Innervation of the Teeth and Periodontium

Abstract

The common pulpal nerve arises as a union of the branches of the various dental nerves which enter the apical periodontal membrane of all the surfaces surrounding the tooth. In the coronal portion of the pulp, the common pulpal nerve breaks up into cuspal nerves which course toward the cuspal horns. The termination of these nerves is mainly in the odontoblastic layer; however, a few nerves enter the predentin where they form a loop to return to the odontoblastic layer. The nerve supply to the periodontal membrane arises from the dental and interalveolar nerves, branches of the alveolar nerve. The dental nerve fibers supply the periapical region and pass gingivally to form a united bundle with perforating branches of the interalveolar nerves. Two types of nerve endings are found in the periodontal membrane: (1) Non-medullated nerve fibers may unite at their terminals to form an arborization; fine, delicate fibrils arise from this network to end as “free nerve endings” among the stroma cells, cementoblasts, and the cementum. (2) Medullated fibers may lose their myelin sheaths and the naked fibrils terminate into an elongated spindle-like structure. Gingival innervation is derived from two sources: (1) fibers arising from the nerves of the periodontal membrane, and (2) fibers originating from the labial, buccal or palatal nerves. As these fibers pass through the connective tissue, terminal twigs are given off which supply the tunica propria. Intrapapillary and intraepithelial nerve endings are scarce in the epithelial attachment and marginal gingiva. On the other hand, the attached gingiva contains both types of nerve endings.