Introduction
Teeth are the main part of the supporting section of the masticatory system. Each one is a living organ built from three hard tissues around a soft pulp, and held in its socket by the periodontium.
Types of dentition
Animals differ in what their teeth look like and in how often they are replaced.
So human teeth are heterodont and diphyodont: 20 primary teeth erupt between about 6 months and 2 years, and from age 6 they are replaced one by one by the 32 permanent teeth, mostly by age 12–13.
Parts of a tooth
- Crown (corona dentis): covered with enamel.
- Root (radix dentis): covered with cementum and held in the alveolus. A tooth may have one, two, three or more roots; where they split is the furcation (bifurcation or trifurcation).
- Neck (cervix, collum dentis): the narrow zone where crown meets root, at the cement-enamel junction (CEJ).
- Pulp cavity: a coronal pulp chamber and one or more root canals, open to the body only at the apical foramen.