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Dentistry Sandra Manfra Marretta, DVM, Diplomate ACVS, AVDC University of Illinois Recognition and Treatment of Canine Dental and Oral Pathology The recognition and treatment of canine dental and oral pathology is an important component in successful management of canine health. Many dental and oral lesions occur frequently in dogs but may have a variety of presentations and treatment options. Commonly occurring canine dental and oral lesions include: variations in number of teeth and roots, periodontal disease, endodontic disease, dental caries, dental attrition/abrasion, discolored teeth and oral masses (benign and malignant). Variations in Number of Teeth and Roots Dogs normally have 42 adult teeth. The permanent dental formula in the dog is as follows: 2(I3/3C1/1P4/4M2/3). Oligodontia or decreased number of teeth is more common in dogs than cats. Although oligodontia is not a serious medical problem, it can be a problem for breeders since it is considered a genetic imperfection. Puppies with missing deciduous teeth will also be missing the same adult teeth. Supernumerary teeth or extra teeth may result in crowding and malalignment of teeth predisposing to the development of periodontal disease. Various teeth in the dog may be supernumerary. Supernumerary teeth that are not causing crowding or malalignment of teeth require no treatment. Supernumerary teeth that result in crowding should be extracted. Prior to extraction supernumerary teeth should be radiographed to evaluate their root structure. It is important to differentiate supernumerary teeth from overly retained deciduous teeth. In dogs, the canine teeth are the most frequently retained teeth, however, the incisors and premolars may also be retained. Retained deciduous teeth should be extracted as soon as they are diagnosed so that permanent teeth may erupt into their normal positions. When retained deciduous teeth are not removed, permanent teeth are deflected lingually, except maxillary canine teeth, which are deflected rostrally. Deciduous teeth are smaller than their permanent counterparts. When difficulty is encountered in determining which tooth is deciduous and which tooth is permanent a dental radiograph should be taken. The root of the permanent tooth in a 6-month-old animal will have a wide pulp canal with thin dentinal walls and an open apex compared to the deciduous teeth which will have a much thinner but more developed root. Occasionally teeth may have extra roots this condition is known as supernumerary roots. Supernumerary roots are generally incidental findings on oral examination and generally occur as extra roots in teeth that normally have only two roots. It is important to recognize the normal and abnormal root structure in teeth requiring extraction. This permits appropriate sectioning prior to extraction. Dental radiographs can also assist in the localization of supernumerary roots. Periodontal Disease Periodontal disease is the most common disease affecting dogs today. The common clinical presentations of periodontal disease in the dog include mobile teeth, periodontal and periapical abscesses with secondary facial swelling, gingival recession and furcation exposure, mild to moderate gingival hemorrhage, and deep periodontal pockets with secondary oronasal fistulas resulting in a secondary chronic rhinitis. Less frequently, severe gingival sulcus hemorrhage, pathologic mandibular fractures, painful contact buccal mucosal ulcers, intranasal tooth migration, and osteomyelitis have been reported. The treatment of periodontal disease is based on one major factor: a clean periodontium results in a healthy periodontium. There are numerous treatment modalities associated with the management of periodontal disease. These treatment modalities include: supragingival and subgingival scaling, root planing, subgingival curettage, polishing/irrigation, gingivectomy, open-flap curettage with augmentation of bony defects, treatment of endodontic/periodontic lesions, perioceutics, exodontia, oronasal fistula repair, and home care. Prior to administration of various treatment modalities for periodontal disease a thorough assessment of the patient's general health stasis is mandatory. Many animals with periodontal disease may have concurrent problems including diabetes, cardiopulmonary problems, hepatic, renal, and other metabolic problems. Once these diseases are recognized and managed appropriately, anesthetic protocols can be selected based on the individual patient's requirements. Endodontic Disease Endodontic disease refers to disease of the pulp, the inner aspect of the tooth. Dental trauma with or without pulpal exposure is the most common cause of endodontic disease in dogs. The canine teeth and the maxillary 4th premolars are the most frequently fractured teeth in dogs. Depending on the amount of tooth structure fractured off the pulp may or may not be exposured. A dental explorer is used to determine if the pulp has been exposed. Fractured teeth are often noted as an incidental finding on physical examination. However, a series of events may occur in some fractured teeth with exposed pulp which can result in significant clinical presentations. This series of events includes the following conditions: (1) exposed pulp, (2) bacterial pulpitis, (3) pulp necrosis, (4) periapical granuloma, (5) periapical abscess, (6) acute alveolar periodontitis, (7) osteomyelitis, and (8) sepsis. The time required for this progression varies from months to years. When a tooth is fractured and the pulp is exposed the pulp will bleed. Pulpal exposure is extremely painful and animals with an acutely fractured tooth with pulpal exposure will hypersalivate, be reluctant to eat, and exhibit abnormal behavior. Over several months the pulp becomes necrotic and the animal is no longer painful until an inflammatory reaction occurs around the apex of the tooth at which time the animal becomes painful again. An endodontically diseased tooth is not only painful but it also is a potential source of infection for other parts of the body. An endodontically diseased tooth may present clinically as a discolored tooth which is painful on percussion. Soft tissue fistulas may occur secondary to endodontic disease. These fistulas are usually located apical to the mucogingival line. Endodontically diseased teeth may present with severe maxillary or mandibular swelling. Endodontically diseased teeth may also cause nasal discharge or hemorrhage or ophthalmic signs. All endodontically diseased teeth should be either treated or extracted. Dental Caries Dental caries is demineralization of the tooth and results in subsequent loss of tooth structure. Early dental caries may appear as a dark brown spot and have a sticky or slightly soft feel when probed with a dental explorer. Once dental caries perforates the enamel, the caries can progress rapidly in the dentin, destroying the tooth and eventually resulting in pulpitis and pain. This may be followed by pulp necrosis and periapical infection. The teeth most commonly affected in dogs with dental caries are the maxillary first molar, and the mandibular first and second molars. When dental caries occur in the dog, the lesions are often multiple and advanced. Dental radiographs should be taken of teeth with dental caries to rule out any associated endodontic pathology. Treatment of dental caries includes extraction or restoration of affected teeth. Dental Attrition/Abrasion and Cage-Biter Syndrome Dental attrition is the gradual and regular loss of tooth substance resulting from normal mastication. Excessive wear caused by malocclusion resulting in tooth-to-tooth contact is called pathologic attrition. Dental abrasion is the mechanical wear of teeth caused by mechanical wear other than by normal mastication or tooth-to-tooth contact such as wear caused by chewing rocks, cage bars, or wire. In cases of dental attrition the pulp responds to rapid wear by laying down tertiary or reparative dentin, which is visible as a dark brown spot on the affected tooth. The dark brown spot is solid and cannot be entered with a dental explorer. No therapy is usually required in these cases. Occasionally, very rapid dental attrition can result in pulpal exposure. These cases require endodontic therapy or extraction. Cage-biter syndrome can be seen in dogs who chronically chew on their cage bars. The unique pattern of dental wear associated with cage-biter syndrome includes dental wear on the distal aspect of the canine teeth. Dogs affected by severe wear on the distal aspect of their canine teeth may be affected with dentinal hypersensitivity, endodontic disease, and crown weakening resulting in dental fractures. Dental radiographs should be taken of teeth affected with cage-biter syndrome to help rule out the presence of endodontic disease. If endodontic disease is present, affected teeth should be endodontically treated or extracted. Full or three-quarter prosthetic crowns can be placed on teeth affected with cage-biter syndrome. A three-quarter crown is preferred in teeth that are not endodontically treated so that if endodontic treatment is required at a later date the ideal access site can be easily created without damaging the prosthetic crown. Discolored Teeth Hemorrhage or necrosis of the pulp results in lysis of red blood cells. This results in hemoglobin breaking down into pigments which penetrate into the dentinal tubules and result in a variety of discolorations of the affected tooth. The color of the traumatized crown may vary from pink-red to blue-gray or dark gray. When intrapulpal hemorrhage is minor the pulp may remain vital and the blood pigment may be resorbed and the crown discoloration may be temporary. In a recent clinical study reviewing the incidence of localized intrinsic straining of teeth due to pulpitis and pulp necrosis in dogs, it was found that a distinct majority of teeth (92.2%) with pink/grey/tan crown discoloration had either partial or total pulp necrosis based on visual examination of the pulp during root canal therapy or exploratory pulpotomy. However, radiographic signs of endodontic disease were not present in 42.4% of affected teeth indicating that dental radiographs should not be relied upon to indicate pulp vitality in discolored teeth. This study recommended that all discolored teeth receive either endodontic or exodontic therapy. An obvious concern for practicing this treatment rationale routinely would be that vital, discolored teeth may undergo unnecessary endodontic therapy or extraction. However, the risk of unnecessary dental treatment would be acceptably low (<10%) in exchange for the assurance of potential pain alleviation. Yellowish discoloration of teeth may be caused by tetracycline staining. When tetracycline is administered during pregnancy and the development of deciduous and permanent teeth, the tetracycline will combine with the calcium in the teeth to form a tetracycline-calcium orthophosphate complex that results in a yellowish discoloration of the teeth. To prevent tetracycline staining of teeth avoid administering tetracycline to pregnant and young animals. Enamel hypolasia is defined as an incomplete or defective formation of the organic enamel component. Enamel hypoplasia is caused by disruption of the ameloblasts during the first several months of life while the teeth are developing which may be associated with periods of high fever, infections (especially canine distemper), nutritional deficiencies, disturbances of the metabolism, and systemic disorders. Shortly after eruption, the soft, brittle enamel peels off exposing the underlying dentin which is soon stained yellowish-brown by extrinsic factors. In cases of enamel hypoplasia, there exists a deficiency in the thickness of the enamel: the defects in the enamel can be limited to a circumscribed area or be recognized as a single narrow zone of smooth or pitted hypoplasia. Disturbance in enamel formation over a longer period of time results in a more generalized distribution of lesions. When enamel hypoplasia is limited to a solitary tooth the most likely cause is trauma. Benign and Malignant Oral Masses Oral tumors occur frequently in dogs and cats. Oral tumors account for approximately 6% of all malignant tumors in dogs with malignant cancer of the mouth and pharynx occurring 2.6 times more frequently in dogs than in cats. Oral tumors may be benign or malignant. Unfortunately, diagnosis of oral malignancies frequently occurs when the tumor is quite advanced, necessitating more extensive treatment. Thorough oral examination during routine physical examinations and during dental procedures can permit early detection of oral tumors providing patients with a better prognosis. Early diagnosis of oral tumors, appropriate staging, wide surgical resection and alternative treatment modalities can improve survival time. When an oral mass is detected during a routine dental procedure a dental radiograph should be taken to determine the presence of underlying boney lysis which may be seen with malignant oral tumors. The mass should be biopsied to determine whether or not the tumor is benign or malignant. Biopsy of large oral masses must be deep, because superficial biopsies may reveal only inflammation or gingival hyperplasia. A deep wedge biopsy or a deep Tru-cut is recommended. The use of electrosurgery for obtaining oral tumor biopsies is not recommended. Non-neoplastic reactive lesions that occur as a result of chronic low-grade irritation such as focal fibrous gingival hyperplasia and pyogenic granulomas occur at the gingival margin and are treated with a gingivectomy and treatment of the underlying cause of the inflammation which is most frequently periodontal disease. Sublingual and buccal mucosal areas of excessively loose mucosal folds that are indurated and hyperplastic secondary to repeated self-inflicted trauma have also been described as "gum-chewers lesions" because the behavior of dogs with these lesions may mimic that of a person aggressively chewing gum. These lesions may become quite large and may be painful when they are repeatedly traumatized by chewing on the lesions with the molar teeth. When these lesions become ulcerated and become a source of pain for the patient surgical excision is recommended. The resected tissue should be submitted for histopathologic evaluation to rule out the presence of neoplasia. Malignant oral tumors require more aggressive surgical treatment to help prevent local recurrence including various partial mandibulectomy and maxillectomy procedures depending on the location of the oral tumor. It is important to properly stage all dogs suspected of having malignant oral tumors to rule out distant metastasis. References:
Recognition and Treatment of Feline Dental and Oral Pathology The recognition and treatment of feline dental and oral pathology is an important component in successful management of feline health. Many dental and oral lesions occur frequently in cats but may have a variety of presentations and treatment options. Commonly occurring feline dental and oral lesions include: variations in number of teeth and dental abnormalities, periodontal disease, odontoclastic resorptive lesions, fractured teeth, mandibular swelling, lymphocytic plasmacytic stomatitis, nasopharyngeal polyps, and feline oral neoplasia. Variation in Numbers of Teeth and Dental Abnormalities Abnormalities in the number of teeth in cats can be inherited, or can result from disturbances during the initial stages of tooth formation. Complete absence of all teeth, and decreased number of teeth, oligodontia, are uncommon in cats. Supernumerary teeth are more common, and may result in crowding and malalignment of teeth with the early development of periodontal disease. The mandibular fourth premolars appear to be the most common supernumerary teeth in the cat. Supernumerary teeth that result in crowding should be extracted early. Persistent deciduous teeth should also be extracted. Abnormalities in development of teeth occur rarely in cats. Gemination is a disorder in which the developing tooth bud attempts to split but fails to do so completely, resulting in duplication of part of the tooth but not complete twinning. Gemination teeth commonly have two crowns, each with a separate pulp chamber merging into a common root canal system which can be demonstrated radiographically. In the cat, gemination appears to most frequently affect the maxillary 3rd, and mandibular 4th premolars. When gemination occurs in these teeth they have two normal sized roots mesially and distally and one large common centrally located root which can be demonstrated radiographically. Occasionally teeth may have extra roots this condition is known as supernumerary roots. Supernumerary roots are generally incidental findings on oral examination and generally occur as extra roots in teeth that normally have only two roots. It is important to recognize the normal and abnormal root structure in teeth requiring extraction. This permits appropriate sectioning prior to extraction. Dental radiographs can also assist in the localization of supernumerary roots. Periodontal Disease Periodontal disease can be divided into two categories: gingivitis and periodontitis. Gingivitis is confined to gingival tissue, while periodontitis is a more severe form of disease involving loss of bone supporting the tooth. Cats with periodontitis, in addition to having gingivitis, may have gingival recession or increased pocket depth, alveolar bone loss, exposure of roots and furcations, tooth mobility, and eventual tooth loss. A periodontal probe is used to assess the level of attachment loss, and measure pocket depth. The prevention and treatment of feline periodontal disease consists of regular dental prophylaxis every 6 to 12 months. A thorough dental prophylaxis can only be performed under general anesthesia and consists of supragingival and subgingivial scaling, subgingival curettage, root planning and polishing the teeth. Broad spectrum perioperative antibiotic therapy is recommended perioperatively. Two additional abnormalities may be associated with feline periodontal disease, and can complicate treatment significantly. These abnormalities are oral inflammatory diseases and odontoclastic resorptive lesions. When periodontal disease is complicated by either of these conditions, exodontia is the treatment of choice. In cats, dry-food diets, especially tartar control diets, result in improved gingival health compared to a soft-food or semi-moist diet. In addition, daily brushing to remove plaque is ideal. Odontoclastic Resorptive Lesions Odontoclastic resorptive lesions are one of the most common dental lesions in cats. A report reviewing 10 independent surveys of odontoclastic resorptive lesions revealed that 20 to 67 per cent of all cats have 1 or more lesions with a mean of 2.3 to 4.1 lesions per affected cat. Feline odontoclastic resorptive lesions are characterized by a clinically or radiographically evident defect in the enamel, dentin and/or cementum. These lesions may be hidden from view by plaque, dental calculus or inflamed gingival tissue. Clinically, resorptive lesions are areas in which tooth substance is missing and may be seen as actual absence of tooth substance or the missing hard tooth tissue is replaced with granulation tissue. A dental explorer is gently moved over the surface of the tooth within the gingival sulcus to detect these lesions and when a resorptive lesion is encountered it will fall into the irregular area of resorption and in some cases the lesion becomes quite apparent when an undercut area of cementum and dentin is penetrated, producing an overhang of enamel. These teeth should be radiographed to determine the full extent of the defects. Whole tooth extraction is considered to be the treatment of choice for teeth with severe odontoclastic resorptive lesions. These teeth are weak, brittle and often ankylosed to the alveolar bone making extraction difficult which may result in iatrogenic trauma to the patient, loss of alveolar bone, and prolonged healing of surgical defects. A recent study by DuPont investigated the intentional retention of part or all of non-pathologic tooth roots following amputation of the crown of affected teeth and reapposition of the gingiva with 3-0 chromic. In this study 51 roots from 23 teeth were radiographed 5-36 months following elective root retention; continued resorption without surrounding bony reaction was seen in almost all cases. In one case, the roots retained normal periodontal ligament one year later; and in another case severe stomatitis developed and the intentionally retained roots were extracted at the same time that the remaining molar teeth were extracted. Utilization of the DuPont technique requires preoperative dental radiographs to rule out evidence of endodontic pathosis. Teeth with endodontic pathosis, as evidence by the presence of periapical lysis, or teeth with periodontal pocketing must be treated by extraction rather than crown amputation with intentional root retention. Also cats affected with ulceroproliferative disease are not candidates for this technique. These cats require that all root structure and possibly the surrounding alveolar bone be completely removed. After radiographing feline teeth with advanced odontoclastic resorptive lesions and ruling out the presence of endodontic pathosis and periodontal pocketing a very small envelope flap is created with a small feline periosteal elevator. Two small interproximal gingival incisions located mesial and distal to the affected tooth are made using a #15 blade. The gingiva is minimally elevated from the tooth and marginal alveolar bone with a small feline periosteal elevator. The gingiva is retracted and protected with the end of a small flat elevator while the crown of the affected tooth is amputated with a #3 round bur on a high speed handpiece with sterile water flush at or slightly below the level of the alveolar crest. Sharp bony projections are smoothed with the bur and the gingiva is closed with two simple interrupted 4-0 chromic sutures. Clients should be advised when utilizing the DuPont technique that if pathology develops around the intentionally retained root that future removal will be necessary. Fractured Teeth Fractured canine teeth usually result in pulpal exposure in cats because of the extension of the pulp canal into the coronal tip of the canine tooth in felines. Pulpal exposure is confirmed if a fine dental explorer penetrates into the canal. Teeth with confirmed pulpal exposure should be extracted or treated endodontically. Prior to endodontic therapy radiographs must be taken to ensure that the apex is intact. Failure to treat fractured teeth with pulpal exposure may result in periapical abscessation, mucosal or cutaneous fistulation, chronic rhinitis, osteomyelitis, and ocular discharge. Mandibular Swelling Feline mandibular swelling is not readily recognized because of the ventral location of the mandible. Without careful palpation of the ventral aspect of the mandible, mandibular swelling may not be detected. Feline mandibular swelling may be benign or malignant. The most common cause of benign mandibular swelling in cats is osteomyelitis secondary to retained odontoclastic resorptive tooth roots and less frequently secondary to periodontal disease and endodontic disease. The most common cause of malignant feline mandibular swelling is squamous cell carcinoma and less frequently fibrosarcoma, lymphosarcoma, and osteosarcoma. Thorough oral examination, dental radiography, and intraoral incisional biopsy will help provide a definitive diagnosis. Treatment of feline mandibular swelling is dependent upon an accurate diagnosis. Benign mandibular swelling associated with dental disease requires recognition of diseased teeth. Thorough oral examination with periodontal probing and examination with a dental explorer will assist in the recognition of periodontal pockets, pulpal exposure and retained root tips associated with Stage V odontoclastic resorptive lesions. Treatment of feline mandibular swelling associated with dental disease requires extraction of associated teeth. Feline Perialveolar Osteitis A severe firm swelling around the root of the maxillary canine tooth may occur in middle-aged and geriatric cats. This bulbous maxillary canine tooth perialveolar swelling often occurs bilaterally and may be associated with periodontal or endodontic disease and should not be mistaken for neoplasia. Periodontal probing and dental exploration of the affected maxillary canine teeth often reveals a deep periodontal pocket or chronic pulpal exposure. A dental radiograph may reveal loss of trabecular bone pattern around the roots of affected maxillary canine teeth with a thin line of sclerotic bone surrounding the periradicular bone loss. Treatment includes extraction of the affected tooth, curettage and flushing of the alveolus with sterile saline. The firm perialveolar swelling may partially remodel over time however significant chronic residual swelling usually remains. Lymphocytic Plasmacytic Stomatitis Cats with lymphocytic plasmacytic stomatitis (LPS) typically present with a history of halitosis, ptyalism, dysphagia, inappetence and weight loss. Oral examination reveals a hyperemic, proliferative ulcerative mucosa with a raspberry red, cobblestone appearance. These lesions may be primarily around the dentition but may extend onto the palatoglossal folds and fauces. The etiology is unknown. Histologically, this condition is characterized by infiltration of affected tissue with large numbers of lymphocytes and plasmacytes. The serum proteins are high because of severe elevations in the globulins. Cats with lymphocytic plasmacytic stomatitis should be tested for feline leukemia virus and feline immunodeficiency virus, although many test negative. Cats with LPS often lack a permanent response to conventional oral hygiene, antibiotics, anti-inflammatory drugs, and immunomodulators. Refractory cases frequently necessitate extraction of at least all the premolars and molars and in some cases extraction of the entire dentition including removal of all root tips and debridement of reactive bone is required. Lack of a known causative agent, severe disease with possible underlying naturally occurring or acquired immunopathologies necessitates aggressive treatment. Various treatment modalities have been recommended for the management of lymphocystic plasmacytic stomatitis. Medical management including steroids and antibiotics, interferon, hypoallergenic diets combined with dental scaling and polishing and home care has been recommended. Laser therapy has also been recommended. Extraction of all cheek teeth or full mouth extraction may be utilized in refractory cases, however, persistence of clinical signs may occur especially in cases with pharyngeal involvement. These cases are often difficult to manage and often require multi-modality treatment options with only partial responses. Nasopharyngeal Polyps Nasopharyngeal polyps are an uncommon upper respiratory problem that is unique to cats, and occur most frequently in young cats. Nasopharyngeal polpys are non-neoplastic soft tissue growths that originate from the mucous membrane of the auditory tube or middle ear. The polyp may extend into the external ear canal, osseous bullae, or nasopharynx. Clinical signs associated with nasopharyngeal polyps include inspiratory stridor, sneezing, rhinitis, dysphagia, voice change, and head tilt or nystagmus. Diagnosis of nasopharyngeal polyps generally is based on history, clinical signs, and direct visualization of the polyp in the anesthetized patient. Forward displacement of the soft palate frequently reveals a firm smooth pink mass in the nasopharynx. Otoscopic examination may also reveal extension of the polyp into the external ear canal. The cause of nasopharyngeal polyps in cats is unknown. Nasopharyngeal polyps may develop secondary to chronic inflammation and local tissue irritation. Feline calicivirus has been identified in cats with nasopharyngeal polyps. The common occurrence of this virus in cats makes it difficult to support a cause and effect relationship. Because nasopharyngeal polyps occur most frequently in young cats, a congenital origin has also been suspected. Treatment options for nasopharyngeal polyps is dependent upon radiographic evaluation and localization of the polyp. Computerized tomography of the bullae are beneficial in assessing bullae involvement. If the polyp does not involve the bulla when assessed radiographically, it may be removed with gentle traction through the oral cavity or external ear canal. Unfortunately, many polyps invade the middle ear, necessitating ventral bulla osteotomy for complete removal. The feline tympanic bulla contains a septum that separates it into dorsolateral and ventromedial compartments. This septum must be opened to permit curettage and drainage of both compartments. Complete removal of a polyp warrants a favorable long-term prognosis. Postoperative complications that may occur following removal of nasopharyngeal polyps include: transient Horner's syndrome that often resolves spontaneously 3 to 6 weeks postoperatively, persistent otitis media possibly related to rupture of the tympanic membrane, regrowth of the polyp, and facial nerve paralysis. Nasopharyngeal Stenosis Cats with acquired nasopharygeal stenosis usually present with a history of nasal obstruction of several months' duration. The most significant clinical sign in these cats is a stertorous or wheezing upper respiratory noise. However, when the cat's mouth is held open the respiratory noise and distress are relieved indicating that the clinical signs are nasal in origin. Definitive diagnosis of nasopharyngeal stenosis is confirmed with a small-bore, flexible fiberoptic endoscope. The endoscope is placed dorsal to the caudal edge of the soft palate and directed rostrally. In normal cats the caudal nares are seen at approximately the level of the hard palate and form an ovoid orifice measuring about 6 mm dorsoventrally and 5 mm laterally in the adult cat. In cats with acquired nasopharyngeal stenosis the caudal nares is reduced to a pinhole-sized orifice by the presence of a thin but tough membrane. Attempts to pass a thin catheter from the external nares through the ventral meatus on each side will be unsuccessful in cats with nasopharyngeal stenosis. The treatment of choice for acquired nasopharyngeal stenosis is surgery. The cat is placed in dorsal recumbency with the mouth taped open. A midline incision is made in the soft palate and the cut edges are retracted laterally. The stenotic nasopharyngeal opening is enlarged by carefully excising the abnormal membrane with a fine iris scissors or a carbon dioxide laser. The soft palate is sutured with 4-0 Monocryl suture in two layers. Prognosis is good following removal of the nasopharyngeal web. Feline Oral Neoplasia Oral neoplasia occurs frequently in cats. By far the most common type of feline oral neoplasia is squamous cell carcinoma. The second most common feline oral neoplasia is fibrosarcoma. Other less common feline oral neoplasia include: lymphosarcoma, osteosarcoma, and melanoma. Treatment of feline oral neoplasia is early radical resection including mandibulectomy and maxillectomy procedures. Other potential treatment modalities include chemotherapy and radiation therapy. References:
Digital Dental Radiography Dental radiography is an essential component in the delivery of high quality dental care for dogs and cats. During the 1980s veterinarians began taking radiographs of teeth using standard radiographic units however these units made patient positioning difficult and often resulted in suboptimal films. In the 1990s dental radiographic units became a more common part of the veterinary dental diagnostic workup and by the year 2000 many state-of-the-art veterinary practices were switching over to digital dental radiography. This seminar will focus on the value of taking dental radiographs, how to take digital dental radiographs, special features available with digital dental radiographic units, advantages and disadvantages of digital dental radiography, indications for taking dental radiographs, positioning for optimal dental radiographs, critiquing dental radiographs and the importance of recognizing dental radiographic lesions. The diagnostic value of full mouth dental radiography in dogs and cats has been previously reported.1,2 It was found that the diagnostic yield of full mouth radiographs in feline and canine patients is high, and routine full mouth radiography is justified. These studies found that if disease existed, radiographs were clinically useful in 86.1% of the cases in the study (Table 1 & 2).1-3 VALUE OF RADIOGRAPHS WHEN NO CLINICAL FINDINGS PRESENT
Table 1 VALUE OF RADIOGRAPHS WHEN CLINICAL FINDINGS PRESENT
Table 2 How to Take Digital Dental Radiographs and Special Features Available There are two methods of acquiring digital dental radiographs, either DR (Digital Radiography) or CR (Computer Radiography). DR images are acquired by placing a sensor into the mouth in the same position as a film and exposing the sensor with a greatly reduced dose of radiation. The image is transferred within seconds for viewing on a computer. These images are then electronically stored and manipulated as needed for radiographic evaluation of a wide variety of dental lesions. CR images are an indirect way of acquiring digital dental radiographs. With this technology a reusable Phosphor Storage Plate (PSP) is exposed to x-rays and the PSP is then processed and converted to a digital image on a computer. The Scan X®, a digital radiography system, produces a digital image by scanning PSPs of various sizes (0,2,3 and 4) which have been exposed to x-rays. The Scan X® allows computer storage, processing, retrieval and display of the computed radiographic images utilizing a user supplied software package. The Scan X® also has an in-line plate eraser function that removes the latest image from the plate immediately after scanning providing an efficient one-step scanning and erasing process leaving the PSP ready for the collecting the next radiographic image. Digital dental radiographs can be manipulated for better visualization. The mouse can be used to adjust the contrast and brightness, a particular area of a tooth can be highlighted, magnified, labeled, flipped, rotated, measured or explanatory notes can be added . The advantages and disadvantages of digital dental radiography have been previously reported.3,4 Advantages of Digital Dental Radiography
Ideally full mouth radiographs should be taken on every patient, however, this may not be possible because of cost constraints or concerns for time under anesthesia in critically ill patients. Digital radiographs can help alleviate f these concerns because of the decrease in time needed to acquire digital radiographs. If full mouth radiographs are not taken there are several indications in which teeth should be radiographed. Dental radiography is recommended in the evaluation of odontoclastic resorptive lesions, the evaluation of periodontal disease including animals with nasal discharge, the evaluation of endodontic disease including discolored teeth and facial swelling, retained roots, missing teeth, abnormally located teeth, malformed teeth, osteomyelitis, boney lysis secondary to neoplasia, metabolic bone disease, localization of dentigerous cysts, and evaluation of traumatic injuries. Dental radiography is indispensible in the development of an appropriate treatment plan. Positioning for Optimal Dental Radiographs There are numerous publications that describe appropriate positioning for optimal dental radiographs.3-8 There are two specific intraoral radiographic dental techniques: the parallel technique and the bisecting angle technique. The ideal dental radiograph is produced by utilizing the parallel technique. When using the parallel technique the plane of the radiographic film is parallel to the long axis of the tooth and perpendicular to the plane of the radiographic beam. The parallel technique in dogs and cats can only be achieved with the mandibular premolars and molars. The flat shallow palate and the shallow caudally extending mandibular symphysis in dogs and cats prevent utilization of the parallel technique when radiographing the maxillary premolars and molars and the incisor and canine teeth. In these teeth the bisecting angle technique can be utilized. The film is placed as parallel as possible to the teeth being radiographed. An imaginary line that bisects the angle between the long axis of the tooth and the film is the bisecting angle line. The x-ray beam should be directed perpendicular to the bisecting angle line. Improper utilization of the bisecting angle technique will result in an elongated, foreshortened, or an overlapped radiographic dental image. A basic dental radiographic survey consists of six views: the rostral maxillary and mandibular projections, the right and left maxillary projections and the right and left mandibular projections. Additional radiographs may be necessary depending on the size of the patient. The upper fourth premolar requires additional radiographs to permit adequate visualization of all three roots. A 30-degree rostral oblique projection needs to be added to the bisecting angle technique to permit adequate visualization of the mesiobuccal and palatal roots. Critiquing Dental Radiographs Various organizations including the American Veterinary Dental College and the Academy of Veterinary Dentistry require dental radiographs for evaluation. Striving to follow these established guidelines will produce meaningful diagnostic films. These guidelines which have been previously published can be used as a guide to assist in self-evaluation of radiographs.3
Proper evaluation of feline teeth with odontoclastic resorptive lesions can help determine the appropriate treatment option including either routine extraction or crown amputation with intention root retention. When retained roots are identified with dental radiography a decision to retrieve or retain these roots must be made. If the retained roots are an incidental finding in a patient that is asymptomatic and there is no evidence of periapical or apical lysis around the retained root tip and the root is covered by normal gingiva that is epithelized than no treatment is recommended. However, if the patient is symptomatic, there is an area of granulation tissue over the retained root tip or radiographically there is evidence of periapical or apical lysis than removal of the root is recommended. Dental radiographs can be used to assess bone loss secondary to periodontal disease and help determine the most appropriate treatment plan. In cases in which there is greater than either 50-75% attachment loss or bone loss to the apex of a single root of a multi-rooted tooth is revealed on the dental radiographs, extraction is generally recommended. Dental radiography can be used to evaluate for the presence of endodontic disease Abnormal radiographic findings associated with endodontic disease include: periapical lysis, apical lysis, large endodontic systems secondary to failure in normal development or resorption, radiographic loss of tooth structure to the pulp canal and secondary destruction of the periodontium. Periapical lysis appears as a dark halo around the apex of the roots caused by lysis of the bone around the apex of the tooth associated with endodontic disease. Apical lysis is lysis of the apex or tip of the root itself. Apical lysis is associated with chronic endodontic disease. It is important to recognize the presence of apical lysis since apical lysis precludes the performance of conventional root canal therapy alone and necessitates the performance of surgical endodontic therapy in combination with conventional endodontic therapy or exodontia. Large or asymmetrical endodontic systems may be secondary to failure in normal development from early pulpal death from endodontic disease or may be secondary to internal resorption from pulp damage. The canals of affected teeth may be larger then the contralateral canals or larger than the canals of adjacent teeth or may be asymmetrical within a solitary affected tooth. Chronic endodontic disease can result in secondary destruction of periodontal structures along the root of a tooth with pulpal necrosis. Dental radiography is recommended in the evaluation of missing teeth. In puppies with missing deciduous teeth a dental radiograph may be taken to determine if a permanent tooth bud is present. Early determination of the absence of a permanent tooth bud will help breeders determine if a dog is either show or pet quality. Dental radiography can also reveal the location of teeth that have been misplaced following trauma. Teeth that appear malformed require dental radiographs to help determine the presence of endodontic disease. Developmental abnormalities such as dens-in-dente in which the enamel is enfolded may result in secondary endodontic disease. This condition appears to most frequently affect the lower 1st molar in the dog and often occurs bilaterally. These teeth appear to have an increased radiodensity in the crown, convergence of the roots, large pulp canals and the presence of periapical lysis. Osteomyelitis may be detected radiographically. Osteomyelitis may be secondary to severe periodontal disease, endodontic disease or trauma. Osteomyelitis may appear as an increased bony density with loss of detail and periosteal reaction. Osteomyelitis should be treated by removal of diseased teeth and bony sequestra, and appropriate long term antibiotic therapy. Radiographs should be taken in animals with multiple loose teeth in one region of the oral cavity. Severe boney lysis and displacement of teeth is suggestive of a malignant tumor. Biopsy of these lesions is required for a definitive diagnosis and for appropriate treatment planning. Metabolic bone diseases, such as renal secondary hyperparathyroidism can be evaluated with dental radiographs. The initial radiographic finding associated with hyperparathyroidism is loss of the lamina dura which is the cortical plate of the alveolus that surrounds the tooth roots. As the disease progresses there is a loss of density of trabecular and cortical bone. Dental radiographs are essential in the diagnosis of dentigerous cysts. When oral examination of dental patients reveals a soft, fluid filled gingival swelling in the region of a missing tooth a dental radiograph is recommended. Radiographs may reveal the presence of a dentigerous cyst which appears as a smooth-bordered radiolucent cavity typically adjacent to the cementoenamel junction of the unerupted, misplaced tooth. Dental radiographs are important in the perioperative management of jaw fractures. Preoperative radiographs will assist in the evaluation of the fracture site, determine the location of tooth roots in and around the fracture site and assist the selection of appropriate treatment options. Dental radiographs are also essential in the postoperative evaluation of fracture fixation and reduction and assessment of proper healing of jaw fractures. Summary Dental radiography is an essential component in the daily delivery of high quality dental care for dogs and cats. Recently many state-of-the-art veterinary practices have switched over to digital dental radiography because of the speed and ease in which these images can be produced and evaluated. The real value in taking digital dental radiographs is improved patient care while at the same time providing a profit center for the hospital. The advantages of digital dental radiography far outweigh the disadvantages of this new technology. With proper orientation and training in the use of digital dental radiographic units this new technology can become an integral part of small animal veterinary. Following an appropriate training period veterinarians and veterinary technicians will be able to obtain high quality dental images which will result in the recognition of more lesions which can then be appropriately treated. References
Interactive Oral Pathology Self-Assessment: Part I Dental problems occur frequently in dogs and cats. Periodontal disease is probably the most common disease affecting dogs and cat today.1 Additional dental diseases and oral lesions also occur frequently in dogs and cats. Because of the high prevalence of these diseases in companion animals it is particularly important for the veterinarian to be familiar with various types of dental and oral pathology. The purpose of this presentation is to provide veterinarians with the opportunity to evaluate their working knowledge of canine and feline dentistry in an interactive format. This interactive session will include recognition of dental and oral lesions and a discussion of appropriate diagnostic procedures and treatment planning of various dental and oral lesions will follow. Variation in Number of Teeth It is important for veterinarians to know the dental formula for both the dog and cat so that any abnormalities can be appropriately recorded on the dental chart and treated appropriately. The dental formulas of dogs and cats are:
Oligodontia or decreased number of teeth is more common in dogs than cats. Although oligodontia is not a serious medical problem it can be a problem for breeders since it is considered a genetic imperfection. Puppies with missing deciduous teeth will also be missing the same adult teeth. Supernumerary teeth or extra teeth may result in crowding and malalignment of teeth predisposing to the development of periodontal disease. The mandibular fourth premolars appear to be the most common supernumerary teeth in the cat. Various teeth in the dog may be supernumerary. Supernumerary teeth that are not causing crowding or malalignment of teeth require no treatment. Supernumerary teeth that result in crowding should be extracted. Prior to extraction supernumerary teeth should be radiographed to evaluate their root structure. Retained Deciduous Teeth Retention of deciduous teeth can occur in both dogs and cats. In cats the canine teeth are most frequently retained. In dogs the canine teeth are also the most frequently retained teeth, however, the incisor and premolars may also be retained. Retained deciduous teeth should be extracted as soon as they are diagnosed so that permanent teeth may erupt into their normal positions. When retained deciduous teeth are not removed, permanent teeth are deflected lingually, except maxillary canine teeth, which are deflected rostrally. Deciduous teeth are smaller than their permanent counterparts. When difficulty is encountered in determining which tooth is deciduous and which tooth is permanent a dental radiograph should be taken. The root of the permanent tooth in a 6-month-old animal will have a wide pulp canal with thin dentinal walls and an open apex compared to the deciduous teeth which will have a much thinner but more developed root. Oronasal Fistulas Secondary to Periodontal Disease Animals with oronasal fistulas secondary to periodontal disease may present with a history of sneezing and mucopurulent or hemorrhagic nasal discharge. The most common location of oronasal fistulas in the dog and cat is the palatal aspect of the maxillary canine tooth. Other teeth that can potentially cause oronasal fistulas are the maxillary incisors, premolars and molars. Confirmation of oronasal fistulas is made with a periodontal probe. All teeth should be carefully probed to detect the presence of oronasal fistulas in animals presented with nasal discharge. When placed in an oronasal fistula the periodontal probe will drop into the nasal cavity and frequently blood may be seen dripping from the ipsilateral nostril if the nose in placed in a dependent position. Teeth associated with oronasal fistulas should be extracted and the oronasal fistula should be repaired with a mucoperiosteal flap. Furcation Exposure The furcation is the area where the roots of multi-rooted teeth meet. In advanced cases of periodontitis the furcation may be exposed. The severity of furcation lesions has been classified into three categories. Class 1 lesions have a defect between the roots that can be felt with a periodontal probe which is less than 3 mm deep. Class 2 lesions have a defect in which the periodontal probe can pass horizontally into the furcation for more than 3 mm but not all the way through the furcation. Class 3 furcation exposure is when the periodontal probe can be passed all the way through the furcation. Facial Swelling and Draining Tracts Associated with Periodontitis Periodontitis can cause facial swelling and draining tracts. A periodontal probe and dental radiographs can help confirm the diagnosis and appropriate treatment plan. A periodontal probe properly utilized can accurately assess attachment loss associated with periodontal disease and help localize a periodontally diseased tooth that may be the cause of facial swelling or draining tracts. The periodontal probe is placed perpendicular to the gingival margin and gently inserted parallel to the long axis of the tooth to the bottom of the sulcus or pocket. The probe is "walked" around the entire wall of the tooth, measuring the depth of the sulcus or pocket in at least six places around the tooth. In some cases purulent discharge may be released from the periodontal pocket upon probing in animals with facial swelling. In general, periodontally diseased teeth that are causing facial swelling and draining tracts should be extracted. Perioperative antibiotics are recommended in animals with moderate to severe periodontitis, patients with painful oral ulcerations, animals who do not receive any home oral hygiene, those with systemic disease that may be worsened by bacteremia (turbulent blood flow caused by heart valve lesions or chronic renal failure), and patients undergoing concurrent clean or clean-contaminated surgical procedures.2 An excellent antimicrobial for clinical use in dogs with periodontal disease is amoxicillin-clavulanic acid (Clavamox: Pfizer).3 The length of time recommended for the perioperative administration of antimicrobials varies from 2 to 10 days depending on the severity of periodontal disease. Perioperative antibiotics should be administered so that a therapeutic blood level is obtained prior to induction of the bacteremia caused by the dental therapy.2 Analgesics are recommended perioperatively in the treatment of periodontal disease and other painful dental and oral diseases. Injectable premedicants such as medetomidine, butorphanol or morphine can be administered preoperatively to provide preemptive analgesia. Regional nerve blocks such as the infraorbital or metal nerve blocks are also effective in providing analgesia for painful dental procedures. Additionally, carprofen (Rimadyl: Pfizer) a non-narcotic, nonsteroidal, anti-inflammatory drug can be administered perioperatively in dogs to relieve pain and inflammation associated with dental procedures. Carprofen may be started one day prior to the dental procedure and continued as needed postoperatively. This drug is not recommended in dogs with gastrointestinal, renal or hepatic problems. The dose is 2mg/kg orally every 12 hours. Feline Perialveolar Osteitis A severe firm swelling around the root of the maxillary canine tooth may occur in middle-aged and geriatric cats. This bulbous maxillary canine tooth perialveolar swelling often occurs bilaterally and may be associated with periodontal or endodontic disease and should not be mistaken for neoplasia. Periodontal probing and dental exploration of the affected maxillary canine teeth often reveals a deep periodontal pocket or chronic pulpal exposure. A dental radiograph may reveal a loss of trabecular bone pattern around the roots of affected maxillary canine teeth with a thin line of sclerotic bone surrounding the periradicular bone loss. Fractured Teeth Fractured teeth usually result from external trauma. In cats, the tooth most frequently fractured because of trauma is the canine tooth. Fractured canine teeth in cats often result in pulpal exposure because of the extension of the pulp canal into the coronal tip of the canine tooth in felines. Pulpal exposure is confirmed if a fine dental explorer penetrates into the canal. The teeth most frequently fractured in the dog are the canine teeth, incisors, and the maxillary fourth premolars, however, any tooth may be fractured. Following pulpal exposure the following sequence of events may occur: Pulpal exposure?Bacterial pulpitis?Pulp necrosis?Apical granuloma?Periapical abscess?Acute alveolar periodontitis?Osteomyelitis?Sepsis Radiographic evidence of chronic endodontic disease or pulpal necrosis include:
Dental Attrition and Dental Abrasion Dental attrition is the gradual and regular loss of tooth substance resulting from normal mastication. Excessive wear caused by malocclusion resulting is tooth-to-tooth contact is called pathologic attrition. Dental abrasion is the mechanical wear of teeth caused by mechanical wear other than by normal mastication or tooth-to-tooth contact such as wear caused by chewing rocks, cage bars, or wire. In cases of dental attrition the pulp responds to rapid wear by laying down tertiary or reparative dentin, which is visible as a dark brown spot on the affected tooth. The dark brown spot is solid and cannot be entered with a dental explorer. No therapy is usually required in these cases. Occasionally, very rapid dental attrition can result in pulpal exposure. These cases require endodontic therapy or extraction. Cage-Biter Syndrome Cage-biter syndrome can be seen in dogs who chronically chew on their cage bars. The unique pattern of dental wear associated with cage-biter syndrome includes dental wear on the distal aspect of the canine teeth. Dogs affected by severe wear on the distal aspect of their canine teeth may be affected with dentinal hypersensitivity, endodontic disease, and crown weakening resulting in dental fractures. Dental radiographs should be taken of teeth affected with cage-biter syndrome to help rule out the presence of endodontic disease. If endodontic disease is present affected teeth should be endodontically treated or extracted. Full or three-quarter prosthetic crowns can be placed on teeth affected with cage-biter syndrome. A three-quarter crown is preferred in teeth that are not endodontically treated so that if endodontic treatment is required at a later date the ideal access site can be easily created without damaging the prosthetic crown. Feline Odontoclastic Resorptive Lesions Feline odontoclastic resorptive lesions are one of the most common dental lesions in cats. A recent report reviewing 10 independent surveys of odontoclastic resorptive lesions revealed that 20 to 67 per cent of all cats have 1 or more lesions with a mean of 2.3 to 4.1 lesions per affected cat.4 Feline odontoclastic resorptive lesions are characterized by a clinically or radiographically evident defect in the enamel, dentin and/or cementum. These lesions may be hidden from view by plaque, dental calculus or inflamed gingival tissue. Clinically, resorptive lesions are areas in which tooth substance is missing and may be seen as an actual absence of tooth substance or the missing hard tooth tissue is replaced with granulation tissue. A dental explorer is gently moved over the surface of the tooth within the gingival sulcus to detect these lesions and when a resorptive lesion is encountered it will fall into the irregular area of resorption and in some cases the lesion becomes quite apparent when an undercut area of cementum and dentin is penetrated, producing an overhang of enamel. These lesions should be radiographed to determine the full extent of the lesions. Discoloration of Teeth Hemorrhage or necrosis of the pulp results in lysis of red blood cells. This results in hemoglobin breaking down into pigments which penetrate into the dentinal tubules and result in a variety of discolorations of the affected tooth. The color of the traumatized crown may vary from pink-red to blue-gray or dark gray. When intrapulpal hemorrhage is minor the pulp may remain vital and the blood pigment may be resorbed and the crown discoloration may be temporary.5 In a recent clinical study reviewing the incidence of localized intrinsic straining of teeth due to pulpitis and pulp necrosis in dogs, it was found that a distinct majority of teeth (92.2%) with pink/grey/tan crown discoloration had either partial or total pulp necrosis based on visual examination of the pulp during root canal therapy or exploratory pulpotomy.6 However, radiographic signs of endodontic disease were not present in 42.4% of affected teeth indicating that dental radiographs should not be relied upon to indicate pulp vitality in discolored teeth.6 This study recommended that all discolored teeth receive either endodontic or exodontic therapy. An obvious concern for practicing this treatment rationale routinely would be that vital, discolored teeth may undergo unnecessary endodontic therapy or extraction. However, the risk of unnecessary dental treatment would be acceptably low (<10%) in exchange for the assurance of potential pain alleviation.6 Tetracycline Staining Yellowish discoloration of teeth may be caused by tetracycline staining. When tetracycline is administered during pregnancy and the development of deciduous and permanent teeth, the tetracycline will combine with the calcium in the teeth to form a tetracycline-calcium orthophosphate complex that results in a yellowish discoloration of the teeth.7 To prevent tetracycline staining of teeth avoid administering tetracycline to pregnant and young animals. Enamel Hypoplasia Enamel hypolasia is defined as an incomplete or defective formation of the organic enamel component.8 Enamel hypoplasia is caused by disruption of the ameloblasts during the first several months of life while the teeth are developing which may be associated with periods of high fever, infections (especially canine distemper), nutritional deficiencies, disturbances of the metabolism, and systemic disorders.8 Shortly after eruption, the soft, brittle enamel peels off exposing the underlying dentin which is soon stained yellowish-brown by extrinsic factors. In cases of enamel hypoplasia, there exists a deficiency in the thickness of the enamel: the defects in the enamel can be limited to a circumscribed area or be recognized as a single narrow zone of smooth or pitted hypoplasia.8 Disturbance in enamel formation over a longer period of time results in a more generalized distribution of lesions. When enamel hypoplasia is limited to a solitary tooth the most likely cause is trauma. Diffuse enamel hypoplasia is treated with routine cleaning and home care while solitary teeth may be treated with composite restorations to achieve an esthetic result or alternatively a metal crown can be applied to the affected tooth. Interactive Oral Pathology Self-Assessment: Part II Dentigerous Cysts Dentigerous cysts occur infrequently in dogs, however, the diagnosis of dentigerous cysts should be a primary consideration in young dogs presenting with oral swellings in edentulous areas. Definitive diagnosis of a dentigerous cyst is based on history, physical examination, dental radiography, and histopathologic examination. Dentigerous cysts arise from the cellular components of the developing dental follicle. The cyst contains one or more embedded teeth and usually surrounds the coronal aspect of the tooth. As the tooth bud continues to develop but fails to erupt, the cyst becomes filled with fluid. Fluid pressure within the cyst results in a smooth-bordered radiolucent cavity typically adjacent to the cementoenamel junction as viewed radiographically. The treatment of a dentigerous cyst usually involves surgical extraction of the affected tooth and thorough removal of the entire epithelial lining of the cyst wall which is submitted for histopathologic examination. Complete removal of the tooth and the cystic epithelium is curative. Gemination Gemination of teeth is a disorder in which the developing tooth bud attempts to split but fails to do so completely, resulting in duplication of part of the tooth but not complete twinning. Gemination of teeth is usually manifested by two crowns, each with a separate pulp chamber merging into a common root canal system which can be demonstrated radiographically. In the cat, gemination appears to most frequently affect the maxillary 3rd and mandibular 4th premolars. In dogs gemination of single incisors may occur. When gemination occurs in premolar teeth they often have two normal sized roots one mesial and one distal and one large common centrally located root which can be demonstrated radiographically. When gemination occurs in incisor teeth there are two incompletely separated crowns and a single root canal. Gemination is usually an incidental finding on oral examination but is clinically significant when extraction is necessary because of the abnormal root structure associated with these teeth. A dental radiograph prior to extraction can help determine the location of the roots in teeth exhibiting gemination so that the teeth may be sectioned appropriately. Supernumerary roots Supernumerary roots are generally incidental findings on oral examination and generally occur as extra roots in teeth that normally have only two roots. It is important to know both the normal and abnormal root structure of teeth in both the dog and the cat so that teeth can be accurately sectioned prior to extraction. Dental radiographs can help localize supernumerary roots. The normal number of roots in canine and feline teeth follows.
Enameloma or Enamel Pearl or Dens-in-Dente An enameloma or enamel pearl is a developmental anomaly in which there is a small nodule of enamel below the cementoenamel junction that is usually located at the bifurcation on the molar teeth. Developmental anomalies such as dens-in-dente may be bilaterally symmetrical in some patients and may predispose the anomalous teeth to endodontic pathology. When developmental irregularities in the crown are recognized during routine oral examination a dental radiograph of the tooth and the ipsilateral tooth should be taken to evaluate for the presence of endodontic pathology. Dental Caries Dental caries is demineralization of the tooth and results in subsequent loss of tooth structure. Early dental caries may appear as a dark brown spot and have a sticky or slightly soft feel when probed with a dental explorer. Once dental caries perforates the enamel, the caries can progress rapidly in the dentin, destroying the tooth and eventually resulting in pulpitis and pain. This may be followed by pulp necrosis and periapical infection. The teeth most commonly affected in dogs with dental caries are the maxillary first molar, and the mandibular first and second molars. When dental caries occurs in the dog the lesions are often multiple and advanced. Dental radiographs should be taken of teeth with dental caries to rule out any associated endodontic pathology. Treatment of dental caries includes extraction or restoration of affected teeth. Lymphocytic Plasmacytic Stomatitis Cats with lymphocytic plasmacytic stomatitis (LPS) typically present with a history of halitosis, ptyalism, dysphagia, inappetence and weight loss. Oral examination reveals a hyperemic, proliferative ulcerative mucosa with a raspberry red, cobblestone appearance. These lesions may be primarily around the dentition but may extend onto the palatoglossal folds and fauces. The etiology is unknown. Histologically, this condition is characterized by infiltration of affected tissue with large numbers of lymphocytes and plasmacytes. The serum proteins are high because of severe elevations in the globulins. Cats with lymphocytic plasmacytic stomatitis should be tested for feline leukemia virus and feline immunodeficiency virus, although many test negative. Cats with LPS often lack a permanent response to conventional oral hygiene, antibiotics, anti-inflammatory drugs, and immunomodulators. Refractory cases frequently necessitate extraction of at least all the premolars and molars and in some cases extraction of the entire dentition including removal of all root tips and debridement of reactive bone is required. Sublingual and Buccal Mucosal Hyperplasia (Gum-Chewers Lesions) Sublingual and buccal mucosal areas of excessively loose mucosal folds that are indurated and hyperplastic secondary to repeated self-inflicted trauma have also been described as "gum-chewers lesions" because the behavior of dogs with these lesions may mimic that of a person aggressively chewing gum. These lesions may become quite large and may be painful when they are repeatedly traumatized by chewing on the lesions with the molar teeth. When these lesions become ulcerated and become a source of pain for the patient, surgical excision is recommendcd. The resected tissue should be submitted for histopathologic evaluation to rule out the presence of neoplasia. Feline Mandibular Swelling Feline mandibular swelling is not readily recognized become of the ventral location of the mandible. Without careful palpation of the ventral aspect of the mandible, mandibular swelling may not be detected. Feline mandibular swelling may be benign or malignant. The most common cause of benign mandibular swelling in cats is osteomyelitis secondary to retained odontoclastic resorptive tooth roots and less frequently secondary to periodontal disease and endodontic disease. The most common cause of malignant feline mandibular swelling is squamous cell carcinoma and less frequently fibrosarcoma, lymphosarcoma, and osteosarcoma. Thorough oral examination, dental radiography, and intraoral incisional biopsy will help provide a definitive diagnosis. Base-Narrow Mandibular Canine Teeth in Dogs Base-narrow mandibular canine teeth in dogs often results in traumatic occlusion of the lower canine teeth with the soft tissues of the hard palate. This malocclusion can result from an extreme retrognathic mandible (more caudal than normal location of the mandible), brachygnathic mandible, excessive anisognathism (uneven jaw size), or retained deciduous canines that have directed the lower canines into a more lingual than normal base narrow position.9 Since all of these conditions are considered to be genetically linked breeding of these animals is not recommended. Some cases of base-narrow mandibular canine teeth may be corrected by encouraging dogs to play and chew on a large ball positioned in the front of the mouth. Malocclusions that are not successfully treated utilizing this simple technique may be corrected with direct bite planes. Bilateral inclined planes are constructed between the maxillary canines and third incisors so that the tip of the mandibular canine teeth hit the inclined planes in such a way as to redirect the mandibular canine teeth into a more normal location thereby eliminating the traumatic malocclusion. The time required for tooth movement utilizing this technique is usually between 2 and 6 weeks. Management of Tooth Luxations and Avulsions Tooth luxations are the displacement or partial displacement of teeth from their alveoli. Dental avulsions are the loss of teeth from their alveoli. Teeth accidentally avulsed or luxated from their alveoli by trauma should be reimplanted or repositioned as soon as possible, ideally within 30 minutes. Teeth that are luxated or avulsed because of advanced periodontal disease should not be reimplanted. Until reimplantation of traumatically avulsed teeth is possible, affected teeth may be briefly stored in saliva or milk. Following reimplantation the tooth is held in position with a figure-of-eight wire and an interdental splint. The prognosis for luxated teeth is better than avulsed teeth because of less damage to the periodontal tissues. Endodontic therapy is recommended 2 weeks after correction of luxations and avulsions. In addition, these teeth should be stabilized with an interdental splint for approximately 6 weeks. Oral Tumors Oral tumors occur frequently in dogs and cats. Oral tumors account for approximately 6% of all malignant tumors in dogs with malignant cancer of the mouth and pharynx occurring 2.6 times more frequently in dogs than in cats.10 Oral tumors may be benign or malignant. Unfortunately, diagnosis of oral malignancies frequently occurs when the tumor is quite advanced, necessitating more extensive treatment. Thorough oral examination during routine physical examinations and during dental procedures can permit early detection of oral tumors providing patients with a better prognosis. Early diagnosis of oral tumors, appropriate staging, wide surgical resection and alternative treatment modalities can improve survival time. When an oral mass is detected during a routine dental procedure a dental radiograph should be taken to determine the presence of underlying boney lysis which may be seen with malignant oral tumors. The mass should be biopsied to determine whether or not the tumor is benign or malignant. Biopsy of large oral masses must be deep, because superficial biopsies may reveal only inflammation or gingival hyperplasia. A deep wedge biopsy or a deep Tru-cut is recommended. The use of electrosurgery for obtaining oral tumor biopsies is not recommended. Non-neoplastic reactive lesions that occur as a result of chronic low-grade irritation such as focal fibrous gingival hyperplasia and pyogenic granulomas occur at the gingival margin and are treated with a gingivectomy and treatment of the underlying cause of the inflammation which is most frequently periodontal disease. Malignant oral tumors require more aggressive surgical treatment to help prevent local recurrence including various partial mandibulectomy and maxillectomy procedures depending on the location of the oral tumor. References:
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