Cats have two sets of teeth, the deciduous and permanent dentitions. Deciduous incisors erupt at 2–3 weeks, canines at 3–4 weeks, and premolars at 3–6 weeks of age. There should be 26 deciduous teeth. Permanent incisors erupt at 3–4 months, canines at 4–5 months, premolars at 4–6 months, and molars at 4–5 months of age. There should be 30 permanent teeth. At 7 months of age, the young cat should have 30 fully erupted permanent teeth in place (Table 24.1).

There are four specific types of teeth, each serving a distinct purpose. The incisors are designed to cut, prehend, and groom. The canines are used to penetrate and grasp prey or food and also function as defensive weapons in protection. The cheek teeth (premolars and molars) assist in the ability to hold and carry, in addition to breaking and tearing of food into smaller pieces in preparation for digestion. The so-called carnassials refer to the maxillary fourth premolar and mandibular first molar teeth, which serve a shearing function in carnivores.²

The total number of teeth in the cat is greatly decreased compared to the dog, and the shapes of crowns of feline teeth reflect the function of a true carnivore.3 Domestic cats have 26 deciduous and 30 permanent teeth (Table 24.2). Using the modified Triadan tooth numbering system, each jaw quadrant is numbered as follows: right maxillary quadrant 100 (500 when referring to deciduous teeth), left maxillary quadrant 200 (600 when referring to deciduous teeth), left mandibular quadrant 300 (700 when referring to deciduous teeth), and right mandibular quadrant 400 (800 when referring to deciduous teeth).²

Beginning with 01 for the first incisor (the one closest to the midline), teeth are consecutively numbered from mesial (the surface of the tooth that faces the midline of the dental arch) to distal (the surface of the tooth that faces away from the midline of the dental arch). Several premolars and molars have been evolutionarily lost in the permanent dentition of the cat. The canine (04) and the first molar (09) are present as reference teeth to allow counting forward or backward when numbering teeth. The permanent maxillary first (05) premolar and the permanent mandibular first (05) and second (06) premolars are absent in the cat. Since the maxillary fourth premolar (08) and mandibular first molar (09) are the largest cheek teeth of the upper and lower jaws, counting forward identifies the premolars between the maxillary canine and fourth premolar as the maxillary second and third premolars (teeth 06 and 07). Similarly, the premolars between the mandibular canine and first molar are identified as the mandibular third and fourth premolars (teeth 07 and 08).²

Taking the quadrant and tooth number into consideration, three numbers are used to identify a specific tooth. For example, the permanent right maxillary canine is tooth 104. The permanent right maxillary fourth premolar is tooth 108. The permanent left maxillary second premolar is tooth 206. The permanent left mandibular third and fourth premolars are teeth 307 and 308. The permanent right mandibular first molar is tooth 409 (Fig. 24.1). The deciduous right maxillary canine is tooth 504. The deciduous right mandibular fourth premolar is tooth 808 (Fig. 24.2).

The tooth consists of a crown and one or more roots. Enamel (with >95% mineralization, it is the hardest tissue of the body) covers the crown, and cementum covers the root(s). The borderline between the anatomic crown and root(s) is the cementoenamel junction.4 The incisors and canine teeth have one root. The maxillary second premolars and first molars have two roots which are often fused to each other, giving the appearance of only one root.⁵ The mandibular third and fourth premolars and first molars and the maxillary third premolars have two roots. The maxillary fourth premolar has three roots. The furcation is where two or more roots meet at the crown.²

Dentin makes up the bulk of the adult tooth. It is ~70% mineralized, porous, and consists of thousands of dentinal tubules per square millimeter radiating outward from the pulp to the enamel in the crown and cementum in the root.³ Odontoblasts line the periphery of the pulp cavity and produce dentin which – in a vital tooth – is laid down throughout life. Dentinal tubules contain cytoplasmic processes of odontoblasts, fluid, and nerves extending from the pulp. Tooth pain may result from fluid movement and nerve stimulation in the area of exposed tubules. Odontoblasts adjacent to exposed dentinal tubules may respond by producing tertiary dentin to halt the progression of an external insult.²

The pulp cavity consists of the pulp chamber in the crown and the root canal(s) in the root(s) of the tooth. It contains the pulp which is made up of undifferentiated mesenchymal cells, fibroblasts, odontoblasts, blood and lymph vessels, and nerves.³ Odontoblasts line the inside of the pulp cavity at the periphery of the pulp, initially producing nonmineralized predentin which later becomes mineralized dentin. Unlike human teeth that have only one apical foramen, the pulp of cat teeth connects with periapical tissues through several foramina in the root apex (forming the apical delta). Secondary, accessory, lateral, and furcation canals also may connect pulp tissue with the periodontal ligament.⁶ Therefore, entrance into the pulp cavity can be through exposed dentinal tubules, direct pulp exposure, and apical and non-apical ramifications.

The tooth “grows” towards the inside. The dentin becomes continually thicker in a vital tooth. Dentin apposition along the inside of the pulp cavity continues throughout life, unless irreversible pulpitis or pulp necrosis occurs. Therefore, teeth of young adult cats have a fairly wide pulp cavity (Fig. 24.3). In older cats, the pulp cavity of teeth with vital pulps is usually very narrow (Fig. 24.4). The narrower the pulp cavity, the thicker are the dentinal walls, and thus the stronger and more aged is the tooth.

The periodontium is a functional unit and consists of the gingiva, periodontal ligament, cementum, and alveolar bone.3 The gingiva surrounds the tooth like a collar and is firmly attached to the alveolar bone and cervical portion of the tooth. The most coronal edge of the gingiva is the gingival margin. A normal space between the tooth and most coronal gingiva is called the gingival sulcus, which should not be deeper than 0.5 mm in cats. The periodontal ligament acts as a shock absorber and attaches the tooth to the alveolar bone by means of Sharpey’s fibers. Some fibers connect adjacent teeth by traveling through or coronal to the alveolar septum. Radiographically, the periodontal ligament space appears as a dark line surrounding the root.

The cementum covers the root(s) and is produced by cementoblasts. It is similar in mineral composition and histological appearance to bone. Cementum width increases with age.² An excessive production of cementum (hypercementosis) is often seen in cat teeth, most commonly at the apical portion of the root. Alveolar bone surrounds the alveolar socket. An increased radiodensity of alveolar bone is visible adjacent to the periodontal ligament space, referred to as the lamina dura, which is an extension of cortical bone into the alveolus. The most coronal edge of the alveolar bone is the alveolar margin.² Alveolar bone is constantly remodeling in response to use and the forces placed upon it.

Oral mucosa other than gingiva includes the very flexible and elastic alveolar mucosa, which faces the alveolar bone and is separated from the gingiva by the mucogingival junction, the labial and buccal mucosae, which face the inside of the lip and cheek, the loose sublingual mucosa, the mucosa covering the dorsal and ventral tongue surfaces, the mucosa of the hard palate, which is firmly attached to underlying maxillae and palatine bones, and the mucosa of the soft palate.2 The oral mucosa is separated from the skin by the mucocutaneous junction (Fig. 24.5).

Most cats are mesaticephalic, referring to having a head of medium proportions. Brachycephalic cats have short, wide heads such as the Persian, and such head types often are associated with dental malformations.7 Dolichocephalic cats have long, narrow heads, such as the Siamese. The upper jaw and the face consist of the paired incisive bones, maxillae, palatine, nasal, zygomatic and temporal bones and the unpaired vomer bone. The incisive bones carry the maxillary incisor teeth, and the maxillae carry the maxillary canines, premolars, and molars. The infraorbital canal (containing the infraorbital artery, vein and nerve) penetrates the maxillary bone in the area of the fourth premolar and molar teeth.²

The lower jaw consists of the paired mandibular bones. The ventral third of each mandible includes the mandibular canal, which contains the inferior alveolar artery, vein and nerve. Right and left mandibles are separated rostrally by a fibrocartilaginous synchondrosis (mandibular symphysis) and carry all mandibular teeth. The temporomandibular joint is formed by the condylar process of the mandible and the mandibular fossa and retroarticular process of the temporal bone (Fig. 24.6). A thin, fibrocartilaginous disc lies between the hyaline cartilage-covered articular surfaces. A thick band of fibrous tissue on the lateral aspect of the joint capsule forms the lateral ligament, which tightens when the jaw opens.²

The masticatory musculature includes the masseter, temporal and pterygoid (medial and lateral), which close the mouth, and the digastricus muscles, which open the mouth.3 The lips and cheeks of cats are “tighter” and their oral vestibules less spacious than in dogs, making their labial and buccal mucosae less available for closure of large intraoral wounds. The commissure is where the upper and lower lips meet. There are three important structures within the soft tissues of the cheek that run nearly parallel over the masseter muscle in a rostrocaudal direction: the dorsal and ventral buccal branches of the facial nerve, and the parotid duct traversing between the two nerves and opening into the mouth at the parotid papilla in the buccal mucosa near the maxillary fourth premolar.²

The primary palate is made up of the rostral upper lip and the most rostral hard palate. Most of the hard palate and the soft palate constitute the secondary palate. The hard palate mucosa is nonelastic and has several transverse ridges (palatine rugae) and depressions. On the midline rostral to the first palatine ruga and just caudal to the maxillary first incisor teeth is the incisive papilla, which should not be confused with an abnormal proliferative lesion (Fig. 24.7).³ The main blood supply to the hard palate mucosa is provided by the paired major palatine arteries which pass through the palatine canals and emerge at the major palatine foramina palatal to the level of the maxillary fourth premolar tooth about halfway towards the midline, from where it runs rostrally in the palatine sulcus to the palatine fissures.²

The lingual mucosa is thick and heavily cornified dorsally but thin and less cornified ventrally. The cat’s dorsal tongue surface is very rough, having firm papillae that point caudally (Fig. 24.8). The lingual frenulum, which is part of the sublingual mucosa whose submucosa contains the paired sublingual veins, connects the body of the tongue to the floor of the mouth. The sublingual caruncles are situated at the rostroventral aspect of the frenulum and contain the orifices of mandibular and sublingual gland ducts. The lingual artery is the major blood supply to the tongue.²

There are four pairs of major salivary glands in cats: the parotid gland surrounding the horizontal ear canal, the mandibular gland situated in Viborg’s triangle near the maxillary and linguofacial veins, the sublingual gland with its monostomatic part intimately attached to the mandibular gland and its polystomatic part located more rostrally between the mandible and the tongue, and the zygomatic gland located on the floor of the orbit and whose ducts open on the buccal mucosa near the maxillary first molar tooth.3 Scattered glandular tissue is present submucosally in the lips (ventral and dorsal buccal glands). A small lingual molar gland is situated caudolingually to each mandibular first molar tooth and should not be confused with an abnormal proliferative lesion.

There are three lymph centers in the head (parotid, mandibular, and retropharyngeal).2 The parotid lymph node is located at the rostral base of the ear. Several mandibular lymph nodes lie ventral to the angle of the jaw above and below the linguofacial vein. The medial retropharyngeal lymph node is an elongated, transversely compressed node and lies along the craniodorsal wall of the pharynx. The paired small palatine tonsil is attached to the lateral pharyngeal wall.

The maxillary artery provides blood supply to the upper jaw via infraorbital, palatine (major and minor), and sphenopalatine arteries. The inferior alveolar artery (running in the mandibular canal) is a branch of the maxillary artery and provides blood supply to the lower jaw. It exits at the caudal, middle, and rostral mental foramina to supply the lower lips. Veins often exist concurrently with arteries and empty via the maxillary and linguofacial veins into the external jugular vein.2

Rostral refers toward the tip of the nose, caudal refers toward the tail, ventral refers toward the lower jaw, and dorsal refers toward the top of the head or muzzle. Mesial is the surface of a tooth facing the midline of the dental arch, and distal is the surface of a tooth facing away from the midline of the dental arch. Labial is the surface of a tooth facing the lip, and buccal is the surface of a tooth facing the cheek. Lingual refers to the surface of mandibular teeth facing the tongue, and palatal refers to the surface of maxillary teeth facing the hard palate (Fig. 24.9). Occlusal refers to the surface of a tooth facing an opposing dental arch, coronal refers to a location or direction toward the crown of a tooth, and apical refers to a location or direction toward the apex of a tooth’s root. Subgingival refers to an area that is apical to the gingival margin, and supragingival refers to an area that is coronal to the gingival margin.²

Age, breed, and sequence of development of clinical signs often are useful indicators. A full patient history is essential and should include questions about appetite; eating and drinking patterns; prehending, chewing, and swallowing; preference for soft or hard food; behavioral idiosyncrasies; access to treats and toys; vomiting, diarrhea, and weight loss; coughing and sneezing; polydipsia and polyuria; scratching, head shaking; presence of rapid lower jaw motions; previous and current medications (and responsiveness to medications); the animal’s environment; and the type and frequency of home oral hygiene.8,9

The presence of halitosis, preferential chewing on one side of the mouth, inability or reluctance to open or close the mouth, dropping food from the mouth, drooling of saliva, inappetence, weight loss, sneezing, nasal discharge, pawing at the face, enophthalmos or exophthalmos, oral and maxillofacial swellings, pain on palpation of oral and maxillofacial tissues, atrophy of masticatory muscles, malocclusion, and other abnormal clinical signs should be assessed. It is often helpful for the examiner to watch the animal eat and drink if the owner reports any abnormal behavior during eating and drinking.⁸ The owner may also videotape abnormal behavior at home and share the recording with the clinician.

Halitosis may be caused by oral disease (such as periodontal disease, stomatitis, and neoplasia), nonoral diseases (such as uremia, respiratory, or gastrointestinal disease), and diet. Inappetence may result from pain associated with inflammation and ulceration in the oral cavity. This may progress to unwillingness or inability to drink, causing dehydration. Pawing at the mouth and rubbing the mouth on furnishings are indications of oral or facial pain. Drooling usually results from reluctance or inability to swallow rather than from increased salivary production. It also may be caused by reluctance or inability to close the mouth. Saliva may be blood-stained if an ulceration is present in the mouth. Dysphagia (difficulty in or pain on swallowing) may result from inflamed, ulcerated, or traumatized tissues that cause local pain or from obstruction to the mechanics of swallowing by a mass lesion, neurologic disease, or palate defects. Rapid lower jaw motions (“jaw chattering”) often indicate oral pain in cats with tooth resorption. Nasal discharge may be related to rhinitis, endodontic disease, neoplasia, or a palate defect.^8,9

The cat may be unable or unwilling to eat or chew on the side of the mouth that has a problem. Teeth on the affected side may then show increased plaque and calculus accumulation compared to the healthy side. Differential diagnoses for a cat not being able or unwilling to open the mouth include oral ulceration, temporomandibular joint ankylosis, maxillofacial fractures, tetanus, ocular disease, space-occupying retrobulbar lesion, ear disease, and neoplasia. Differential diagnoses for a cat not being able or unwilling to close the mouth include temporomandibular joint luxation or fracture of bones forming the joint, open-mouth jaw locking, maxillary and (bilateral) mandibular fractures, and neoplasia.⁸

The eyes, ears, nose, face, lips, jaws, masticatory muscles, lymph nodes, and salivary glands should be examined. Attention should be paid to the nostrils (have one nostril closed with a thumb while airflow from the other nostril is evaluated), any discharge from oral, nasal and ocular orifices and sinus tracts, facial lacerations, asymmetry and facial swellings, presence of exophthalmos or enophthalmos, ability to retropulse the eye globes (by gently pushing them into their orbits), and swelling or atrophy of masticatory muscles.9

The jaws, intermandibular tissues, zygomatic arches, and neck should be palpated for pain, asymmetry, discontinuity, crepitus, and emphysema. The range of mouth opening is assessed, which also provides information about abnormalities of the temporomandibular joints and muscles of mastication.⁸

The skin and mucocutaneous areas should be examined prior to opening the mouth. The labial and buccal mucosa is examined by lifting the animal’s upper and lower lips. The oral mucosa should be moist, intact, nonpainful on touch, and may be pigmented. The color, size, location, thickness, surface characteristics, and symmetry of any oral lesions should be noted.8 The incisors, canines, and most cheek teeth can already be evaluated without opening the mouth. Opening the mouth is greatly facilitated when the cat’s head is rotated dorsally. One hand holds the entire head (in the area of the zygomatic arches), and then rotates it dorsally. The other hand opens the mouth by pushing the lower jaw ventrally (Fig. 24.10). The ventral surface of the tongue and sublingual tissues can be inspected by gently inserting the thumb of the second hand into the intermandibular area. This raises the tongue. The hard palate can also be inspected.⁸ Obvious lesions such as fractured teeth, moderate to severe periodontal disease, stomatitis, and oral masses can often be identified in the conscious patient. However, sedation or general anesthesia is usually required for a thorough intraoral examination.

The two most important instruments for evaluation of dental and periodontal tissues are the dental explorer and periodontal probe (Fig. 24.11). The structural integrity of teeth is assessed with a dental explorer whose pointed tip can detect irregularities of the crown surface. It is also used to determine the presence of pulp exposure in a fractured tooth. The alveolar mucosa over the roots of the teeth should be inspected and palpated for the presence of swellings and sinus tracts (the latter are often located near the mucogingival junction), which may indicate endodontic disease or neoplasia.^8,9 The periodontal probe is invaluable for an accurate periodontal examination. The probe is gently inserted into the gingival sulcus, and measurements are obtained at several locations around the entire circumference of each tooth. The gingival sulcus of cat teeth should not be deeper than 0.5 mm. Greater measurements indicate the presence of a periodontal pocket or, in the case of gingival enlargement, a pseudopocket. Other periodontal parameters include plaque and calculus (tartar) accumulation, gingival index, gingival recession or enlargement, total attachment loss, tooth mobility, and missing teeth. Any other abnormalities should be recorded in the dental chart, such as persistent (retained) deciduous teeth, supernumerary teeth, dental or skeletal malocclusion, circumscribed ulcers, wide-spread oral inflammation, palate defects, oral masses, lacerations, and other signs of trauma.^8,9

Examination for systemic disease is important to assess anesthetic risk or to determine the possibility of dental and oral lesions being secondary to a systemic condition.8 Preanesthetic blood tests should include a complete blood count and biochemical profile. Blood typing and cross-matching may occasionally be indicated. Urinalysis and cardiac examination are performed as necessary. Cats with acute or chronic oral inflammation (beyond gingivitis) should be tested for feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), and, occasionally, for feline calicivirus (FCV) and feline herpesvirus-1 (FHV-1).

Dental radiographs should always be obtained prior to tooth extraction to assess alveolar bone health and variations in root anatomy and to determine the presence of dentoalveolar ankylosis or replacement resorption of roots that could complicate the extraction procedure. They are also essential during all steps of endodontic procedures, including assessment of treatment outcome at follow-up visits. In addition to dental-related conditions, most jaw pathology can be satisfactorily assessed with conventional or digital (direct or indirect) dental radiography and intraoral and extraoral imaging techniques.10–12

A dental radiography machine is required regardless of whether a conventional or digital system is used. In the case of conventional dental radiography, dental (nonscreen) films (e.g., sizes 0, 2, and 4; Fig. 24.12), a chairside film processor, developer and fixer solutions, and a view box are needed.^11,13–15 Digital radiography utilizes sensor pads or phosphor plates instead of films. Sensor pads are only available in sizes 0 and 2. They are rather thick and may be difficult to insert into the mouth of smaller patients (Fig. 24.13). The image obtained is directly transferred to a computer. Phosphor plates are available in a wider variety of sizes including size 4 which is very useful to evaluate diseases of the nasal cavity, orbit, zygomatic arch, mandibular ramus, temporomandibular joint, and tympanic bulla in cats (Fig. 24.14). Following exposure, they are run through a scanner which indirectly transfers the images to a computer. The digital system requires less radiation to produce an image, which may also be modified with software programs.¹⁶ Exposure time is often the only adjustment to be made and depends on the size of the patient and tissue thickness to be imaged.¹¹

All personal should leave the room while radiographs are exposed. If this is not possible, one should stand at least 6 feet from the radiographic cone and at a 90–135-degree angle to the tube head. Gauze may be utilized to hold the films in proper position within the mouth of an intubated cat. The parallel technique is used for imaging the mandibular molars, the caudal mandibular premolars, and the nasal cavity, with the film/pad/plate placed parallel to the tooth and the radiographic beam directed perpendicular (90 degrees) to the film/pad/plate and tooth (Fig. 24.15).¹⁴ The bisecting angle technique minimizes distortion when obtaining radiographs of all maxillary teeth and the mandibular canines, incisors, and rostral premolars (Fig. 24.16).¹⁷ The film/pad/plate is placed as close to the teeth as possible. The angle that is formed between the long axis of the teeth and the plane of the film/pad/plate is bisected by an imaginary line. The tube head is positioned perpendicular to this imaginary line. An extraoral technique has also been suggested for imaging the maxillary cheek teeth to avoid overlapping of the teeth with the zygomatic arch of the cat.^10,13,18

Dental radiographs should be viewed in labial mounting, which requires the processed film to be placed on the view box with the raised dot facing the viewer.11 It is determined whether the image is of the upper or lower jaw and of the left or right side. The only three-rooted teeth are the maxillary fourth premolars. The palatine fissure is also located in the upper jaw. The ventral mandibular cortex or mandibular canal is often visible on films of the lower jaw. Films of teeth of the left jaws are placed on the right side of the view box, and those of the right jaws on the left side of the view box. Each film should be rotated so that the crowns of the maxillary teeth face downward and those of the mandibular teeth face upward. The computer software of digital radiography systems will automatically perform these tasks.^11,16

The enamel, dentin, cementum (visible radiographically only when thickened), alveolar margin, periodontal ligament space, lamina dura, and pulp cavity are evaluated. The mandibular canal is visible as a radiolucent tubular structure in the mandible. Mental foramina and palatine fissures may sometimes be mistaken for periapical pathology.^10,11,13

Computed tomography is a useful imaging modality for the diagnosis and treatment planning of oral and maxillofacial trauma, neoplasia, and many other conditions.19,20 It is of great value for exploration of a large volume of soft and hard tissue in a significantly shorter examination time and at a much lower cost than magnetic resonance imaging. This is particularly important when a rapid diagnosis is needed for patients with head trauma or uncertain head pathology and for those that are less than optimal anesthesia candidates. Computed tomography is of great value for detection of hard tissues which is imperative when defining tumor margins and planning radical surgical excision. It also allows three-dimensional reconstruction, which facilitates understanding of the overall appearance of lesions, and can help guidance of a needle aspiration to establish a cytological diagnosis.

The patient is placed on the table in sternal recumbency with the head extended and secured in position and the forelimbs flexed caudally. Fluid lines and other extraneous structures are kept out of the gantry/field to avoid artifacts. Following a precontrast scan, an intravenous iodinated contrast medium is administered, and a postcontrast scan is performed. Pre- and post-contrast image series should be obtained of the entire head and cranial neck in an axial scanning mode, with slice thickness of 1 mm and interval of 2–3 mm for bone and slice thickness of 3 mm and interval of 3 mm for soft tissue. If lesions are in surgically inaccessible locations, a fine-needle aspirate can be obtained with an appropriate needle, which is inserted into the skin and advanced under subsequent computed tomography–guidance (scan-advance-scan) to the lesion.

Soft tissue is evaluated on soft tissue algorithm images, and the teeth, bones, and joints of the head are evaluated on bone algorithm images (Fig. 24.17). Window levels and widths are adjusted manually as needed. Maxillofacial soft tissue structures of interest include the masticatory muscles, salivary glands, soft tissue coverings of the nasal and oral cavity, soft palate, pharynx and larynx, and head and neck lymph nodes. These soft tissues can be evaluated for their size, precontrast tissue attenuation and shape of abnormal densities, and degree and distribution of contrast enhancement. Enlarged soft tissues are consistent with edema, inflammation, or neoplasia. Abnormally small soft tissue structures are indicative of atrophy, necrosis, or fibrosis. Precontrast tissue hypoattenuation indicates increased fluid content consistent with edema. Irregular contrast enhancement is indicative of areas of increased vascularity consistent with inflammation or neoplasia, and nonenhancing cores are suggestive of necrosis or abscess. Bones and joints of the head are evaluated for any evidence of periosteal reaction or periarticular new bone formation, fractures, osteolysis, deformity, masses, and joint pathology.²¹ The teeth are evaluated for structural defects, abnormal root canal widths, and changes to the periodontal attachment apparatus.

Gingivitis is reversible, affecting gingiva only (Fig. 24.23). The gingiva may detach from the tooth, creating a periodontal pocket, and a shift occurs in the gingival flora from a gram-positive aerobic to a gram-negative anaerobic spectrum.²⁸ Treatment of gingivitis is plaque control, and daily toothbrushing can resolve gingivitis. In adolescent cats, a particular form of gingivitis has been recognized. This so-called juvenile hyperplastic gingivitis occurs after eruption of the permanent dentition at about 6 to 8 months of age, with the inflamed gingiva being enlarged to a degree that it can cover the crowns of the teeth (Fig. 24.24). It is not known whether juvenile hyperplastic gingivitis is a precursor form of more severe oral inflammation and can progress to stomatitis in the adult cat. Gingival enlargement is also caused by administration of anticonvulsants, cyclosporine, and calcium channel blockers. Treatment of gingival hyperplasia involves resolving the cause and removal of excess gingiva. Because most cat teeth have less than 2 mm of attached gingiva, gingival surgery should be carefully executed and is often reserved for canine teeth and teeth with significant gingival enlargement.¹

Periodontitis is the more severe form of periodontal disease, affecting all periodontal tissues and resulting in attachment loss, gingival recession, furcation exposure, periodontal pocket formation, and alveolar bone loss (Fig. 24.25).^28,32 Bacterial infection of the pulp is possible in areas devoid of cementum and through apical and non-apical ramifications. Alveolar bone loss is usually irreversible, causing the tooth to become mobile and ultimately to exfoliate.³³ Similar to juvenile hyperplastic gingivitis, a so-called juvenile-onset periodontitis has been described in cats less than 1 year of age.¹ The teeth of such adolescent cats are often severely mobile on digital palpation and show most other clinical and radiographic signs associated with periodontitis.³²

Closed treatment may be enough when periodontal pocket depths do not exceed 2 mm in cats. Professional dental cleaning is performed with power scalers, followed by the use of hand scalers to remove residual calculus in pits, fissures, and developmental grooves of the crowns and hand curettes to clean and plane exposed root surfaces (Fig. 24.26). Prevention of hypothermia is of particular importance when water is used to cool power instruments or to rinse debris from the mouth.³⁴ Subgingival scaling (cleaning and planing of the root surface) is performed with hand curettes, which can also be used for gingival curettage that removes the inflamed and infected soft tissue lining of the periodontal pocket. Once scaling is completed, the tooth surfaces are polished with fine polishing paste and a rubber cup on a prophy angle that is attached to a low-speed handpiece. Debris and polishing paste are rinsed from the tooth surface with water from an air/water syringe.^28,33

Open treatment is usually indicated when pocket depths exceed 2 mm and is performed following reflection of a mucoperiosteal flap with or without vertical releasing incisions made into gingiva and alveolar mucosa.28 Osseous surgery and placement of implants are possible with this flap design.³⁵ The flap is sutured closed with synthetic absorbable monofilament material such as poliglecaprone-25.³³ Lateral sliding flaps and free gingival graft techniques are available for treatment of gingival clefts. Medical therapy includes the use of topical rinsing solutions (e.g., 0.2% chlorhexidine) or systemic antimicrobials (e.g., amoxicillin/clavulanic acid, clindamycin). Because of potential side effects and the possibility of bacterial resistance, systemic antimicrobials should only be used in selected cases to serve as an adjunct to local treatment.^36,37 Low-dose doxycycline gel may be inserted into cleaned periodontal pockets greater than 4 mm after root planing and gingival curettage.

Plaque control is a critical component of periodontal disease prevention and in the maintenance of treatment success.36,38,39 The owner is given instructions on daily tooth brushing with a soft bristled toothbrush and pet dentifrice.⁴⁰ In addition, oral hygiene is enhanced by the use of treats, diets, and products that meet preset criteria for effectiveness in mechanically and/or chemically controlling plaque or calculus deposition.^41–44 For a list of approved products please visit the website of the Veterinary Oral Health Council (http://vohc.org).

Feline teeth may appear clinically healthy, but they often show histological and radiographic changes in periodontal and dental tissues, such as periodontal ligament degeneration, hypercementosis, and hyperosteoidosis. Narrowing of the periodontal space may result in ankylotic fusion (dentoalveolar ankylosis) between the tooth and alveolar bone. These findings demonstrate events that occur prior to obvious tooth resorption and suggest that the very early lesion probably is noninflammatory in nature.49 Ankylosed roots are at risk of being incorporated into the normal bone remodeling process, resulting in gradual resorption of the root and replacement by bone (replacement resorption [type 2 lesion]) (Fig. 24.27).^46,47

Resorption of enamel may occur when root resorption has progressed coronally into the crown. The enamel may then become undermined or penetrated by the resorption process. When such lesions emerge at the gingival margin, they become exposed to oral bacteria, which results in formation of inflamed granulation tissue (Fig. 24.28). These defects are painful and bleed easily when probed with a dental instrument. One common feature of inflammatory root resorption (type 1 lesion) is that the alveolar bone adjacent to the tooth defect is also resorbed.^46,47 Mandibular third premolar and molar teeth are most commonly affected by tooth resorption, especially for type 1 lesions. Canine teeth are more likely to have type 2 lesions.⁵⁰

Several other peculiarities are noted in the permanent teeth of cats that could be associated with tooth resorption, including unusual thickening of alveolar bone (alveolar bone expansion) and abnormal extrusion of canine teeth (supereruption).46,47,51,52

Cats with tooth resorption were shown to have significantly lower urine specific gravity and significantly higher serum concentrations of 25-hydroxyvitamin D (25OHD), compared to cats without tooth resorption.48 These findings – together with the fact that multiple teeth are affected – indicate that tooth resorption in cats may have a systemic rather than a local cause. Cats are not able to produce vitamin D in skin,⁵³ and their minimum dietary vitamin D requirement may be low when compared with other species.⁵⁴ Commercial cat foods often contain vitamin D in excess of the maximal allowance.⁵⁵ Since a direct linear relationship exists between 25OHD serum concentrations and dietary intake of vitamin D,⁵⁶ cats with higher 25OHD serum concentrations must have ingested larger amounts of vitamin D or vitamin D metabolites. Significantly decreased urine specific gravity in cats with tooth resorption⁴⁸ also indicate that this condition might not just be a local oral disease but probably be associated with pathology in other areas of the body, such as abnormal mineralization of kidneys due to excessive dietary intake of vitamin D.^47,48 Studies have also demonstrated that the nuclear vitamin D receptor is implicated in the pathophysiology of tooth resorption in cats.^57,58

While another study could not demonstrate higher 25OHD serum levels in cats with tooth resorption compared to cats without tooth resorption,⁵⁹ there are numerous studies that demonstrate the effects of excess vitamin D and vitamin D metabolites on the periodontium in experimental animals.⁴⁷ These changes in periodontal tissues resemble histological features of teeth from cats with tooth resorption and include periodontal ligament degeneration, hypercementosis, hyperosteoidosis, narrowing of the periodontal ligament space, dentoalveolar ankylosis, and resorption of dental hard tissues. Loss of biologic width (the distance between the bottom of the gingival sulcus and the alveolar margin) and coronal displacement of transseptal fibers have also been reported in these experimental animals, which may provide explanations for two other phenomena commonly seen in the mouth of cats (i.e., thickening of alveolar bone and extrusion of canine teeth).^47,52

Tooth resorption is rarely seen in cats younger than 2 years of age, and clinically obvious disease may not be noted prior to 4 to 6 years of age. Increased age and gingivitis may be risk factors for tooth resorption.50 There is no obvious predisposition with regard to sex, breed, or neuter status. The most commonly affected teeth include the mandibular third premolars; however, any tooth can be affected. Multiple teeth, in some cases the entire dentition, are likely affected throughout a cat’s life.^46,47

Many affected cats will not show clinical signs. Some cats present with oral discomfort, lethargy, anorexia, dehydration, and weight loss. Halitosis, plaque, and calculus accumulation, gingivitis, and gingival enlargement in areas of crown defects may be noted. Nasal discharge and sneezing are occasionally observed when there is severe resorption of maxillary teeth. Repetitive lower jaw motions may be seen during eating, drinking, grooming, or upon palpation of oral and dental tissues.⁴⁶ Alveolar bone expansion (Fig. 24.29) and abnormal tooth extrusion can frequently be observed in the region of canine teeth of cats with tooth resorption (Fig. 24.30).^47,51

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