Knowledge of the specific distribution of the nerves supplying the dental arches and oral cavity is important for understanding the basis of orofacial pain, assessing nerve damage of the oral tissues, and determining the appropriate nerve to anesthetize for different dental procedures. The following chapter describes the anatomical and structural components of the teeth along with the innervation to the pulp and periodontium. The trigeminal pathway for pain, temperature, mechanosensory, and proprioceptive input is briefly reviewed. A detailed description of central trigeminal pathways is covered in Chapter 13.
A total of 20 deciduous teeth develop prenatally within the bony sockets (alveoli) of the mandibular and maxillary dental arches. The eruption of the primary teeth begins postnatally in the sixth month and is complete by 3 years of age.
The complete primary dentition consists of 10 teeth in each dental arch, with each side of the arch (quadrant) containing 3 basic tooth forms: 2 incisiform (incisors), 1 caniniform (canines), and 2 molariform (molars). The incisors, canines, and molars function in biting, tearing, and grinding, respectively.
The complete permanent dentition contains 32 teeth in total, with 16 in each jaw. The teeth are sequentially numbered, 1 to 32, in a clockwise direction, beginning with the upper right third maxillary molar as tooth 1 and continuing to the lower right third mandibular as tooth 32 ().
Each half of the maxillary and mandibular dental arch contains two premolar (bicuspids) teeth that function in piercing foods. The premolars are unique to the permanent dentition and replace the two deciduous molars.
Fig. 25.1 Deciduous and permanent teeth of a 6-year-old child. The anterior bone was removed above the roots of deciduous teeth. Frontal view of the (a) maxillary and (b) mandibular arch illustrating the erupted deciduous teeth and the position of the developing crowns of the anterior permanent teeth and permanent premolars. The permanent incisors and canines are positioned palatal and lingual to the primary teeth. Note the crowns of the two permanent premolars in both arches are visible in the mandibular arch between the roots of the primary molars. By 6 years of age, all deciduous teeth have erupted and are present, along with the first permanent tooth, the first permanent molar. Note the erupted permanent mandibular molar (6-year molar) with a portion of the root developed is visible. Root formation continues after tooth eruption and growth of the jaw. (Reproduced with permission from Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy Second Edition, Vol 3. ©Thieme 2016. Illustrations by Markus Voll and Karl Wesker.)
Fig. 25.2 Universal numbering system of adult teeth; numbering shown from the perspective of the viewer. The universal numbering system is commonly used in the United States to designate the position of the permanent teeth within the dental arch. Teeth in both arches are numbered sequentially, 1 to 32, in a clockwise direction, beginning with the upper right maxillary third molar as number 1 and continuing to the left maxillary molar (tooth 16). The numbering of the lower arch continues clockwise from 17 to 32. (Reproduced with permission from Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy Second Edition, Vol 3. ©Thieme 2016. Illustrations by Markus Voll and Karl Wesker.)
Fig. 25.3 Arrangement of permanent teeth within the maxillary (upper) and mandibular (lower) dental arches. (a) Inferior view of the maxilla. (b) Superior view of the mandible. Chewing surfaces are shown on the left side. Each arch contains 16 teeth arranged bilateral and symmetrical within two quadrants. Each quadrant contains 2 incisors, 1 canine, 2 premolars, and 3 molars. The alveolar process after removal of teeth can be seen on the left side. Support for the tooth is provided by the periodontal ligament and the components of the alveolar process, which include an outer cortical plate, intervening spongy bone, and the alveolar bone proper, which lines the dental alveoli (tooth sockets). The interalveolar septum lies between the adjacent alveoli, and an inter-radicular septum is present in the alveoli anchoring multirooted teeth. (Reproduced with permission from Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy Second Edition, Vol 3. ©Thieme 2016. Illustrations by Markus Voll and Karl Wesker.)
Fig. 25.4 Designation of tooth surfaces and directions of the dental arches. (a) Inferior view of the maxillary dental arch. (b) Superior view of the mandibular dental arch. Buccal, distal, and occlusal views of the right mandibular first molar (tooth 30). The coronal, apical, and cervical directions of a tooth and the approximal surfaces, which contact, or face, the adjacent teeth are also depicted. These designations are used to describe the precise location of small carious lesions. (a: Reproduced with permission from Baker EW. Anatomy for Dental Medicine. Second Edition. © Thieme 2015. Illustrations by Markus Voll and Karl Wesker. b: Reproduced with permission from Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy Second Edition, Vol 3. ©Thieme 2016. Illustrations by Markus Voll and Karl Wesker.)
The crown is the portion of the tooth visible in the oral cavity and may be subdivided into three regions: an incisal one-third (anterior teeth) or occlusal one-third (posterior teeth), a middle one-third, and a cervical one-third.
The cervix (neck) of the tooth refers to the junction between the crown and the root of the tooth. The body of the tooth contains dentin, a mineralized tissue layer composed of numerous fluid-filled dentinal tubules. Dentin provides structural support to the overlying enamel and cementum and surrounds the pulp cavity.
The mineralized regions of the crown and the root surround and protect an inner core of richly innervated and well-vascularized loose connective tissue (CT), known as the dental pulp. The pulp tissue extends from the crown to the root and resides within an anatomical space known as the pulp chamber and root canal, respectively.
Fig. 25.5 Structures and anatomical regions of the tooth. The longitudinal section of the mandibular incisor. Enamel covers the crown of the tooth from the cusp to the cervix (neck). The cementum covers the external surface of the root and anchors the tooth to the alveolus via the periodontal ligament. The dentin, which supports the overlying enamel and cementum, and surrounds the pulp cavity, forms the body of the tooth. The apical foramen is the opening at the tooth apex that permits the passage of the neurovascular structures from the periodontal tissue to the pulp cavity. (Reproduced with permission from Schuenke M, Schulte E, Schumacher U. THIEME Atlas of Anatomy Second Edition, Vol 3. ©Thieme 2016. Illustrations by Markus Voll and Karl Wesker.)
The periodontium refers to the tissue that supports the teeth in the upper and lower dental arches. The structures of the periodontium include cementum, periodontal ligament (PDL), alveolar bone, and gingiva ().