Feline Dentistry. Jan Bellows
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joint (TMJ): The area where the condylar process of the mandible articulates with the mandibular fossa of the temporal bone.
Tooth (T): Hard structure embedded in the jaw; used for biting and chewing.
Tooth numbering: The existence of the conventional anatomical naming of teeth as well as the various tooth numbering systems is recognized. In cats and dogs, the correct anatomical names of teeth are (right or left), (maxillary or mandibular), (first, second, third or fourth), (incisor, canine, premolar, molar), as applicable, written out in full or abbreviated. The modified Triadan system is presently considered to be the tooth numbering system of choice in veterinary dentistry; gaps are left in the numbering sequence where there are missing teeth (for example, the first premolar encountered in the feline left maxilla is numbered 206, not 205; the two lower right premolars are 407 and 408, not 405 and 406). The use of both anatomical naming and the modified Triadan system are acceptable for recording and storing veterinary dental information. The use of anatomical names in publications is required by many leading journals and is recommended. It offers an advantage in that veterinary dental publications are more understood by other health professionals and scientists with an interest in veterinary dentistry.
Ventral margin: Free ventral border.
Vestibular/Buccal/Labial: Vestibular is the correct term referring to the surface of the tooth facing the vestibule or lips; buccal and labial are acceptable alternatives. Labial refers to the facial surface of the incisors and canines. Buccal refers to the facial surface of the premolars and molars.
Zygomatic arch (ZYG): Consisting of the zygomatic process of the temporal bone and the temporal process of the zygomatic bone; also called zygoma.
An understanding and appreciation of feline dental pathology, treatment, and prevention requires detailed knowledge of the structure and function of oral tissues including the teeth, supporting periodontal tissues, bones, tongue, lymph nodes, salivary glands, blood supply, muscles, and nerves.
1.1 Oral Cavity
The oral cavity extends from the lips to the pharynx, bounded laterally by the cheeks, dorsally by the palate, and ventrally by the tongue and intermandibular tissues. The oral cavity is divided into the oral cavity proper and the oral vestibule. Within the oral cavity proper are the hard palate, soft palate, tongue, and the floor of the mouth. The hard palate is formed by the palatine processes of the incisive and maxillary bones and the horizontal laminae of the palatine bones. The mucosa covering the hard palate consists of cornified stratified squamous epithelium, which is developed into seven or eight transverse curved ridges (palatine rugae). The palatine rugae have thick tough connective tissue support, the mucoperiosteum, which is continuous with the periodontal ligaments of the upper teeth. The mucosa of the hard palate ends abruptly laterally at its junction with the short palatal free gingiva. The incisive papilla is located on the midline cranial to the first transverse ridge and just caudal to the upper central incisor teeth. On either side of this papilla are the incisive ducts that extend caudodorsally through the palatine fissures into the floor of the nasal fossae. This duct communicates with the vomeronasal organ. Caudally, the oral cavity proper ends at the palatoglossal folds.
The palatoglossal arch (also called palatoglossal fold) is a fold of mucous membrane which extends from the soft palate to the side of the tongue. The palatoglossal arch marks where the mouth becomes the pharynx. The palatoglossus muscle is one of the four extrinsic muscles of the tongue. The paired muscles create ridges of mucous membrane in the lateral pharyngeal wall called the palatoglossal arches (also known as the anterior pillars of the fauces). The palatoglossus muscle runs in the anterior palatoglossal arch, and the palatopharyngeus muscle runs in the palatopharyngeal arch of the tonsillar fossa. These muscles pull the back of the tongue upward toward the soft palate to seal the oral cavity from the pharynx. The palatine tonsils lie in shallow fossae located approximately 1.5 cm caudal to the palatoglossal folds.
The oral vestibule spans between the lips, cheeks, and dental arches. The labial vestibule is the space between the incisors, canines, and lips. The buccal vestibule is the space between the cheek teeth and the cheeks (Figure 1.1a–c).
1.2 Mucosa
Oral mucosa covers the surface of the mouth with the exception of the gingiva which is a specialized form of mucoperiosteum. The outer layer of mucosa is composed of variably pigmented nonkeratinized and parakeratinized stratified squamous epithelium. The submucosa is composed of loose connective tissue, salivary glands, blood vessels, muscle fibers, lymphatics, and salivary ducts. The submucosa of the palate is composed of dense collagen.
Oral mucosa can be categorized based on function and histology:
1 Masticatory mucosa – keratinized stratified squamous epithelium, found on the dorsum of the tongue, hard palate, and attached gingiva.
2 Lining mucosa – nonkeratinized stratified squamous epithelium, found almost everywhere else in the oral cavity, including:Buccal mucosa – inside lining of the cheeksLabial mucosa – inside lining of the lipAlveolar mucosa – covering the alveoli extending to the buccal/labial mucosa.
3 Specialized mucosa – in the regions of the taste buds on lingual papillae on the dorsal surface of the tongue. It contains nerve endings for general sensory and taste perception as well as filiform keratin projections on the hard palate mucosa.
Figure 1.1 (a) Maxilla. (b) Maxillae, mandibles and sublingual areas. (c) Right maxilla and mandible.
1.3 Muscles
The muscles of mastication that close the jaws are the temporal, masseter, and medial and lateral pterygoid muscles, all of which are innervated by the mandibular nerve (the only motor branch of the trigeminal nerve). The digastricus muscle opens the mouth. Its rostral belly is innervated by the mandibular branch of the trigeminal nerve, while its caudal belly is innervated by the facial nerve. The body (the rostral two‐thirds) of the tongue is attached ventrally to the midline of the floor of the mouth by the lingual frenulum.
1.4 Tongue
The tongue has important functions in grooming, eating, drinking, and vocalization. The tongue is composed of both striated intrinsic and extrinsic muscles. The body of the tongue comprises the rostral two‐thirds, the root comprises the caudal one‐third and is attached to the hyoid apparatus. The genioglossus muscle depresses and is the only muscle to protrude the tongue, the hyoglossus and styloglossus both depress and retract the tongue.
The dorsal surface of the tongue is covered by keratinized stratified squamous epithelium that forms papillae which are responsible for taste, temperature control (through transfer of saliva from the mouth to fur) and grooming. The dorsal aspect of the lingual mucosa is specialized, having five types of papillae. They are filiform, fungiform, foliate, vallate, and conical. Filiform and fungiform papillae occupy the dorsal surface of the tongue body. The vallate papillae separate the tongue body and root dorsally. Vallate, foliate, and conical papillae occupy the tongue root (Figure 1.2).
Figure 1.2 Tongue papillae.
Pillars of