Death in the life of a tooth.

Programmed cell death (apoptosis) constitutes an important mechanism in embryonic development. Although there is substantial evidence for essential roles of apoptosis in organ shaping and controlling of cell number, the mechanisms of these processes are poorly understood. The regulation of cell proliferation to form tooth buds of the appropriate size and at the correct positions must involve a balance between cell division and cell death. Apoptosis has been suggested to play both passive and active roles in bud formation and morphogenesis and in reduction of the dental lamina, as well as silencing of the enamel knot signaling centers. The location of apoptotic cells during tooth development has been described and suggests their temporospatial roles. Unfortunately, there is little functional evidence on these roles, and the aim of this review is to highlight areas where apoptosis may play key roles in odontogenesis.