include a tooth that should be extracted. Normal breed variations of the mandibular symphysis should not be confused with a fracture that needs therapy (figs. 3.55 a, b).

a

b Figure 3.53

a. Clinical appearance of squamous cell carcinoma affecting the left maxilla. b. Radiographic image of advanced squamous cell carcinoma.

b

a Figure 3.54 a. Lateral oblique radiograph of the left mandible affected by squamous cell carcinoma. b. Lateral radiographic image of squamous cell carcinoma.

a

b

Figure 3.55 a. Normal left temporomandibular joint. b. Fracture of the right temporal bone and condylar process.

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Radiology

Further Reading Bar-Am Y, Pollard RE, Kass PH, Verstraete FJ. The diagnostic yield of conventional radiographs and computed tomography in dogs and cats with maxillofacial trauma. Vet Surg 2008; 37: 294–299. Baxter CJK. Oral and dental diagnostics. In: Tutt C, Deeprose J, Crossley D. BSAVA Manual of Canine and Feline Dentistry, 3rd ed. BSAVA, Gloucester, 2007; 22–40. Bellows J. Radiographic signs and diagnosis of dental disease. Sem Vet Med Surg Small Anim 1993; 8: 138–145. DeForge DH, Colmery BH. An Atlas of Veterinary Dental Radiology. Iowa State University Press, Ames, 2000. DuPont GA, DeBowes LJ. Atlas of Dental Radiography in Dogs and Cats. Saunders-Elsevier, Philadelphia, 2009. Eisner ER. Oral-dental radiographic examination technique. Vet Clin North Am Small Anim Pract 1998; 28: 1063–1087. Gorrel C. Radiographic evaluation. Vet Clin North Am Small Anim Pract 1998; 28: 1089–1110. Harvey CE, Flax BM. Feline oral-dental radiographic examination and interpretation. Vet Clin North Am Small Anim Pract 1992; 22: 1279–1295. Harvey EE, Emily PP. Oral examination and diagnostic techniques. Small Animal Dentistry, Mosby, St. Louis, 1993; 19–41.

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Holmstrom SE, Frost Fitch P, Eisner ER. Dental radiology. Veterinary Dental Techniques for the Small Animal Practitioner, 3rd ed. Saunders, Philadelphia, 2004; 131–174. Lommer MJ, Verstraete FJ. Radiographic patterns of periodontitis in cats: 147 cases (1998–1999). J Am Vet Med Assoc 2001; 218: 230–234. Mulligan TW, Aller MS, Williams CA. Atlas of Canine and Feline Dental Radiography. Veterinary Learning Systems, Trenton, 1998. Niemiec BA. Dental radiographic interpretation. J Vet Dent 2005; 22: 53–59. Niemiec BA, Furman R. Feline dental radiography. J Vet Dent 2004; 21: 252–257. Niemiec BA, Gilbert T, Sabatino D. Equipment and basic geometry of dental radiography. J Vet Dent 2004; 21: 48–52. Niemiec BA, Sabatino D, Gilbert T. Developing dental radiographs. J Vet Dent 2004; 21: 116–121. Schwarz T, Weller R, Dickie AM, Konar M, Sullivan M. Imaging of the canine and feline temporomandibular joint: a review. Vet Radiol Ultrasound 2002; 43: 85–97. Verstraete FJM, Kass PH, Terpak CH. Diagnostic value of fullmouth radiography in cats. Am J Vet Res 1998; 59: 692–695. Verstraete FJM, Kass PH, Terpak CH. Routine use of fullmouth radiographs in the dog and cat. Praktische Tierarzt 2001; 82: 658–667.

Chapter 4

Charting

Dental charting provides a graphic report of the cat’s teeth and mouth. A blank dental chart depicts anatomically correct maxillary and mandibular teeth with space to note abnormalities. Charting provides a place to record examination findings in order to develop an accurate and comprehensive treatment plan, as well as a thorough record of past treatments. To evaluate each tooth individually for charting, complete immobilization (general anesthesia) is necessary. The mouth is generally charted before scaling and can be recharted when a significant amount of calculus has been removed. Chart formats vary from paperless electronic files incorporated in proprietary veterinary software programs to handwritten paper forms (see examples at end of chapter). Whichever system is used, the dental chart should include areas to record the dental history; skull type (brachycephalic, mesaticephalic, dolichocephalic); oral pathology, including the amount and location of plaque and calculus; probing depths; fractured and mobile teeth; oral masses; and radiographic findings. Additionally, therapy provided, therapy recommended but not provided, and the future treatment plan and home care instructions should be noted on the dental chart and medical record.

maxillary quadrant is completed. The right mandibular quadrant (400 series) follows, the endotracheal tube attachment to the anesthetic machine is detached, and the animal’s body and head are rotated for evaluation and charting of the 200 and 300 series. Each tooth is examined completely, including periodontal probing, before the next tooth is viewed. Only abnormalities are noted on the dental chart (figs. 4.1 a, b).

Charting Steps

10.

Four-handed (two person) charting is the fastest and most efficient. One person examines the mouth and the other records information on the chart. The examiner begins by saying “100 series” and “101” (which is the maxillary right first incisor according to the modified Triadan system of tooth identification), noting any abnormalities and then moving distally until the right 84

1.

2.

3. 4.

5. 6. 7. 8. 9.

11.

12.

Examine the occlusion rostrally and caudally before intubation and record any abnormalities. Normally, the teeth of the opposing arches in cats do not touch. After intubation, examine the mouth for missing teeth and circle all visibly missing teeth on the dental chart. The most commonly missing tooth is the mandibular third premolar. Record obviously fractured teeth. Check for tooth mobility using an instrument handle pressed against the tooth. Record abnormal mobility (M1, M2, M3). Record areas of calculus accumulation. Record abnormal probing depths or attachment levels around each tooth. Expose and process dental radiographs. Scale and polish the teeth. Reprobe if a significant amount of calculus was removed. Formulate a treatment plan through tooth-by-tooth evaluation; draw a diagonal line through teeth that need to be extracted. Calculate fees for the treatment plan and contact the owner for approval while the technician is completing the teeth cleaning process. Once the owner approves, perform needed therapy and record all care on the dental chart (figs. 4.2–4.7).

Charting

a Figure 4.1

b a. Two-handed charting. b. Four-handed dentistry.

Charting Abbreviations The following abbreviations (in alphabetical order) were adapted from the American Veterinary Dental College (AVDC): AB

Abrasion

APG

Apexogenesis

F/AR

Apically repositioned periodontal flap

APX

Apexification

F/CR

Coronally repositioned periodontal flap

AT

Attrition

F/L

Lateral sliding periodontal flap

B

Biopsy

FGG

Free gingival graft

B/E

Biopsy excisional

FRE

Frenoplasty (frenotomy, frenectomy)

B/I

Biopsy incisional

FX

Fracture (tooth or jaw)

F

Flap

BG

Bone graft (includes placement of bone substitute or bone stimulant material)

FX/R

Repair of jaw fracture

C

Canine

FX/R/P

Pin repair of jaw fracture

CBU

Core build-up

FX/R/PL

Plate repair of jaw fracture

CFL

Cleft lip

FX/R/S

Screw repair of jaw fracture

Cleft lip repair

FX/R/WIR

Wire repair of jaw fracture

Cleft palate

FX/R/WIR/C

Cerclage wire repair of jaw fracture

Cleft palate repair

FX/R/WIR/ID

Interdental wire repair of jaw fracture

CR

Crown

FX/R/WIR/OS

Osseous wire repair of jaw fracture

CRA

Crown amputation

CFL/R CFP CFP/R

CR/M

For tooth fracture abbreviations, see under T/FX

G

Granuloma

Crown metal

G/B

Buccal granuloma (cheek-chewing lesion)

CRR

Crown reduction

G/L

Sublingual granuloma (tongue-chewing lesion)

DT

Deciduous (primary) tooth

G/E/L

Eosinophilic granuloma—lip

DTC

Dentigerous cyst

G/E/P

Eosinophilic granuloma—palate

E

Enamel

G/E/T

Eosinophilic granuloma—tongue

E/D FB

Enamel defect Foreign body

GH

Gingival hyperplasia/hypertrophy

85

GR

Gingival recession

OM/PAP

Papillomatosis

GTR

Guided tissue regeneration

OM/SCC

Squamous cell carcinoma

GV

Gingivoplasty (gingivectomy)

IM

Impression and model

IO

Interceptive (extraction) orthodontics

OR

Orthodontic recheck

IO/D

Deciduous (primary) tooth interceptive orthodontics

OST

Osteomyelitis

IO/P

Permanent (secondary) tooth interceptive orthodontics

PC

Pulp capping

IP

ONF

Oronasal fistula ONF/R

Inclined plane

Oronasal fistula repair

PC/D

Direct pulp capping

PC/I

Indirect pulp capping

IP/AC

Acrylic inclined plane

IP/C

Composite inclined plane

PD0

Normal periodontium

IP/M

Metal (i.e., lab-produced) inclined plane

PD1

Gingivitis only

Laceration

PD2

50% attachment loss

LAC/T

Laceration tongue

PE

Pulp exposure

Malocclusion

PRO

MAL/1

Class I malocclusion (normal jaw relationship, specific teeth are incorrectly positioned)

Periodontal prophylaxis (examination, scaling, polishing, irrigation)

R

Restoration of tooth

MAL/2

Class II malocclusion—mandibular distoclusion (mandible shorter than maxilla)

R/C

Restoration with composite

MAL/3

Class III malocclusion—mandibular mesiocluson (maxilla shorter than mandible)

R/CP

Restoration with compomer

R/I

Restoration with glass ionomer

MAL/LV

Linguoversion mandibular canine tooth

RAD

Radiograph

MAL/RXB

Rostral crossbite

RC

Root canal therapy

MAL/CXB

Caudal crossbite

LAC

MAL

PDI

Periodontal disease index

RC/S

Surgical root canal therapy

MAL/MA

Maxillary-mandibular asymmetry

RD

MN/FX

Mandibular fracture

RPC

Root planing—closed

Maxilla or maxillary

RPO

Root planing—open

MX/FX

Maxillary fracture

RR

Internal root resorption

OA

Orthodontic appliance

RRT

Retained root tip

OAA

Adjust orthodontic appliance

RTR

Retained tooth root

OA/BKT

Bracket orthodontic appliance

S

Surgery

OA/BU

Button orthodontic appliance

S/M

Mandibulectomy

OA/EC

Elastic (power chain) orthodontic appliance

S/P

Palate surgery

OA/WIR

Wire orthodontic appliance

S/X

Maxillectomy

MX

Retained deciduous (primary) tooth

Install orthodontic appliance

SC

Subgingival curettage

OAR

Remove orthodontic appliance

SN

Supernumerary

OC

Orthodontic/genetic consultation

SPL

Splint

OM

Oral mass

SPL/AC

Acrylic splint

OM/AD

Adenocarcinoma

SPL/C

Composite splint

OM/EPA

Acanthomatous ameloblastoma (epulis)

SPL/WIR

Wire-reinforced splint

OAI

86

OM/EPF

Fibromatous epulis

OM/EPO

Ossifying epulis

OM/FS

Fibrosarcoma

ST

Stomatitis ST/CU ST/FFS

SYM

Stomatitis—contact ulcers Stomatitis—feline caudal stomatitis Symphysis

OM/LS

Lymphosarcoma

OM/MM

Malignant melanoma

SYM/S

Symphyseal separation

OM/OS

Osteosarcoma

SYM/WIR

Wire repair of symphyseal separation

T

Tooth

Tooth resorption lesion

Avulsed tooth

TR1

Tooth resorption into enamel only

T/FX

Fractured tooth (see next seven listings for fracture types)

TR2

Tooth resorption into dentin

TR3

Tooth resorption into pulp or root canal

T/FX/EI

Enamel infraction

TR4a

Marked hard tissue resorption of crown and root

T/FX/EF

Enamel fracture

TR4b

T/FX/UCF

Uncomplicated crown fracture

Marked hard tissue resorption of crown more than root

T/FX/CCF

Complicated crown fracture

TR4c

T/FX/UCRF

Uncomplicated crown-root fracture

Marked hard tissue resorption, affecting root more than crown

T/FX/CCRF

Complicated crown-root fracture

TR5

Crown lost, root tips remain

T/FX/RF

Root fracture

TMJ/R

Reduction of TMJ luxation

T/I

Impacted tooth

TRX

Tooth partial resection (e.g., hemisection)

T/LUX

Luxated tooth

VP

Vital pulp therapy

T/NE

Near pulp exposure

X

Simple closed extraction of a tooth

T/NV

Nonvital tooth

XS

Extraction with tooth sectioning, nonsurgical

Pulp exposure

XSS

Surgical (open) extraction of a tooth

T/PE TP

TR

T/A

Treatment plan

87

Date:

Pet’s Name: Breed:

Age:

Sex:

Medical Alert: Presenting Complaint:

Procedure Record

110

108

104

204

208

210

Signs:

Diagnosis:

Treatment:

Clean / Polish / Fluoride:

Routine

Extended

Root Planing /Packing: X-rays: Comments: Antibiotics Dispensed: Pain Medications:

Maxilla Inj:

Right

Dispensed:

Diet:

Left

Mandible

Home Care:

Recheck:

Abbreviation Key AL AT CA CWD ED EP FE FX GH GV/GP LPS M O OP

Attachment Loss Attrition Caries Crowding Enamel Defect Epulis Furcation Exposure Fracture Gingival Hyperplasia Gingivectomy/Plasty Lymphocytic, Plasmacytic, Stomatitis Mobile Tooth Missing Tooth Odontoplasty

OM ONF PE PP RD RE RL ROT RPC RPO RTR X XS XSS

Oral Mass Oronasal Fistula Pulp Exposure Periodontal Pocket Retained Deciduous Root Exposure Resorptive Lesion Rotated Tooth Root Planing, Closed Root Planing, Open Retained Root Extraction Extraction, Sectioned Extraction, Surgical

411

409

404

304

309

311

*Notice: This product license is conditional. Efficacy and/or potency of this product have not been fully demonstrated.

a Figure 4.2

88

Antirobe® and Clavamox® are registered trademarks and Doxirobe™ is a trademark of Pfizer Animal Health. Adapted with permission of Johnathon R. Dodd. DVM. FAVD. Dip. AVDC and Robert B. Wiggs. DVM. FAVD. Dip. AVDC. © 2007 Pfizer Inc

PFE1106008

a. Blank Pfizer feline dental chart. b. Completed chart (courtesy of Dr. Heidi Loprise).

Date:

Pet’s Name: Breed:

Age:

Sex:

Medical Alert: Presenting Complaint:

Procedure Record Signs: 109

108

107 104

204 207

208

209

Diagnosis:

Treatment:

Clean / Polish / Fluoride:

Routine

Extended

Root Planing /Packing: X-rays: Comments: Antibiotics Dispensed: Pain Medications:

Inj: Dispensed:

Maxilla Diet:

Right

Home Care:

Left

Mandible

Recheck:

Abbreviation Key AL AT CA CWD ED EP FE FX GH GV/GP LPS M O OP

Attachment Loss Attrition Caries Crowding Enamel Defect Epulis Furcation Exposure Fracture Gingival Hyperplasia Gingivectomy/Plasty Lymphocytic, Plasmacytic, Stomatitis Mobile Tooth Missing Tooth Odontoplasty

OM ONF PE PP RD RE RL ROT RPC RPO RTR X XS XSS

Oral Mass Oronasal Fistula Pulp Exposure Periodontal Pocket Retained Deciduous Root Exposure Resorptive Lesion Rotated Tooth Root Planing, Closed Root Planing, Open Retained Root Extraction Extraction, Sectioned Extraction, Surgical

409

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Antirobe® and Clavamox® are registered trademarks of Pfizer Animal Health. Adapted with permission of Johnathon R. Dodd. DVM. FAVD. Dip. AVDC and Robert B. Wiggs. DVM. FAVD. Dip. AVDC. © 2007 Pfizer Inc

b

PFE1106008

Figure 4.2 Continued

89

90 a Figure 4.3

a. Blank peel-off dental chart. b. Abbreviation key. c. Completed dental chart (DentaLabels).

b

c Figure 4.3 Continued

91

92 Figure 4.4 AVImark paperless computer generated and stored dental chart.

Examination Findings 109

Figure 4.5

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ST — Stomatitis ST/CU – Stomatitis – contact ulcers ST/FFS – Stomatitis – feline faucitis-stomatitis SYM — Symphysis SYM/S – Symphyseal separation T — Tooth T/A – Avulsed tooth T/FX – Fractured tooth (see next seven listings for fracture types) T/FX/EI – Enamel infraction T/FX/EF – Enamel fracture 104 204 T/FX/UCF – Uncomplicated crown fracture T/FX/CCF – Complicated crown fracture 106 206 T/FX/UCRF – Uncomplicated crown-root 107 207 fracture T/FX/CCRF – Complicated crown-root fracture 108 208 T/FX/RF – Root fracture T/I – Impacted tooth T/LUX – Luxated tooth 109 209 T/NE – Near pulp exposure T/NV – Non-vital tooth T/PE – Pulp exposure T/V – Vital tooth TMJ — Temporomandibular joint TMJ/D – TMJ dysplaisia TMJ/FX – TMJ fracture TMJ/LUX – TMJ luxation TP — Treatment plan 409 309 TR — Tooth resorption lesion TR1 – TR Stage 1: mild 408 308 dental hard tissue loss (cementum or cementum and enamel). 307 407 TR2 – TR Stage 2: moderate dental hard tissue loss (cementum or cementum and enamel with loss of dentin that does not 304 extend to the pulp cavity). 404 TR3 – TR Stage 3: Deep dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth retains its integrity. TR4 – TR Stage 4: Extensive dental hard tissue loss (cementum or cementum and enamel with loss of dentin that extends to the pulp cavity); most of the tooth has lost its integrity. TR4a – Crown and root are equally affected. 409 408 407 404 403 402 401 301 302 303 304 307 308 309 TR4b – Crown is more severely affected than the root. TR4c – Root is more RAD — Radiograph PD1 – Gingivitis only OM/EPF – Fibromatous epulis OM/SCC – Squamous cell severely affected than the OM/EPO – Ossifying epulis carcinoma PD2 50% attachment loss OM/MM – Malignant RR — Internal root resorption OST — Osteomyelitis tissue are visible only as PE — Pulp exposure melanoma RRT — Retained root tip PDI — Periodontal disease irregular radiopacities, PM1,2,3,4 — Premolar OM/OS – Osteosarcoma index RTR — Retained tooth root and gingival covering is teeth OM/PAP – Papillomatosis complete PD0 – Normal periodontium SN — Supernumerary 403 402 401 301 302 303

AB — Abrasion AT — Attrition C — Canine CA — Caries CFL — Cleft lip CFP — Cleft palate CMO — Cranio-mandibular osteopathy DT — Deciduous (primary) tooth DTC — Dentigerous cyst E – Enamel E/D – Enamel defect E/H – Enamel hypocalcification or hypoplasia FB — Foreign body FX — Fracture (tooth or jaw). For tooth fracture abbreviations, see under T/FX G — Granuloma G/B – Buccal granuloma (cheek chewing lesion) G/L – Sublingual granuloma (tongue chewing lesion) G/E/L – Eosinophilic granuloma – lip G/E/P – Eosinophilic granuloma – palate G/E/T – Eosinophilic granuloma – tongue GH — Gingival hyperplasia/ hypertrophy GR — Gingival recession L1,2,3 — Incisor teeth LAC — Laceration LAC/B – Laceration buccal (cheek) LAC/L – Laceration lip LAC/T – Laceration tongue M1,2,3 — Molar teeth MAL — Malocclusion MAL/1 – Class 1 malocclusion (normal jaw relationship, specific teeth are incorrectly positioned) MAL/2 – Class 2 malocclusion – mandibular distoclusion (mandible shorter than maxilla) MAL/3 – Class 3 malocclusion - mandibular mesiocluson (maxilla shorter than mandible) MAL/1-3/BV – Buccoversion MAL/1-3/CXB – caudal crossbite MAL/1-3/DV – Distoversion MAL/1-3/LABV – Labioversion MAL/1-3/LV – Linguoversion MAL/1-3/MV – Mesioversion MAL/1-3/OB – Open bite MAL/RXB – Rostral crossbite MAL/1-3/XB – Crossbite, see CXB or RXB (do not use “wry bite” or WRY) MN — Mandible or mandibular MN/FX – Mandibular fracture MX — Maxilla or maxillary MX/FX – Maxillary fracture OC — Orthodontic/genetic consultation OM — Oral mass OM/AD – Adenocarcinoma OM/EPA – Acanthomatous ameloblastoma (epulis)

108

Dental charts with American Veterinary Dental College abbreviations.

93

Treatment Provided

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409 Figure 4.5 Continued

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APG — Apexogenesis APG — Apexification B — Biopsy B/E – Biopsy excisional B/I – Biopsy incisional BG — Bone graft (includes placement of bone substitute or bone stimulant material) CBU — Core build up CFL/R — Cleft lip repair CFP/R — Cleft palate repair CR — Crown CRA — Crown amputation CR/M – Crown metal CRL — Crown lengthening CR/PFM – Crown porcelain fused to metal CR/P – Crown preparation CRR — Crown reduction CS — Culture/susceptibility F — Flap F/AR – Apically repositioned periodontal flap F/CR – Coronally repositioned periodontal flap F/L – Lateral sliding periodontal flap FGG — Free gingival graft FRE — Frenoplasty (frenotomy, frenectomy) FX/R – Repair of jaw fracture FX/R/P – Pin repair of jaw fracture FX/R/PL – Plate repair of jaw fracture FX/R/S – Screw repair of jaw fracture FX/R/WIR – Wire repair of jaw fracture FX/R/WIR/C – Cerclage wire repair of jaw fracture FX/R/WIR/ID – Interdental wire repair of jaw fracture FX/R/WIR/OS – Osseous wire repair of jaw fracture GTR — Guided tissue regeneration GV — Gingivoplasty (gingivectomy) IM — Impression and model IMP — Implant IO — Interceptive (extraction) orthodontics IO/D – Deciduous (primary) tooth interceptive orthodontics IO/P – Permanent (secondary) tooth interceptive orthodontics IP — Inclined plane IP/AC – Acrylic inclined plane

408

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403 402 401 301 302 303

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IP/C – Composite inclined plane IP/M – Metal (i.e., lab produced) inclined plane OA — Orthodontic appliance OAA — Adjust orthodontic appliance OA/BKT – Bracket orthodontic appliance OA/BU – Button orthodontic appliance OA/EC – Elastic (power chain) orthodontic appliance OA/WIR – Wire orthodontic appliance OAI — Install orthodontic appliance OAR — Remove orthodontic appliance PC — Pulp capping PC/D – Direct pulp capping PC/I – Indirect pulp capping PRO — Periodontal prophylaxis (examination, scaling, polishing, irrigation) R — Restoration of tooth R/C – Restoration with composite R/CP – Restoration with compomer R/I – Restoration with glass ionomer RC — Root canal therapy RC/S – Surgical root canal therapy RPC — Root planing – closed RPO — Root planing – open S — Surgery S/M – Mandibulectomy S/P – Palate surgery S/X – Maxillectomy SC — Subgingival curettage SPL — Splint SPL/AC – Acrylic splint SPL/C – Composite splint SPL/WIR – Wire reinforced splint SYM/WIR – Wire repair of symphyseal separation TMJ/C — Temporomandibular joint condylectomy TMJ/R — Reduction of TMJ luxation TRX — Tooth partial resection (e.g., hemisection) VP — Vital pulp therapy X — Simple closed extraction of a tooth XS — Extraction with tooth sectioning, non-surgical XSS — Surgical (open) extraction of a tooth

VHUP DENTAL RECORD

Date:

Copyright: Veterinary Hospital of the University of Pennsylvania

R

L

Staff: (circle primary staff) Chief Complaint: Awake

Sedated

MAL/1 MAL/2 MAL/3 MAL/WRY MAL/BN Malocclusion/base narrow mand. canines MAL/ABX, PBX Mal/anterior, posterior crossbite SN Supernumerary tooth DT Deciduous tooth RD Retained deciduous tooth PD0 No perio dx (maybe calculus) PD1 Gingivitis (no bone loss) PD2 Mild periodontitis (< 25% attach loss) PD3 Mod periodontitis (< 50% attach loss) PD4 Severe periodontitis (> 50% attach loss) GH Gingival hyperplasia / enlargement GR Gingival recession ST Stomatitis ST/CU Stomatitis – contact ulcer ST/FFS Stomatitis – Feline faucitis-stomatitis OM Oral mass: OM/EPA OM/EPF OM/EPO OM//MM OM/FS OM/SCC OM/OS OM/AD OM/LS OM/PAP DTC Dentigerous cyst O Missing tooth OTH Other

Anesthetized AT / AB E/D, H CA TR

Attrition/abrasion Enamel/defect, hypoplasia Caries Tooth Resorption (Grade) 1, 2, 3, 4, 5 RR Internal root resorption RTR Retained tooth root RRT Retained root tip T/A, I, LUX Tooth/ avulsed, impacted, luxated T/FX Tooth Fracture ( EI, EF, UCF, CCF, UCRF, CCRF, RF ) T/NV, V Tooth/non-vital, vital G/B, L Granuloma/buccal, sublingual G/E/L, P, T Eosinophilic gran./lip, palate, tongue FB Foreign body OST Osteomyelitis LAC/B, L, T Laceration/buccal, lip, tongue MN/FX MX/FX Jaw fractures SYM/S Symphyseal separation CFP CFL Cleft palate, Cleft lip ONF Oronasal fistula CMO Cranio-Mandibular Osteopathy TMJ/D, FX, LUX TMJ/dysplasia, fracture, luxation

N A - Extraoral/facial

N A – Lymph nodes

N A – Buccal mucosa

N A – Tongue

N A – Palate

N A – Tonsils

N A – Pharynx Tooth

M1

P4

P3

P2

C

I3

I2

I1

I1

I2

I3

C

P2

P3

P4

M1

Triadan

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Tooth

M1

P4

P3

C

I3

I2

I1

I1

I2

I3

C

P3

P4

M1

Triadan

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Mobility Recession Pocket Furcation Hyperplasia Calculus Plaque Gingivitis

Mobility Recession Pocket Furcation Hyperplasia Calculus

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Plaque Gingivitis

a 95

Figure 4.6

Dental charts (courtesy of Dr. Alex Rieter, University of Pennsylvania).

96

R

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L

RAD Rads (Dental, CDR, CT Scan, Plain Film) Y Photos (Digital, 35 mm) B/I B/E Biopsy – incisional/excisional CS Culture/Susceptibility OC Orthodontic/Genetic Consultation OR Orthodontic Recheck ------------------------------------------------------------------------PRO Periodontal prophylaxis SC Subgingival curettage Bone Curettage RPC Closed root planing RPO Open root planing GV Gingivoplasty Alveoloplasty F/AR Apical repositioning flap F/CR Coronal repositioning flap F/L Lateral sliding periodontal flap CRL Crown lengthening BG Bone graft GTR Guided tissue regeneration FGG Free gingival graft SPL/AC, C, WIR Splint/acrylic, composite, wire reinforced ------------------------------------------------------------------------RC Root canal therapy RC/S Surgical root canal therapy RRX Root resection (crown intact) TRX Tooth partial resection (hemisection) CRR Crown reduction VP Vital pulp therapy PC/D PC/I Direct/indirect pulp capping CRA Crown amputation APX Apexification APG Apexogenesis ------------------------------------------------------------------------R/C, I, A Restoration/composite, GI, amalgam IMP Implant ------------------------------------------------------------------------F Flap X Extr. - closed, no sectioning XS Extr. – closed, w/ sectioning XSS Extr. – open IO/P IO/D Intercept ortho (perm/dec) ONF/R Oronasal fistula repair CFP/R Cleft palate repair CFL/R Cleft lip repair S/P Palate surgery S/M Mandibulectomy S/X Maxillectomy FRE Frenoplasty SYM/WIR Symphyseal separation/wiring FX/R Jaw fracture repair (j. fx. rp.) FX/R/P Pin j. fx. rp. FX/R/PL Plate j. fx. rp. FX/R/S Screw j. fx. rp FX/R/WIR Wire j. fx. rp. FX/R/WIR/C Cerclage wire j. fx. rp. FX/R/WIR/ID Interdental wire j. fx. rp FX/R/WIR/OS Osseous wire j. fx. rp TMJ/C TMJ condylectomy TMJ/R Reduction of TMJ luxation ------------------------------------------------------------------------CBU Core build up CR/P Crown preparation CR/M Crown metal CR/PFM Crown porcelain fused to metal IM Impressions/models IP/AC, C, M Inclined plane/acrylic, composite, metal OAI Ortho appliance – install OAA Ortho appliance – adjust OAR Ortho appliance – remove OA/BKT, BU Ortho app./bracket, button OA/EC, WIR Ortho app./elastic, wire

Nerve Block 0.5% Marcaine Infraorbital Inferior Alveolar Mental Maxillary

RIGHT

LEFT ml ml ml ml

ml ml ml ml

Treatment:

Instructions and medications:

Follow-up:

OTH:

b Figure 4.6 Continued

Copyright: Veterinary Hospital of the University of Pennsylvania

U of MN Dental Record

Feline Dental Record R

L

Date: Staff:

Chief Complaint:

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AT/AB – attrition/abrasion CU/B, T, PLT – ulcer on cheek/tongue/ palate DTC – dentigerous cyst FX – tooth fracture: EI/EF/UCF/CCF/ UCRF/CCRF/RF GH – gingival hyperplasia/hypertrophy JVG – juvenile gingivitis LAC/B/L/T – laceration cheek/lip/tongue MAL – Mal 1, Mal 2, Mal 3 MAL/WRY – wry bite MN/FX, MX/FX, SYM/S – fractures O – missing tooth

OM – oral mass RC – previous root canal RD – retained deciduous tooth TR1 – lesion into enamel only TR2 – lesion into dentin TR3 – lesion into pulp TR4 (a/b/c) – extensive structural damage TR5 – crown lost TR – Type 1 TR – Type 2

RRT – retained root tip RTR – retained tooth root SN – supernumerary tooth ST – stomatitis (caudal/gingival/buccal) T/A/TLUX – tooth avulsion/luxation PD0 – no perio dx (maybe calculus) PD1 – gingivitis (no bone loss) PD2 – mild periodontitis (1 hp) is needed for power. If the delivery system is oxygen-, nitrogenor carbon dioxide–driven, use of sonic scalers can consume large volumes of gas, which might not be financially feasible. Daily lubrication is necessary for maintenance.

Ultrasonic Scaler Ultrasonic scalers are classified as magnetostrictive or piezoelectric. Magnetostrictive units use ferromagnetic stacks or ferrite rods to produce tip vibration. Ferromagnetic stacks are strips of laminated nickel attached with solder. When the operator wants to remove plaque and calculus from above the gingiva, the standard P-10 or beavertail insert is selected. When subgingival use is planned, magnetostrictive thin, long subgingival AfterFive (Hu-Friedy) and SLI Slimline (Dentsply Cavitron) inserts can be used safely. When an alternating electrical current is supplied to a wire coil in the magnetostrictive handpiece, a magnetic field is created around the stack or rod transducer, causing the tip to constrict and relax. This vibration energizes the water as it passes over the tip, producing a scouring effect to remove plaque, calculus, and stains. Bubbles are created which implode, affecting bacterial cell walls in the gingival sulcus. The water mist also cools the tip and irrigates debris. A piezoelectric scaler is activated by dimensional changes in crystals housed within the handpiece as electricity is passed over the surface of the crystals. The resultant vibration produces tip movement (fig. 6.21). When choosing an ultrasonic scaler, frequency, tip motion, and potential iatrogenic injury must be considered. Magnetostrictive advocates claim elliptical tip motion is most effective because it generates pathogendestroying cavitation bubbles 360 degrees around the tip. In contrast, the piezo design creates bubbles only at the two ends of the back-and-forth cycle. The sonic scaler does not produce cavitation bubbles.

Frequency Frequency is the number of times the scaler tip vibrates each second. A variety of frequencies are available within the three types of ultrasonic technologies. The higher frequencies (above 40,000 CPS) may provide greater efficiency. Ultrasonic scaling units are also available in manualtuning or auto-tuning models. Some researchers feel that

Equipment

161

compares the tip in use with an original. A loss of one millimeter of the tip equals a 25% loss of efficiency. A two millimeter loss of the tip equals a 50% loss in efficiency and the tip should be replaced. The magnetostrictive types of ultrasonic tips are changed with a pull-out/push-in action. O-rings are used in the handpiece and on the instrument to provide a tight fit and a seal to prevent water leakage. Piezocelectric scalers require a wrench to unscrew one tip and to replace it with another. Magnetostrictive inserts and piezoelectric tips should be cleaned and sterilized after each use. To clean, rinse thoroughly or immerse in an ultrasonic instrumentcleaning unit for 20 minutes. After removal, rinse the inserts with tap water and dry before packaging and sterilizing in a steam autoclave or gas sterilizer. Virtually all brands of magnetostrictive inserts of the same frequencies are interchangeable. Most 30 kHz units will operate only with 30 kHz inserts (a 25 kHz insert will not fit into the handle). Most piezoelectric scalers use tips designed specifically for each brand of scaler, which creates a problem if the manufacturer goes out of business.

Power Scaling Technique Follow these steps for the sonic/ultrasonic technique: 1.

Figure 6.21

Piezoelectric ultrasonic scaler.

better cavitation is achieved at low power settings if the scaler is slightly mistuned. Because auto-tuned scalers perfectly tune to the insert’s frequency, a manually tuned scaler would be preferred.

Tip Activity and Surfaces The activity of piezoelectric scalers is limited to the last 3 mm of the tip. Magnetostrictive metal stack tips are active at the last 4 mm of tip; the magnetostrictive ferrite rod scaler is active a full 12 mm of the tip. The most powerful surfaces of the magnetostrictive stack scaler tip are the underside and the top; the lateral sides are the least active. To prevent trauma to the tooth surface, only the lateral sides should be used against the tooth or within the gingival sulcus. The ferroceramic (ferrite) rod tip is equally active on all sides.

Tip Replacement Tip wear is critical to the efficiency of the scaling procedure. Tip wear can be evaluated using a chart which

Hold the handpiece lightly in a modified pen grasp; i.e., the scaler is held in the dominant hand with the pads of the index finger and thumb opposite to each other on the handle closest to the working end. The thumb and index finger are not touching, thereby creating a tripod effect with the middle finger placed along the shank of the instrument. This tripod effect balances the instrument in the operator ’s hand to provide stability and control by keeping the index finger and thumb separated. 2. The ultrasonic instrument should be grasped lightly, not tightly. It should feel balanced in the hand, with minimal pull from the handpiece cord. The handpiece, not the hands, must be allowed to do the work. The handpiece is balanced on the index or middle finger. A modified pen grasp is not as important in holding the ultrasonic or sonic scaler as it is with hand instruments. To decrease stress on the hand from the pull on the handpiece cord, the cord may be looped over the little finger (fig. 6.22). 3. Use eye, ear, and respiratory protection. 4. Hold the fulcrum or finger rest at a distance further from the tooth than with hand instruments, because the tips do not have cutting edges.

162

Feline Dentistry

Figure 6.22

Proper finger position.

Figure 6.23 Adjusted mist for ultrasonic scaling.

5. 6.

7.

8.

9.

10.

Adjust water spray to deliver a steady drip with a small mist halo (fig. 6.23). Apply light pressure to the tip working in a coronal-to-apical direction. The sound waves should do most of the work. Efficiency decreases with increased pressure. Pass the side of the working end over calculus and plaque in short, light vertical strokes. The scaler should not be used on a single tooth for too long to avoid iatrogenic damage. Heavy lateral pressure should be avoided. Keep the lateral surface working end in constant motion. Leaving it in one place too long increases the amount of tooth material removed and can cause thermal damage to the pulp. Never hold the tip perpendicular to the surface of the tooth. This will either etch or groove the surface. Specially designed subgingival periodontal tips may be used subgingivally. To avoid iatrogenic injury, decrease the power with subgingival use. After ultrasonic tooth cleaning is completed, use air from the air/water syringe to gently blow the gingival margin away from the tooth and examine the tooth surface for missed calculus.

High/Low Speed Delivery Systems Compressed air or gas can be used to power handpieces for polishing, tooth sectioning, endodontics, restoration, and oral surgery. The advantages over motorized systems lie in the capability of precise cutting at higher speed, and water cooling to prevent thermal damage to the pulp and surrounding bone. The compressor provides pressurized air for the airwater syringe and handpieces. Compressor size is important. The required capacity of the compressor is related to the number of operatories and handpieces used at the same time in the practice. The compressor must be large enough to maintain pressure of 30–40 psi at a flow rate of 3 cubic feet per minute. When the compressor is too small, it will run almost continuously during use and may overheat. If a sonic scaler or more than one station is used, a minimum of a 1 hp compressor is recommended. Compressors are either air- or oil-cooled. Air-cooling reduces the amount of contaminants (oil) in the line, but can be noisier and usually more expensive than oilcooling. Modified refrigerator oil–cooled compressors (“silent” compressors) are commonly used in smaller

Equipment

163

self-contained delivery systems. Unfortunately, when using an oil-cooled compressor, small particles of oil become mixed with the compressed air, which might contaminate tooth surfaces, interfering with restoration. Compressors for dental delivery systems are attached either to the unit (self-contained) or located remotely in a nearby cabinet, closet, attic or outside the clinic. The advantages of remote compressors include the following:

• • •

Less noise occurs in the operatory. Multiple stations may be attached to one compressor. Less storage is required in the immediate operatory area.

The storage or air tank holds air compressed by the compressor. This stored air is used to power the dental handpieces and air/water syringe. Air tanks come in many sizes. The larger the tank size, the less “work” the compressor needs to do. Pressure inside the air storage tank varies by manufacturer between 80–120 psi. When maintenance pressure is reached, the compressor turns off. When the tank pressure drops below 60 psi, the compressor turns on to refill the tank with compressed air. The assembly delivery system (control panel) contains the air/water supply syringe, tubing for the handpieces, pressure gauge(s), switches for turning water on and off, needle valve to adjust water flow and a switch to change from the high- to low-speed handpiece. The control panel may be part of a cart or mounted on the dental table (figs. 6.24 a,b). The foot pedal starts and stops the system and in some units controls handpiece speed.

Nitrogen-Powered Delivery Systems Some delivery systems use nitrogen to power handpieces. Nitrogen, an inert gas, can provide clean, oil-free power, which may extend the handpiece life. Because power is directly delivered from gas cylinders, compressors and air storage tanks are not necessary. There is no electrical requirement and no compressor noise. Additionally, nitrogen-driven delivery systems require less maintenance than air-driven units. The typical cost of nitrogen is less than US$1.50 per procedure. Nitrogen is not recommended to power air-driven sonic scalers because of the large volume of gas needed (figs. 6.25 a,b). A three-way air/water syringe is part of the delivery system. The syringe produces a stream of air, water or a spray, for rinsing debris from the teeth and drying as needed during dental procedures (fig. 6.26).

a

b Figure 6.24 a. Control panel, air/water syringe, handpieces, and ultrasonic scaler (Midmark). b. Nitair II (CBi).

Dental handpieces are precision-built mechanical devices designed for use with rotary instruments, such as burs, stones, wheels, and discs. Handpieces can be classified according to the revolutions per minute (RPM) or speed at which they operate. Handpieces that run under 100,000 RPM are classified as slow speeds. Models running at 20,000–100,000 RPM are classified as slowspeed type II mid speed. Low speed is a subcategory of slow speed. The handpieces commonly used in veterinary medicine run less than 20,000 RPM and are classified as slow-speed type III low speeds. The (s)low-speed (straight) handpiece commonly used in veterinary dentistry:

• • •

Rotates at 5,000–20,000 RPM Contains forward and reverse controls Operates with high torque

a

b Figure 6.25 a. Nitrogen-powered high-/low-speed delivery system (CBi). b. Portable delivery system.

164

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165

Figure 6.26 Three-way air/water syringe.

• • •

Generally does not use water (although some are water-equipped) Is used for polishing Is available as one- or multiple-section units

The one-section straight handpiece accepts cutting and polishing burs designated as handpiece (HP). An HP designation means that the cutting or polishing instrument has a long, straight shaft that inserts directly into the straight handpiece and is tightened by rotating the collar clockwise. A prophy head, right-angled handpiece or contra-angle may also attach to the one-section unit. The multiple-section, slow-speed handpiece is composed of a low E (European type) speed motor and a straight nose cone with a reduction gear to drive the prophy head, right-angled handpiece or contra-angle. Many units have a method of quickly connecting and disconnecting the motor and attachments. The contra-angle attaches to the slow-speed straight handpiece to form an extension with an angle greater than 90 degrees at the working end. Angulation provides better access to the posterior teeth. The contraangle’s main use is powering burs for finishing restorations and Gates Glidden drills for pulp chamber and root canal enlargement. The head of the contra-angle attachment contains either a latch or a friction type chuck, into which a dental bur or other rotary instrument is fitted. Latch-type contra-angles hold the end of the cutting instrument by mechanically grasping a small groove on the end of the instrument shaft. Right angle (RA) designates latch-type burs. Friction grip (FG) burs have short, smooth shafts without retention grooves.

The disposable plastic single-use prophy angle is preferred by the author because of reduced crosscontamination, lack of maintenance, ease of operation and low expense. The oscillating disposable prophy angle rotates 45 degrees and reverses. Advantages of the oscillating disposable prophy angle include decreased heat generated on the tooth surface and less lip hair caught in the polishing cup. High-speed handpieces are used when rapid and efficient cutting of the tooth and/or supporting bone is needed. High-speed handpieces are air-powered to 300,000–400,000 RPM. To avoid overheating, an irrigation spray is automatically delivered over the operative field. When choosing the handpiece style, a pediatric head gives the operator improved access in small animals. Some high-speed handpieces have a fiber-optic light built into the head. The light projects a beam from the head of the handpiece directly onto the bur and tooth. High-speed handpieces use friction grip (FG) burs. Attaching a bur to the high-speed handpiece is an easy procedure. The chuck is tightened by thumb control or built-in lever or by using a bur-inserting/-removal tool.

Rotary Cutting Instruments Rotary cutting dental instruments are used to:

•

Section multi-rooted teeth and/or remove part of the buccal alveolus, thus facilitating extraction.

166

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Feline Dentistry

Perform alveoloplasty to smooth out sharp projections. Provide access points for root canal therapy. Reduce crown height in crown reduction procedures. Remove part of the maxilla or mandible.

Burs are instruments placed into the dental handpiece. Burs consist of two parts: (1) The shaft fits into the handpiece. (2) The head is the cutting end.

Operative Bur Types Carbide steel burs (carbides) are used for cutting and are the most commonly used burs. Diamond points (diamonds) are burs covered with industrial diamond grit used for crown preparation, bone smoothing (alveoloplasty), scarification and shaping teeth (odontoplasty).

Three Types of Bur Shanks Straight handpiece burs have long straight shanks. In dental supply catalogs, they are abbreviated as SH or HP. Latch-type burs have notched shanks and are abbreviated as LA (latch-type angle) or RA (right-angled). Friction grip burs have smooth shanks, which are smaller in diameter than HP burs. They are used in highspeed handpieces. Friction grip burs are identified as FG, FGS (friction grip surgical) or FGSS (friction grip short shank used for tight areas and restorations). Surgical burs have longer (25 mm) shanks used to reach into deep recesses; restorative burs are shorter (20 mm).

Bur Shapes and Sizes Burs come in several sizes, represented by numbers. The lower the number in a series, the smaller the bur head. Round burs are most commonly used to open the pulp chamber in preparation for endodontic treatment, bone smoothing and root atomization. Their sizes range from 0.25–10. Inverted cone burs are wider at the tip with slightly rounded corners for added protection against chipping. Their sizes range from 33.5 to 37L (L indicates long). Inverted cones at one time were used to create undercut restoration sites for filling. Unfortunately, inverted cones may leave unsupported enamel at the restoration site.

Fissure burs have grooved heads and are useful for sectioning teeth and reducing crown height. The sides of straight fissure burs are parallel. The sides of taper fissure burs converge toward the tip. Fissure burs may also contain cross-cuts along the blades (called cross-cut fissure burs), which act like saw teeth to allow additional cutting ability. The size of straight fissure burs ranges from 56–58L, that of cross-cut straight fissure burs from 556–558L and that of taper fissure burs from 699–703. Diamond burs have industrial diamond grit embedded into the working surfaces. Diamonds are used in many places that carbides the tooth to receive are, and especially in restorative dentistry to prepare the tooth to receive prosthodontic crowns, and to help finish composite restorations. Trimming and finishing burs are designed for completing restorations, odontoplasty and alveoloplasty. The more flutes on a finishing bur, the finer will be the finish (a 30-fluted bur, also known as a fine finishing bur, produces a smoother finish than does a 12-fluted bur). Stones are used for polishing and finishing restorations. Stones are mounted on a mandrel (mounting device), which is inserted into the handpiece. Stones are identified by color. White stone burs are commonly used in veterinary dentistry to finish composite restorations or to smooth minor enamel defects. Green stones are used to finish amalgam and smooth enamel. Gray stones, made of carborundum and rubber, are used for polishing fabricated crowns. Finishing discs are used to shape and smooth restorations. They are available in various grades of abrasiveness, from coarse to superfine and are used sequentially from coarse (to shape restorations) to fine grade (to smooth surfaces). The finest-grade disk is used with a paste.

Bur Care Burs are surgical cutting instruments and should be cleaned and sterilized before each use. To remove debris lodged in the bur head, the bur is removed from the handpiece then rinsed, brushed free of debris with a nylon or wire bur brush (or pencil eraser) and soaked in a cold sterile solution for 24 hours.

Equipment Maintenance Dental handpieces are precision instruments and must be maintained properly to ensure optimal operation and maximum life. The veterinarian or technician should check with the manufacturer ’s instructions for specific care.

Equipment

A generic lubrication/sterilization process consists of these steps: 1.

2. 3. 4.

5. 6. 7.

At the end of each procedure, scrub the handpiece with gauze, a sponge, or a brush and cleaning solution to remove debris. Following the manufacturer ’s instructions, rinse the handpiece without immersion. Dry the handpiece with gauze, paper towel, or air from the air/water syringe. For handpieces requiring lubrication, add three drops of lubricant to the smaller of the two large holes (drive air tube) at the connection area. Note: Some handpieces are lubrication-free and will be destroyed if lubricated; check manufacturer ’s instructions. Briefly power the handpiece with the bur inserted to remove excess lubricant. Place the handpiece in an autoclavable envelope. Sterilize the handpiece in the autoclave.

Replacing the High-Speed Turbine The turbine is secured in the high-speed handpiece head by a screwed faceplate. After the faceplate is unscrewed using the manufacturer-supplied tool, the turbine can be easily replaced. To clean and lubricate the low-speed handpiece and attachments, use the following steps: 1. Place the working end of the handpiece into a small bottle of handpiece-cleaning solvent. 2. Power the handpiece backward and forward for one minute. 3. Remove the handpiece from the cleaner and wipe dry. 4. Periodically, disassemble the handpiece, using the special wrench furnished by the manufacturer. 5. Following the manufacturer ’s instructions, place one drop of liquid lubricant on the neck of the head, one drop on each gear of the gear and shaft assembly, and three drops into the back end of the angle. Alternatively, place heavy lubricant (petroleum jelly) on the gears of the handpiece before reassembly.

Compressor Maintenance Oil-cooled compressors are equipped with a dipstick or view port to monitor the oil level. The owner ’s manual should be checked for the recommended replacement oil if needed. Some compressors are “oil free” and do not require oil maintenance.

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Condensation in the air storage tank accumulates with each use. The accumulated fluid should be drained weekly to monthly depending on use and ambient humidity.

Infection Control Disinfection is the process of destroying microbial life by placing instruments in a solution (example: Cidex) for a specified period. Chemical disinfection does not eliminate all viruses and spores. Sterilization kills all microorganisms. The autoclave is a steam chamber for sterilizing instruments. During the sterilization cycle, distilled water flows into the chamber and is heated to create steam. Because the chamber is sealed, pressure increases to approximately 15 pounds per square inch. The increase in pressure causes the heat of the steam to rise to approximately 250 °F. When the instruments are exposed to this high pressure/steam temperature for 15 minutes or more, sterilization occurs. Dental instruments used in the mouth should be sterile. After cleaning, instruments can be placed in an autoclavable see-through sleeve and sterilized. Patient and operator infection control requires the following: An individual set of sterilized instruments should be used on each patient. Human dentists have developed aggressive infection control procedures in response to spreading HIV and hepatitis among patients and staff. Many of these protocols can be adopted in veterinary hospitals for similar reasons. Viral and bacterial particles may become lodged in the paste remaining on the head of the prophy angle and transmitted to the next patient even if the prophy cup is changed. Disposable prophy angles or autoclaved metal angles are recommended for all feline patients to prevent spread of feline leukemia virus and feline immunodeficiency virus. Polishing paste is available in individual cups or in bulk form in a supply container. When using the bulk container, the paste should be applied with a new and clean tongue depressor to avoid contaminating the container. A mask, gloves, and ear and eye protection should be worn when performing dental care. The oral cavity should be rinsed with a 0.12% chlorhexidine solution before oral procedures to reduce the number of bacteria that could enter blood vessels of the patient (bacteremia) or become aerosolized during power scaling. The patient’s head should be angled downward to promote drainage. High-speed delivery system fluid lines can develop a biofilm of potentially harmful viruses and bacteria. Chlorhexidine can be used to flush the fluid lines, thus decreasing the viral and bacterial load.

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Further Reading Deeprose J. Operator safety and health considerations. In: Tutt C, Deeprose J, Crossley D (eds). BSAVA Manual of Canine and Feline Dentistry, 3rd ed. BSAVA, Gloucester, 2007; 56–66. Gorrel C, Penman S. Dental equipment. In: Crossley DA, Penman S (eds). Manual of Small Animal Dentistry, 2nd ed. BSAVA, Cheltenham, 1995; 12–18. Harvey CE, Emily PP. Small animal dental equipment and materials, Small Animal Dentistry, Mosby, St. Louis, 1993; 378–400. Holmstrom SE, Frost Fitch P, Eisner ER. Dental equipment and care, Veterinary Dental Techniques for the Small Animal Practitioner, 3rd ed. Saunders, Philadelphia, 2004; 39–129.

Lipscomb V, Reiter AM. Surgical materials and instrumentation. In: Brockman DJ, Holt DE (eds). BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery. BSAVA, Gloucester, 2005; 16–24. Robinson J. Dental instrumentation and equipment. In: Tutt C, Deeprose J, Crossley D (eds). BSAVA Manual of Canine and Feline Dentistry, 3rd ed. BSAVA, Gloucester, 2007; 67–76. Wiggs RB, Lobprise HB. Dental equipment, basic materials and supplies, Veterinary Dentistry—Principles and Practice, Lippincott-Raven, Philadelphia, 1997; 1–54.

Chapter 7

Anesthesia

General anesthesia is necessary for the oral assessment, treatment, and prevention visits. The American Veterinary Dental College (AVDC) created a position statement (below) regarding the need for general anesthesia to provide companion animal dental diagnostics and therapy (fig. 7.1).

Non-Professional Dental Scaling (NPDS) In the United States and Canada, only licensed veterinarians can practice veterinary medicine. Veterinary medicine includes veterinary surgery, medicine, and dentistry. Anyone providing dental services other than a licensed veterinarian, or a supervised and trained veterinary technician, is practicing veterinary medicine without a license and shall be subject to criminal charges. Although the term “Anesthesia-Free Dentistry” has been used in this context, AVDC prefers to use the more accurate term Non-Professional Dental Scaling (NPDS) to describe this combination. This position statement addresses dental scaling procedures performed on pets without anesthesia, often by individuals untrained in veterinary dental techniques. Owners of pets naturally are concerned when anesthesia is required for their pet. However, performing NPDS on an unanesthetized pet is inappropriate for the following reasons: 1.

2.

Dental tartar is firmly adhered to the surface of the teeth. Scaling to remove tartar is accomplished using ultrasonic and sonic power scalers, plus hand instruments that must have a sharp working edge to be used effectively. Even slight head movement by the patient could result in injury to the oral tissues of the patient, and the operator may be bitten when the patient reacts. Professional dental scaling includes scaling the surfaces of the teeth both above and below the gingival margin (gum line), followed by dental polishing. The most critical part of a dental scaling procedure is scaling the tooth surfaces that are within the gingival pocket (the subgin-

3.

4.

gival space between the gum and the root), where periodontal disease is active. Because the patient cooperates, dental scaling of human teeth performed by a professional trained in the procedures can be completed successfully without anesthesia. However, access to the subgingival area of every tooth is impossible in an unanesthetized canine or feline patient. Removal of dental tartar on the visible surfaces of the teeth has little effect on a pet’s health and provides a false sense of accomplishment. The effect is purely cosmetic. Inhalation anesthesia using a cuffed endotracheal tube provides three important advantages—the cooperation of the patient with a procedure it does not understand, elimination of pain resulting from examination and treatment of affected dental tissues during the procedure, and protection of the airway and lungs from accidental aspiration. A complete oral examination, which is an important part of a professional dental scaling procedure, is not possible in an unanesthetized patient. The surfaces of the teeth facing the tongue cannot be examined, and areas of disease and discomfort are likely to be missed.

Safe use of an anesthetic or sedative in a dog or cat requires evaluation of the general health and size of the patient to determine the appropriate drug and dose, and continual monitoring of the patient. Veterinarians are trained in all of these procedures. Prescribing or administering anesthetic or sedative drugs by a non-veterinarian can be very dangerous, and is illegal. Although anesthesia will never be 100% risk-free, modern anesthetic and patient evaluation techniques used in veterinary hospitals minimize the risks, and millions of dental scaling procedures are safely performed each year in veterinary hospitals. To minimize the need for professional dental scaling procedures and to maintain optimal oral health, the AVDC recommends daily dental home care from an early age. This should include brushing or use of other effective techniques to retard accumulation of dental plaque, such as dental diets and chew 169

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a

Figure 7.1 Patient anesthetized, temperature control assist Bair Hugger®, Cardell® monitor, Matrix® anesthetic unit attached to adjustable height hydraulic table (Canis Major, Midmark).

b Figure 7.2 a. ECG evaluation software (DVM Solutions). b. Preanesthesia blood pressure evaluation (DVM Solutions).

materials. This, combined with periodic examination of the patient by a veterinarian and with dental scaling under anesthesia when indicated, will optimize life-long oral health for dogs and cats. For general information on performance of dental procedures on veterinary patients, please read the AVDC Position Statement on Veterinary Dental Healthcare Providers, which is available on the AVDC website (www.AVDC.org). For information on effective oral hygiene products for dogs and cats, visit the Veterinary Oral Health Council website (www. VOHC.org).

Anesthesia protocols vary by patient age, condition, morbidity factors, and length and type of procedure. Local anesthetics are used on all dental surgical cases where tissue is incised (see Table 7.1 at end of chapter).

Preanesthetic Evaluation

Premedication

All anesthetic patients require proper preanesthetic evaluation including a detailed history, physical examination, and laboratory testing. Patients with preexisting medical conditions may need further evaluation to modify the anesthetic protocol (figs. 7.2 a, b). Hyperthyroidism, diabetes mellitus, and chronic renal disease are common feline diseases requiring special anesthetic attention. Generally, unless the patient is in pain, conditions yielding abnormal test values should be corrected before dental care is rendered.

An intravenous catheter is placed and fluids are administered in all patients undergoing anesthesia. Premedication for healthy cats may include hydromorphone 0.1 mg/kg IM or SC or butorphanol 0.2 mg/ kg IM or SC combined with dexmedetomidine 0.0025 to 0.01 mg/kg IM (fig. 7.3). As cats become more debilitated or aged, butorphanol 0.2 mg/kg IM or SC or hydromorphone 0.05–0.2 mg/kg IM or SC with 0.2–0.4 mg/kg midazolam IM can be considered.

Anesthesia Protocols

Anesthesia

171

must be considered when anesthetizing older or ill patients.

Etomidate

Figure 7.3

Preanesthetic medication.

For fractious cats presenting without feline hypertrophic cardiomyopathy, a combined dose of medetomidine HCl 0.01–0.02 mg/kg, plus buprenorphine 0.01–0.02 mg/kg, ketamine HCl 1–3 mg/kg, and butorphanol tartarate 0.1 mg/kg are mixed in one syringe and administered IM; for fractious cats with feline hypertrophic cardiomyopathy, low-volume medetomidine (0.005 mg/kg) plus butorphanol tartarate 0.1–0.2 mg/kg plus or minus midazolam HCl 0.2 mg/kg may be administered. All patients should be individually assessed and a patient-specific anesthetic premedication protocol developed, as the above are simply examples of typical premedication protocols.

Etomidate (0.5–1.5 mg/kg IV) is the induction drug of choice for patients that have cardiovascular disease or arrhythmias (except A-V dissociation) because cardiac output and blood flow to the kidneys are maintained. However, there have been reports of hemolysis in cats after etomidate injection. A premedicant (e.g., butorphanol IV, SC, IM; diazepam; or midazolam IV) should be administered prior to etomidate administration.

Pain Control Anesthesia protocols linked to pain control (in addition to local anesthesia) include the following:

•

•

Expected mild to moderate pain–-buprenorphine 0.01–0.03 IM, IV sublingually mg/kg plus midazolam 0.2 mg/kg, plus 0.0005–0.075 mg/kg dexmedetomidine (0.0025–0.005 μg/kg). Expected moderate- to high-level pain–-hydromorphone 0.1 mg/kg plus midazolam 0.2 mg/kg, plus dexmedetomidine 0.0005–0.075 mg/kg (0.5–7.5 μg/ kg).

Induction There are many feline anesthesia protocols for the healthy young to middle-aged cat.

Chamber or Mask Induction Chamber or mask induction should be avoided due to catecholamine release during the excitement phase from the struggle against restraint or as a reaction to the pungent odor of the inhalant anesthetic agent.

Propofol Propofol (2,6-diisoproylphenol) (3–4 mg/kg IV; 3 mg/kg if opioid is given as a premedicant), with half of the dose given as a slow bolus over 40–60 seconds the rest to effect, is a nonbarbiturate hypnotic. Slightly higher doses are required for cats than dogs, and recoveries are longer in cats than dogs when the infusion lasts more than 30 minutes due to decrease in glucuronide conjugation. Propofol provides no analgesia in the cat. Propofol is a direct myocardial depressant resulting in both venous and arterial relaxation, thus creating hypotension. This hypotension is well recognized clinically and

Intubation All cats placed under anesthesia for oral assessment and treatment must be intubated and the airway secured with an inflatable cuff. Topical lidocaine may be applied to the laryngeal mucosa to facilitate passage of the endotracheal tube. The endotracheal tube should be secured before the cuff is inflated. The cuff should be inflated to a light seal. Overinflation of the endotracheal cuff must be avoided. Subcutaneous emphysema and pneumothorax have occurred during or after anesthesia in cats anesthetized for dental care. It is critical that anytime the head is moved from side to side during assessment or dental treatment, the endotracheal tube be disconnected from the anesthesia machine and reconnected after the new position is reached (figs. 7.4 a, b).

Maintenance Anesthesia is generally maintained with isoflurane or sevoflurane and oxygen. Little isoflurane or sevoflurane

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a a

b Figure 7.5 a. Hot Dog® patient warmer. b. Bair Hugger® used below the patient.

to support body temperature. It is much easier to prevent hypothermia than to treat it (figs. 7.5 a, b). b Figure 7.4 a. Lateral thoracic radiograph before anesthesia. b. Pneumothorax, pneumomediastinum, and pneumoabdomen secondary to endotracheal tube–induced tracheal tear.

is metabolized. The insolubility of the inhalants allows for a rapid induction and recovery. Patient body temperature control is necessary. Long anesthetic procedures coupled with the frequent use of water and the ambient room temperature may create hypothermia. In a risk determination study of 138 anesthetized cats, 71 (51%) had rectal body temperatures ≤35 °C (95 °F); the lowest recorded temperature was 28.8 °C (83.8 °F). Prolonged anesthesia dramatically increased the risk of hypothermia. In addition to the increased infection rate seen in hypothermic patients, there is increased risk of fatal ventricular arrhythmias in patients with body temperatures 50%) periodontal support loss

Extraction of affected teeth

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Figure 8.2 Adjusted ultrasonic spray. Figure 8.1 Anesthetized cat for oral ATP visit.

shock waves (cavitation) that disrupt the bacterial cell wall and lead to bacterial cell death. Additionally, acoustic streaming occurs when a continuous torrent of water produces tremendous pressure within the confined space of the periodontal pocket, resulting in a decreased number of bacteria. Gram-negative, motile rods in particular are sensitive to acoustic streaming because of their thin cell walls.

Operator and Patient Protection To protect from bacterial aerosols and other effects of ultrasonic scaling, the operator should wear a surgical mask, ear protection, gloves, glasses, and/or a face shield, surgical cap, and smock. The anesthetized patient should have artificial tears ophthalmic preparation applied to the corneal surfaces to protect from drying and irritation. When in lateral recumbency, the cat’s head should be cushioned to protect the eye closer to the table surface from abrasion and to raise it off the table to prevent water contamination. The upper eye should be draped to protect it from fomites and from prolonged exposure to the procedure light (fig. 8.1). The mouth is rinsed with 0.12% chlorhexidine gluconate or acetate before the scaling begins.

Supragingival (Above the Gum Line) Scaling 1.

Hold the ultrasonic handpiece lightly at a distance further from the tooth than with hand instruments.

Figure 8.3

Proper position of ultrasonic scaler against crown surface.

2. Adjust water spray to deliver a steady drip with a small mist halo (fig. 8.2). 3. Apply the side of the scaler lightly to the crown in a coronal-to-apical direction. The sound waves should do most of the work. Efficiency decreases with increased pressure. 4. Keep the lateral surface working end in constant motion. Leaving it in one place too long increases the amount of potential heat or mechanical damage to the tooth or gingiva. To prevent enamel damage, never hold the tip perpendicular to the surface of the tooth (fig. 8.3).

Treatment of Periodontal Disease

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Subgingival (Below the Gum Line) Scaling Calculus, coated with bacteria, left on the root surface contributes to the progression of periodontal disease. If subgingival calculus removal is not performed, the teeth have not been adequately cleaned. Subgingival root cleaning can be accomplished with curettes or special ultrasonic, thin, periodontal tips manufactured specifically for root surface use. When there is enough space between the marginal gingiva and root, a fine curette can be inserted with the face of the blade flush against the tooth. When the instrument reaches the bottom of the pocket, the working angulation of the instrument–-usually anywhere between 45 and 90 degrees–-is established. The instrument is then pushed against the tooth and pulled coronally. This process is repeated until all subgingival calculus is removed (fig. 8.4). To avoid iatrogenic injury when using the ultrasonic scaler with periodontal tips for removal of plaque and calculus, decrease the power and increase the amount of water irrigation. After ultrasonic tooth cleaning is completed, use air from the air/water syringe to gently blow the gingival margin away from the tooth, and examine the tooth surface for missed plaque and calculus. Water from the air/water syringe is used to lavage unattached debris from the sulcus or pocket after cleaning.

Tooth Polishing Polishing smoothes minor enamel defects and removes some of the plaque missed during previous steps. Regardless of how careful scaling and curettage are performed, minor defects (microetches) of the tooth surface occur. Polishing teeth decreases the surface area of enamel and cementum microetches, retarding plaque reestablishment. Tooth polishing can be accomplished by applying polishing paste on the prophylaxis cup attached to a slowspeed handpiece. Cross-contamination can be avoided between different cats by using disposable polishing angles and individual paste cups. When polishing, light pressure is applied to each tooth until the cup edge flares. Care must be taken not to hold the cup on one spot for more than a few seconds to prevent overheating and subsequent damage to the pulp. Cementum and dentin are softer than enamel. When exposed from gingival recession, they should be polished for a few seconds only to avoid further wear.

Figure 8.4 Thin curette (NVO Cislak).

Air polishing uses sodium bicarbonate to “sandblast” the tooth surface smooth in addition to or as a replacement for conventional polishing. The small size of cat teeth generally precludes air polishing due to potential iatrogenic damage to the gingiva.

Fluoride Application Potential fluoride advantages in veterinary dentistry include reduction in tooth sensitivity from exposed dentinal tubules, decreased plaque accumulation, increased enamel resistance to acid demineralization, and a clientpleasing cherrylike aroma after application (FluraFom Virbac Products). Fluoride can be applied while the cat is anesthetized, after the teeth are cleaned and polished and before the plaque barrier gel OraVet® is applied. Both the gel and foam have a pH of 3.0, which may cause gastric irritation and nausea if swallowed; it is therefore administered in the clinic while the patient is still intubated and has a barrier in the oropharynx. Fluoride is deposited in the gingival sulcus with a cotton-tipped applicator, a soft toothbrush, or a foam

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a

b

Figure 8.5

Fluoride.

applicator and is allowed to remain in contact with the tooth surface for three minutes. When using fluoride foam, approximately one-half inch of the foam is rubbed over the teeth. After three minutes, the foam is removed with suction or with a dry gauze sponge. Irrigation is not used after fluoride application (fig. 8.5).

Barrier GEL c

OraVet® (Merial) can be applied to the crown and root to provide a barrier against plaque attachment. The waxy gel is applied with an applicator device on dried teeth at the gingiva/tooth interface before the cat is awakened from anesthesia (figs. 8.6 a, b, c). The at-home product should be applied weekly to help prevent plaque accumulation. In a double-blind study on OraVet®, those cats treated with the professional application during the oral assess-

Figure 8.6 a. OraVet® professional application kit. b. Applying OraVet® to the tooth surface during anesthesia. c. Applying OraVet® supra- and subgingivally with a polishing cup.

ment, treatment, and prevention visit, followed by weekly application, showed significant decrease in the amount of plaque accumulation compared with controls during the fifty-six-day evaluation period.

Treatment of Periodontal Disease

Antibiotics Bacterial load in the mouth and bacteremia can be significantly decreased when the oral cavity is rinsed with 0.12% chlorhexidine gluconate after general anesthesia is induced and before tooth cleaning or oral surgery. Antibiotics are not indicated in most patients with periodontal disease. The goal of periodontal therapy is to remove the cause of inflammation–-plaque, calculus, or periodontal pockets. Treating the infection with antibiotics but without mechanical debridement will at best result in a temporary improvement and at worst cause the development of resistant pathogens. In stage 3 and 4 periodontal disease, antibiotic use is controversial but may be indicated. Choosing the appropriate antibiotic can be challenging. One in-vitro study found either amoxicillin-clavulanic acid or cefadroxil most effective against gram positive and negative aerobic bacteria in cats with gingivitis. For anaerobic bacteria, amoxicillin-clavulanic acid or clindamycin were most effective. Pulse therapy is the use of periodic (i.e., first five days of every month) oral antibiotic administration to help control the bacterial load. However, this is only rarely recommended as an adjunct in cases where periodontal pocket disease has been treated and the client can provide daily home care. Pulse therapy is not indicated in cases where periodontal disease exists, anesthesia is not performed due to client or practitioner concerns, or as a substitute for home care.

Bone Grafting Bone grafts are used to preserve or restore the alveolar height in deep, narrow, three-walled infrabony pockets, such as defects on the palatal side of canine teeth, that do not extend into the nasal cavity. The goals of bone grafting are to restore normal bony architecture, rebuild the periodontal ligament and soft tissue, and prevent further periodontal pocket formation. Many materials have been used for cat bone grafts, including autogenous bone, alloplasts, and synthetic bioactive ceramic such as Bioglass® (Consil®, Consil Putty Nutramax Laboratories), which develops a direct bond to tissue and becomes osteoconductive when implanted into an osseous defect. The ceramic is surrounded by and incorporated into the new bone within weeks.

2.

3.

4.

5.

1.

If chlorhexidine is used as an irrigant during surgery, rinse it off thoroughly with lactated Ringer ’s solu-

tion. Chlorhexidine can devitalize periodontal ligament cells and interfere with attachment. Create an access flap with interdental and sulcular incisions. Plane the root smooth with a curette and remove excess granulation tissue. Add four to six drops of the patient’s blood, sterile water, or saline to 0.5 mL of the graft material in a dappen dish. Mix the liquid and granules (e.g., Consil®) in the dappen dish with a spatula for ten seconds to achieve the consistency of firm wet sand and apply it into the defect area. Alternatively, carry the granules to the defect and mix with the patient’s blood. In two to three minutes, a chemical change occurs within the granules that initiates the process of bone regeneration. Consil Putty® can also be applied into the defect. Suture the access flap without tension.

Postoperative care includes pain control and antimicrobial medication. The cat is fed a soft diet for several days. Gentle brushing can begin one week after surgery. The surgical site is reexamined every two weeks until clinical healing is confirmed. The area is radiographed in four months.

Technique for the Palatal Periodontal Pocket Palatal pocket therapy is indicated in cases where there is >25% attachment loss on the palatal aspect of one or both maxillary canine teeth and the periodontal probe does not yet enter the nasal cavity (figs. 8.7 a, b). When deep pockets are diagnosed, pocket therapy should be performed or the tooth extracted and the defect closed. If untreated, the pocket might progress until it penetrates the nasal cavity, creating an oronasal fistula. 1.

2. 3.

4.

General Technique

185

5.

Make 2–4 mm mesial and distal incisions to the bone at 20-degree angles palatally from the affected tooth (figs. 8.7 c, d). Use a Molt or Freer periosteal elevator to gently raise a full-thickness flap (figs. 8.7 e, f). Use a thin curette to clean accessible granulation tissue, calculus, and plaque between the root and alveolus (figs. 8.7 g, h). Carry bone-grafting particles into the cleaned defect (fig. 8.7 i). Oppose the flap snugly against the tooth with 4-0 absorbable suture on an atraumatic needle (fig. 8.7j).

a

b

c

Figure 8.7 a. Maxillary canine teeth palatal bleeding after dental scaling. b. 7-mm palatal periodontal pocket. c. Palatal incision. d. Buccal incision. e. and f. Freer elevator used to move palatal tissue caudally exposing subgingival calculus. g. Curette used to remove plaque and calculus. h. Prepared palatal defect. i. Consil® application into the defect. j. Sutured palatal defect.

186

f

d

g

e Figure 8.7 Continued

187

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Feline Dentistry

i h

j Figure 8.7 Continued

Alveolar Bone Expansion Maxillary and/or mandibular canine teeth affected by chronic alveolar osteitis clinically present with unilateral or bilateral thickening (bulging) of the buccal alveolar bone (fig. 8.8a). Oral probing and radiographic examination usually reveal stages 2 to 4 periodontal disease (fig. 8.8b). Teeth

affected with stage 4 disease should be surgically extracted after the bulging alveolus is exposed. The bulge is flattened via alveoloplasty before flap closure (fig. 8.8 c–q). In cases where the maxillary canine tooth has been extracted, the mandibular canine tooth crown may now interfere with the lip, requiring extraction or crown reduction and restoration (fig. 8.9; see chap. 9, pp. 209 for technique).

a

d

b

e

c

Figure 8.8 a. Bilateral maxillary canine alveolar osteitis. b. Left maxillary canine 12-mm probing depth. c. Incision caudal to the affected left maxillary canine. d. Molt elevator used to separate attached gingiva from underlying periosteum. e. Molt elevator used rostrally. f. Reflected attached gingiva. g. Alveolar bone expansion site exposed. h. Removal of the coronal alveolus to aid extraction. i–k. Wing-tipped elevator used to create mobility. l. Delivery of tooth from the alveolus. m and n. After additional alveoloplasty, the periosteum is partially excised to free up gingiva for tension-free closure. o. Before suturing, gingiva is opposed over defect. p. First suture at most coronal point. q. Defect sutured.

189

h

f

g Figure 8.8 Continued

190

i

j

l

m

k Figure 8.8 Continued

191

n p

o

Figure 8.8 Continued

192

q

Treatment of Periodontal Disease

Figure 8.9

193

Mandibular canine lip impingement secondary to extraction of the ipsalateral maxillary canine tooth.

Multiple Tooth Extractions for Advanced Periodontal Disease Often the best approach to care for the cat with advanced periodontal disease is multiple extractions. In most cases the surgical area heals without incident and the cat rapidly returns to normal function (figs. 8.10 a–f).

Gingival Enlargement Benign proliferation of the gingiva is termed gingival hyperplasia. Gingival hyperplasia, rare in the cat, results in increased pocket depths, caused by augmented gingival height, not attachment loss. The resultant “pseudo pocket” can accumulate plaque and, if untreated, may progress to attachment loss. Gingival hyperplasia is treated by gingivectomy and strict home care to help prevent recurrence. At least two millimeters of attached gingiva should remain after gingivectomy.

a e

b

c f

d

194

Figure 8.10 a. Stages 3 and 4 periodontal disease and tooth resorption. b. Flap exposure. c. Partial removal of the coronal buccal alveolus and sectioning of the teeth before extraction. d. Extraction of the mandibular third premolar. e. Separation of the gingiva from the lingual side of the mandible to allow smoothing of the sharp alveoli (alveoloplasty). f. Alveoloplasty.

Treatment of Periodontal Disease

Further Reading Beebe DE, Gengler WR. Osseous surgery to augment treatment of chronic periodontitis of canine teeth in a cat. J Vet Dent. 2007; 24: 30–38. Harvey CE. Management of periodontal disease: understanding the options. Vet Clin North Am Small Anim Pract 2005; 31: 819–836. Harvey CE, Emily PP. Periodontal disease. Small Animal Dentistry. Mosby-Year Book, St. Louis, 1993; 89–144. Harvey CE, Thornsberry C, Miller BR, Shofer FS. Antimicrobial susceptibility of subgingival bacterial flora in cats with gingivitis. J Vet Dent 1995; 12: 157–160.

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Holmstrom SE, Frost Fitch P, Eisner ER. Dental prophylaxis and periodontal disease stages, Veterinary Dental Techniques for the Small Animal Practitioner, 3rd ed. Saunders, Philadelphia, 2004; 175–232. Holmstrom SE, Frost Fitch P, Eisner ER. Periodontal therapy and surgery, Veterinary Dental Techniques for the Small Animal Practitioner, 3rd ed. Saunders, Philadelphia, 2004; 233–290. Norris JM, Love DN. In vitro antimicrobial susceptibilities of three Porphyromonas spp and in vivo responses in the oral cavity of cats to selected antimicrobial agents. Aust Vet J 2000; 78: 533–537.

Chapter 9

Treatment of Endodontic Disease

Endodontic treatment or extraction is required when the pulp is exposed by trauma. When exposed to the oral environment, pulpal contents undergo irreversible degenerative inflammation resulting in necrosis. There are many clinical presentations for a tooth affected with endodontic pathology. The crown may or may not be fractured. If fractured, the pulp may or may not be visible. Pulpitis may result if there is no obvious fracture–-it may only be visible clinically as a discolored tooth. In advanced cases, fistulous tracts apical to the mucogingival junction can be observed. A majority of cats presented with fractured teeth do not show any signs of discomfort, even though animals experience pain similar to humans. Cats frequently do not show overt signs of pain because they would be regarded as weak. When the pulp necroses, the pain decreases unless periapical lesions form. The mere fact that a cat does not appear to be in pain does not eliminate the need to treat the fractured tooth. Secondary signs related to fractured teeth include:

• • • • • • • • • • •

Chewing on one side Dropping food from the mouth when eating Excessive drooling Grinding of teeth Pawing at the mouth Facial edema Fistulous tract below the eye or under the mandible Regional lymph node enlargement Shying away when the face is petted Refusing to eat hard food Refusing to chew on hard treats or toys

When presented with a tooth that is fractured and has pulp exposure (complicated tooth fracture), the practitioner has two choices: 1. 2.

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Extract the tooth. Perform endodontic therapy, which usually allows the tooth to be saved and returned to function. Endodontic therapy is less invasive than open extraction.

Specific endodontic therapy depends on the severity of damage to the tooth structure, periapical and periodontal pathology, the functional significance of the tooth, equipment available, and the confidence and ability of the veterinarian to perform endodontic therapy (or refer the case).

Severity of Damage to the Tooth Structure In cats, the pulp lies closer to the enamel compared with dogs. Some fractures are limited to enamel and require little or no therapy; others involve dentin and might not require endodontic care; still others expose enamel, dentin, and pulp, and require endodontic care or extraction. Due to the proximity of the pulp chamber to the coronal enamel, even moderate dentin involvement without obvious pulp exposure should be treated. The ultimate goal of endodontic care is to return the tooth to function if possible, and if not possible, to extract the tooth to prevent further pain. When pathology secondary to pulp necrosis and/or concomitant disease renders the tooth nonfunctional, extraction is the treatment of choice (figs. 9.1a, b, c; 9.2 a–e).

Degree of Periapical and Periodontal Changes Tooth support is critical to long-term success of endodontic treatment. If marked periodontal disease is present before therapy, success will be unlikely unless epic measures are taken and strict home care is provided (figs. 9.3 a, b, c).

Functional Significance of the Tooth Although endodontic care can be performed on any tooth, in the cat, the canines and maxillary fourth premolars generally are the only teeth where endodontic

a

c

b

Figure 9.1 a. Complicated crown fracture of the right maxillary canine. b. Radiograph revealing periapical lucency. c. Root canal therapy four months postoperatively showing partial resolution of periapical lucency (prognosis guarded).

197

a

c

b

d Figure 9.2 a. Complicated crown fracture of the left maxillary canine in a four-year-old cat. b. Radiograph revealing an enlarged pulp cavity and an open apex indicating fracture occurred when the cat was between six and nine months old, halting tooth maturation. c. Extracted tooth cut along its long axis. d. Complicated crown fracture. e. External and possible internal tooth resorption present in addition to the fracture.

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e

Figure 9.2 Continued

a

c

b

Figure 9.3 a. Crown-root fracture, mandibular fourth premolar. b. Radiograph revealing enlarged root canal and periodontal disease of the fractured crownroot segment. c. Postextraction radiograph.

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therapy would be considered due to the surgical discomfort that accompanies extraction.

Owner’s Expectation and Desires Before commencing endodontic therapy, the owner must be made aware of the prognosis, fees involved, and follow-up care required.

is so beneficial in the healing response in other body areas creates swelling leading to pulpal death and necrosis due to the nonelastic and hard surroundings of the pulp cavity (fig. 9.4). Pulpitis is uncommonly associated with tooth resorption in the cat, for which extraction is the treatment of choice. Root canal therapy can be performed on a discolored tooth without radiographic signs of resorption, with a guarded prognosis. If there are radiographic signs of resorption, root canal therapy will not halt the progression of resorption.

Clinician’s Availability and Skill If the client refuses advanced endodontic therapy, the veterinarian is unable to perform endodontics, or referral is not available, extraction may be the only option for care of the fractured tooth with pulpal exposure.

Endodontic Care Based on Presentation Pulpitis Occasionally, teeth can be traumatized by blunt trauma, hyperthermia from ultrasonic scaling, and/or overly aggressive polishing. The resulting inflammation may be sufficient to cause vascular damage, hemorrhage, and pulpal swelling. The pulp is contained within a solid unyielding chamber with limited blood supply and no collateral support; thus, the inflammatory process that

Figure 9.4

Discolored tooth consistent with pulpal hemorrhage.

Uncomplicated Tooth Fractures Uncomplicated fractures are classified into enamel, crown, and crown/root fractures. An enamel fracture occurs when there is loss of crown substance confined to the enamel (fig. 9.5). The dentin or pulp is not exposed. Intraoral radiographs should be exposed and examined as a baseline and to check for additional root fracture. The tooth should be radiographed six and twelve months later for evidence of periapical pathology. Treatment of enamel fractures entails smoothing and contouring the surface with a white stone or fine

Figure 9.5

Enamel fracture illustration.

Treatment of Endodontic Disease

diamond bur on a water-cooled, high-speed handpiece to remove sharp edges, which could cause trauma to the lips and tongue. Light-cured dentin bonding resin material can be placed at the fracture site according to the manufacturer ’s instructions to protect against dentin exposure. An uncomplicated crown fracture (figs. 9.6 a, b) occurs when a fracture of the crown does not expose the pulp but extends into the dentin. Bacteria have an indirect pathway to the pulp through the dentinal tubules. If the injury is recent and a pink spot (pulpal blush) is evident on the fracture site, a near-pulp exposure is present. If untreated, the pulp may become necrotic, eventually appearing as a dark spot through the thin dentin. In cats, the pulp chamber extends to just under the crown tip compared with that of mature dogs, which usually have

a

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several millimeters of protective dentin under the enamel. For this reason even fractures that do not show gross pulp exposure are considered contaminated, necessitating root canal therapy or extraction. The patient’s age also affects the treatment plan. When intraoral radiographs do not reveal periapical pathology and the patient is less than nine months old, a dentinal bonding agent can be applied to the injured site and covered with composite. If the cat is between nine months and six years old, root canal therapy can be performed with generally favorable results. Alternatively, indirect pulp capping using a bonding agent and restorative agent is performed. When indirect pulp capping procedures are used, follow-up radiographs should be taken at six-month intervals after treatment for several years to examine the pulp chamber for internal resorption and pathology of periapical structures. When intraoral radiographs do not reveal periapical pathology and the patient is older than six years, a wait-and-see approach can be initiated. Those that are older than six years with fractures that just enter the dentin usually have sufficient dentin between the fracture and pulp, alleviating the need for root canal therapy. When periapical pathology exists with a radiographically closed apex, and if the patient is older than nine months, root canal therapy and crown restoration are the treatments of choice, usually resulting in a saved, nonpainful tooth. When periapical pathology radiographically exists and there is an open apex (fracture occurred before the patient was nine months old), either tooth extraction, an apexification procedure, or surgical endodontic care is performed. In uncomplicated crown-root fractures, the fracture involves enamel, cementum, and dentin, extending from the crown subgingivally into the root without exposing the pulp (fig. 9.7). Treatment is similar to the uncomplicated crown fracture; however, additional treatment may be necessary to treat the subgingival area void of cementum and dentin due to the fracture extension. The goal of therapy in this area is to remove significant periodontal pocketing either through gingivectomy (providing that at least 2 mm of attached gingiva remain) or an apically positioned flap.

Complicated Tooth Fractures b Figure 9.6 a. Uncomplicated crown fracture illustration. b. Complicated and uncomplicated canine fractures.

Complicated crown fractures have pulp exposure (fig. 9.8a). The pulp usually appears as a red (vital pulp often a recent injury) or black/brown spot (usually an older injury) on the fracture site. When pulp exposure exists,

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a Figure 9.7

Uncomplicated crown-root fracture illustration.

endodontic therapy should be performed (vital pulp therapy, standard root canal therapy, or surgical root canal therapy) or the tooth extracted (figs. 9.8 b–l). In complicated crown fractures, there is direct communication between the oral bacterial environment and the pulp. The bacterial exposure frequently leads to irreversible pulpitis, pulp necrosis, apical granuloma formation, periapical abscessation, and pain. The process may occur within a month or may be prolonged, smoldering for years (figs. 9.8 m–q). A complicated crown-root fracture occurs when the crown and root are fractured and there is pulp exposure. Treatment for complicated crown-root fractures is the same as for complicated crown fractures, with additional attention to the developing periodontal pocket at the subgingival fracture site (fig. 9.9).

b Figure 9.8 a. Complicated crown fracture illustration. b. Chronic hyperplastic pulpitis (pulp protruding through the fracture site) of the right maxillary fourth premolar treated with tooth extraction. c. Vertical releasing incision. d. Sulcular incision. e. Application of molt elevator. f. Molt elevator used to separate attached gingiva from underlying alveolar bone. g. Removal of the buccal coronal alveolus. h. Sectioning of the maxillary fourth premolar. i. Sectioned tooth. j. Wing-tipped elevator utilized to deliver the sectioned crown-root segments. k. Tooth fully extracted (note smooth apices). l. Removing the sharp alveolar margins with a high-speed, water-cooled round bur before suturing. m. Rostral mandibular swelling. n. Pustular discharge from the ventral mandible. o. Left mandibular complicated crown fracture. p. Radiograph revealing marked internal and external resorption. q. Extracted canine.

c f

g d

e

h Figure 9.8 Continued

203

l

i

m

j

n

k Figure 9.8 Continued

204

o

Figure 9.9

Complicated crown-root fracture illustration.

p

q Figure 9.8 Continued

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Figure 9.10 Root fracture illustration.

Root fractures are classified by the anatomic location of the fracture (coronal, middle, or apical third) and usually have pulp exposure. Coronal root fractures often present with a mobile crown (fig. 9.10). Treatment usually consists of tooth extraction and removal of the fractured coronal and apical root fragments.

Figure 9.11 Radiograph of a complicated right maxillary canine tooth fracture in seven-month-old cat.

exposure and closed root apices can be treated with standard root canal therapy.

Age of the Patient Age of the patient is also important when choosing endodontic therapy options. Canine teeth of patients younger than nine to twelve months of age may have open root apices (fig. 9.11). Mandibular molar teeth generally have closed apices by seven months of age. Standard root canal therapy is not performed on cat teeth with open root apices because appropriate sealing of the apex cannot be assured. Treatment options for teeth with open root apices include (1) vital pulp therapy (partial coronal pulpectomy, direct pulp capping, and restoration) to promote apexogenesis in a tooth with vital pulp or (2) an apexification procedure if the pulp is dead. Teeth with pulp

Age of the Fracture Age of the fracture influences endodontic treatment. Shortly after pulp exposure, inflammation occurs less than 2 mm from the exposure site. In acute fractures, the pulp appears pink or red at the fracture surface. The pulp of a long-standing fracture will appear brown or black. Vital pulp tissue can be found several millimeters deeper within the pulp, which might respond to vital pulp procedures (i.e., vital pulp therapy). In the mature animal that has an acutely or chronically fractured tooth with a closed apex, standard root canal therapy results in a more predictable outcome compared to vital pulp therapy.

Treatment of Endodontic Disease

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a

b

c

Figure 9.12 a. Paper points. b. Gutta percha points. c. Tooth obturated with gutta percha.

Materials for Endodontic Therapy Paper Points Paper (absorbent) points are rolled sterile papers used to absorb irrigation solutions in the prepared root canal. Paper points are long, narrow, and tapered to fit into the root canal (fig. 9.12a).

Gutta Percha Points Gutta percha points are slender, tapered, and pointed to fit to the contours of the root canal when compressed. Gutta percha is a combination of zinc oxide (66%), gutta percha rubber (23%), and radiopaque barium sulfate (11%). Gutta percha advantages include being an inert material, radiopaque, nonirritating, and removable for retreatment if root canal therapy fails (figs. 9.12 b, c).

Mineral Tri-Oxide Aggregate (MTA) MTA is composed of a calcium and silicate. It is supplied as a powder, which when hydrated sets in two to four hours. When set, MTA is biologically compatible with adjacent tissues and can be used in vital pulp therapy (direct pulp capping), surgical endodontics, root perforations, and one-step apexification procedures. Calcium hydroxide can also be used in a similar fashion as MTA and has many uses for feline endodontic care. Calcium hydroxide offers the following features:

•

Can be used (1) during the apexification procedure to stimulate hard tissue closure of an open apex in a nonvital tooth and (2) in apexogenesis to stimulate dentinal bridge formation under a direct pulp capping and hard tissue closure of an open apex in a vital tooth.

Sodium Hypochlorite (Bleach) Zinc Oxide–Eugenol Zinc oxide–eugenol (ZOE) is a cement that acts as a sealer between the gutta percha and root dentin. Endodontic sealing cement is also available without eugenol.

Sodium hypochlorite (common household bleach) acts as a solvent for necrotic tissue, a lubricant, and disinfectant for irrigation of the root canal. Depending on the practitioner ’s preference, sodium hypochlorite may be

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diluted with one to two parts distilled water or be used without dilution as it comes from the bottle. To apply sodium hypochlorite, a sterile 1-cc disposable plastic syringe with a blunt 20–23 gauge endodontic needle is used. The needle may be bent at an angle to facilitate access to the canal. Care should be taken not to apply excessive pressure on the syringe contents. Damage to the periapical structures may occur if sodium hypochlorite solution is pushed out of the apex into the periapical tissues.

Ethylenediaminetetracetic Acid (EDTA) EDTA is available in a liquid and a gel. The gel is used as a file lubricant, a dentin softening agent, and an effervescent that helps lift debris from the root canal. It can be introduced by dipping the files into the gel. The liquid is used to remove the smear layer from the root canal wall after filing and is introduced using endodontic flushing needles on a syringe.

Instruments for Endodontic Therapy The goal of standard root canal therapy is to remove toxins, microbes, and necrotic debris by thoroughly debriding the root canal(s) and then sealing the space to prevent further infection. Burs, files, broaches, spreaders, and pluggers are used to accomplish this goal. It is essential that endodontic instruments and accessories be sterile before placement into the root canal. A sterilized endodontic pack is prepared with the necessary instruments.

Endodontic Files Endodontic files are used to enlarge, debride, shape, and smooth the root canal. Kerr (K) files and Hedstrom (H) files are most commonly used. K files cut or shave the root canal walls during rotation. They are applied in a push-pull or clockwise quarter rotation push-rotate fashion to pull dentin debris coronally. The file is extended to its root canal apex before withdrawal. Files come in various lengths and sizes. K files are stronger and more flexible than H files and less prone to breakage. File length chosen depends on the root canal length from tooth access to its apex. Files can be purchased in groups of five in one size or assorted sizes. H files are sharper than K files. They cut efficiently and quickly, and they are used when significant removal of dentin is desired, such as enlarging the access in the coronal third of the tooth. H files are not intended for use in the apical third. They cut on the up (pull) stroke

Figure 9.13

Endodontic files.

(K files cut on both clockwise and counterclockwise rotations and on insertion and withdrawal). To prevent a corkscrew apical penetration, H files should not be rotated (fig. 9.13). Nickel titanium (NiTi) files have become the preferred file of choice for many human and veterinary dentists. These instruments are used by hand or in a powered handpiece at speeds ranging from 150 to 2000 rpm. NiTi files, available in H or K varieties, are more flexible than files made from stainless steel. The International Standards Organization (ISO) sets standardization from one manufacturer to another regarding lengths and widths of flutes, taper, relationship between successive sizes, and coloration. Most files are purchased with color-coded handles, which correlate with various widths. ISO width sizes are numbered 8 to 140 (0.8–1.4 mm at the tip). File handle color correlates to the diameter at the working end (e.g., all #10 file handles are purple, #15 are white, #20 are yellow, and so on). Standard ISO file widths typically increase in 0.05-mm increments (15, 20, 25, etc.). It would be rare to need to use a file greater than size 50 in the cat.

Treatment of Endodontic Disease

Files are also measured by lengths. Human dental files are sized 21, 25, and 30 mm, sufficient for working on feline companion animal patients. With repeated use, endodontic files fatigue and eventually separate (break). As instruments are prepared for sterilization, they should be individually checked for signs of wear, weakness, or fracture. Some practitioners color code the files with endodontic stops relating to the number of times each file is used. The safest practice is to use new files with each patient. To mitigate the expense of using fresh files for each case, a sterile endodontic surgical pack fee can be charged to the client. Should the instrument separate within the root canal, retrieval is attempted. In some cases, apical surgery or extraction of the tooth becomes necessary.

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a

Endodontic Stops Endodontic stops are small, round pieces of rubber or plastic that act as visual stopping point references to assist the veterinarian in preparing the canal. The stops are placed toward the file handle and the file is placed into the root canal to make a confirming radiograph before root canal therapy is initiated. The stop is readjusted when the file is at the internal end of the apex, as confirmed by a working-length radiograph. All succeeding files are fitted with endodontic stops at the working length. Some of the newly designed instruments, such as LightSpeed, have length-measuring rings, eliminating the need to set and reset stops during treatment.

Spreaders and Pluggers Spreaders and pluggers are available in multiple diameters and lengths, used to compact and adapt gutta percha to the prepared root canal. The smooth-pointed spreader is a hand-operated, tapered metal instrument that compacts gutta percha laterally into the root canal space, forcing sealant into apical and nonapical ramifications and dentinal tubules, and creates room for insertion of additional gutta percha. The blunt-tipped plugger compacts gutta percha vertically toward the apex (figs. 9.14 a, b). For feline teeth, which are short, human pluggers and spreaders can be used.

College Pliers College pliers, also called cotton pliers or endodontic locking pliers, enable the operator to pick up and hold paper or gutta percha points in place for insertion into the prepared root canal. Pliers can also be used for holding cotton pledgets for cleaning tooth surfaces.

b Figure 9.14

a. Spreader. b. Plugger (Cislak).

They are available in both locking and nonlocking styles, with plain or serrated tips (fig. 9.15).

Spatulas Spatulas are instruments used to mix dental materials. Cement spatulas are thin and nonflexible (fig. 9.16).

Irrigation Needles Irrigation needles (available in 23, 25, 27 guage sizes) are used to flush fluids into the canal in order to remove dentinal shavings and debris that accumulate during instrumentation. Irrigation needles have a slotted tip or a lateral opening for fluid to exit around the needle and not through the apex, preventing apical damage from overzealous irrigation.

Vital Pulp Therapy Vital pulp therapy involves partial pulpectomy, direct pulp capping, and restoration.

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• • • • •

Paper points Retrograde amalgam carrier Chlorhexidine solution (0.12%) Calcium hydroxide powder or MTA Restorative material

Technique Vital pulp therapy has limited use in the cat. It can be used for treatment of acutely (treatment within hours of injury) fractured teeth and surgical crown reduction for orthodontic care. 1. 2. 3. 4.

5. Figure 9.15 College-tipped pliers (Cislak).

6.

7. 8.

9.

10. 11.

Figure 9.16 Spatula with zinc oxide–eugenol cement.

Instruments and Materials

• • •

701, #1 and #2 round carbide burs Sterile saline Cotton dressing forceps

12.

Administer parenteral pain medication preoperatively. Obtain an intraoral dental radiograph to determine root maturity and to evaluate dental pathology. Clean and polish the teeth ultrasonically. Infuse a local anesthetic with epinephrine around the tooth or perform a nerve block to desensitize the pulp. Disinfect the oral cavity with 0.12% chlorhexidine gluconate antiseptic solution. A sterile punctured glove may be placed over the crown. Access directly through the exposed pulp with a #1 or #2 sterile round bur in a sterile high-speed handpiece under sterile saline irrigation (figs. 9.17 a, b, c, d). Remove 3 mm of coronal pulp tissue, using a round or diamond bur (fig. 9.17e). To control pulpal bleeding, irrigate the pulp chamber with cold sterile saline initially; follow by applying sterile paper points to absorb hemorrhage. Bleeding that is not controlled within five minutes might be indicative of an inflamed pulp that might not be treatable by vital pulp therapy. Gently apply 2 mm of calcium hydroxide (CaOH) powder with a retrograde amalgam carrier on top of the exposed vital pulp. MTA can also be used instead of CaOH. Slightly undercut the access area to prepare for placement of the final restoration (figs. 9.17 f, g, h). Restore the tooth with a light-cured composite resin; the final restoration layer should be at least 2 mm thick (fig. 9.17i). Obtain a final radiograph. Send the patient home with pain control and prophylactic antibiotic medication.

The tooth is examined and radiographed at six months postoperatively and every year or two opportunity arises during future oral hygiene procedures. In the immature tooth, a radiographic visible dentinal bridge often forms below the restoration. The presence of a

a

c

b

d

Figure 9.17 a. and b. Mandibular canine tooth before crown reduction to prevent upper lip impingement after maxillary canine extraction. c. Cross-cut fissure bur used to reduce the crown height. d. Crown height reduced. e. Inverted cone bur used to remove 3–5 mm of the coronal pulp. f. Retrograde amalgam plugger used to administer calcium hydroxide over the excised pulp. g. Inverted cone bur used to prepare the tooth for restoration. h. Appearance of calcium hydroxide before restoration. i. Restored tooth.

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e

g

h

f

Figure 9.17 Continued

212

i

Treatment of Endodontic Disease

dentinal bridge does not guarantee success. On sequential radiographs, the root canal of a vital tooth should appear narrower because of continued dentin production. Apexogenesis (root development and apical closure) is the desired outcome when vital pulp tissue is exposed in a young cat (