Histology, Tooth

Excerpt

The tooth can be divided into two main parts: the crown and the root. An indentation (cervical line) encircles the tooth marking a distinction between the crown and the root. The crown is the part that emerges from the maxillary or jaw bone, has a hard and translucent surface (enamel); the root anchors the tooth to the alveolar bone and provides blood and nerve supply through the apical foramen.

The enamel is composed mainly of hydroxyapatite, an inorganic substance highly mineralized and aligned in rods to provide maximum protection to the underlying dentin. Mature enamel is acellular; it is non-vital and not sensitive. Enamel cannot regenerate and cannot be replaced. Dentin is produced by specialized cells called odontoblasts that align the matrix inside closely packed tubules; those structures will undergo mineralization, giving structural resistance. The periphery of the dentin is composed of odontoblasts arranged in a picket fence fashion from the underlying pulp and have cellular processes extending into the dentin's tubules. This structure gives sensitivity to the dentin that produces pain when the protective layer of enamel is eroded. In response to physiologic or pathologic stimuli, odontoblasts can upregulate their protein synthetic activity.Pulp is the inner part of the teeth and is composed of loose connective tissue produced by fibroblasts, many small vessels, and nerves. The teeth are anchored to the alveolar bone by the periodontal ligament, composed of fibrous tissue.