On the incremental lines in human dentine as revealed by tetracycline labeling.

Growth of human dentine was investigated in extracted permanent teeth exhibiting more than two tetracycline lines. It was concluded that: (1) The secretory activity of an odontoblast varies considerably during its life cycle, and likewise the rate of migration of the odontoblast cell body varies. Odontoblast secretion and migration as a general rule start slowly, reach a peak and then slow up as dentine production nears completion. (3) The activity of a particular odontoblast varies with the type of tooth with which it is associated and with its position within the tooth, as well as with the particular stage reached in its life cycle.