Teeth and Dentition

An adult human has 32 teeth housed in the buccal cavity. Human dentition — the study of teeth with respect to their number, arrangement and development — is described by three terms:

• Thecodont: each tooth sits fixed in its own separate socket in the jaw bone, held by a gomphosis-type joint (a fibrous joint that anchors a peg into a socket).
• Diphyodont: over a lifetime, a human develops only two successive sets of teeth — the temporary milk (deciduous) teeth of childhood, later replaced by permanent teeth.
• Heterodont: humans possess four structurally different types of teeth suited to different jobs — incisors (I) for cutting, canines (C) for tearing, premolars (PM) for crushing and molars (M) for grinding.

Each half of each jaw carries 2 incisors, 1 canine, 2 premolars and 3 molars, giving the dental formula I 2/2, C 1/1, PM 2/2, M 3/3 — that is, 8 teeth x 2 (upper and lower half of one side) = 16 teeth per jaw, and 32 teeth in all. …