The normal adult dentition consists of 32 permanent teeth. The adult dentition has four types of teeth: 8 incisors, 4 canines, 8 premolars, and 12 molars. The primary or deciduous dentition consists of 20 teeth of three types: 8 incisors, 4 canines, and 8 molars. Figure 245-1 shows the eruptive pattern of both the primary and permanent dentition. Figure 245-2 illustrates the most commonly used tooth numbering system; however, description of the tooth type and location is also appropriate.
Normal eruptive patterns of the primary and permanent dentition. mo. = month; yr. = years.
A tooth consists largely of dentin, which surrounds the pulp, the tooth's neurovascular supply (Figure 245-3). Dentin is a homogeneous material produced by pulpal odontoblasts throughout life. Dentin is deposited as a system of microtubules filled with odontoblastic processes and extracellular fluid. The crown, or the visible portion of tooth, consists of a thick enamel layer overlying the dentin. Enamel, the hardest substance in the human body, consists largely of hydroxyapatite and is produced by ameloblasts before eruption of the tooth into the mouth. The root portion of the tooth extends into the alveolar bone and is covered with a thin layer of cementum.
The dental anatomic unit and attachment apparatus.
The periodontium, or attachment apparatus, is essential for maintaining the integrity of the dentoalveolar unit. The attachment apparatus consists of a gingival component and a periodontal component. The gingival component includes the junctional epithelium, gingival tissue, and gingival fibers and primarily functions to maintain the integrity of the periodontal component. The periodontal component includes the periodontal ligament, alveolar bone, and cementum of the root of the tooth and forms the majority of the attachment apparatus. Disease states such as gingivitis and periodontal disease weaken and destroy the attachment apparatus, resulting in tooth mobility and tooth loss.1
Gingival tissue is keratinized stratified squamous epithelium. It can be divided into the free gingival margin and the attached gingiva. The free gingiva is the portion that forms the 2- to 3-mm-deep gingival sulcus in the disease-free state. The attached gingiva adheres firmly to the underlying alveolar bone. The nonkeratinized alveolar mucosa extends from the attached gingiva to the vestibule and floor of the mouth. The mucosal tissue of the cheeks, lips, and floor of the mouth is also comprised of nonkeratinized squamous epithelium.
Table 245-1 lists common causes of orofacial pain. ...