Picture of Teeth
- Enamel is the hard, outermost layer of teeth. The portion of the tooth above the gum line, the crown, is covered by enamel. Enamel is susceptible to decay (cavities) if it is eroded by acids produced by bacteria on the teeth that feed on sugar.
- Cementum is the hard outer layer of teeth under the gum line. The cementum helps anchor the teeth to the gums and the jaw.
- Dentin is the living middle portion of the tooth. Cells in the dentin secrete the hard material that makes up the enamel.
- The pulp and root canals are the inner most portions of teeth that house blood vessels and nerves.
- The periodontal ligaments are tough connective tissues that anchor the teeth into the jawbone.
By the age of 18 to 21, adults have 32 permanent teeth. These include 8 incisors, 4 canines, 8 premolars, 8 molars, and 4 wisdom teeth. Many young adults have their wisdom teeth removed to prevent crowding of the teeth.
Text References: "Tooth." American Dental Association. "Eruption Charts." American Dental Association.