tooth

a hard structure used for biting and chewing. Each tooth consists of a root embedded in a socket within the jawbone to which it is attached by the fibrous periodontal membrane. The projecting part of the tooth, called the crown, is covered with a hard resistant layer of enamel (composed primarily of calcium phosphate and calcium carbonate). The root is covered with a thin hard layer of CEMENTUM . Most of the interior of the tooth consists of DENTINE , a hard ivory-like substance that surrounds the inner core or pulp. The pulp contains blood vessels and nerve fibres and is connected with the dentine by means of fine cellular processes. There are four different types of teeth: canine, INCISOR , premolar and MOLAR .