Differential termination times of enamel formation on human deciduous anterior-tooth surfaces revealed by tetracycline labelling.

The positional relationships between the cervical-enamel margin and the intersecting point of a fluorescent (tetracycline) line in dentine, with the outer dentine surface or the dentine-enamel junction, were investigated by ultraviolet microscopy of the human deciduous anterior teeth. The results suggest that enamel formation (1) ended earlier on the mesial than on the distal surface in 18 instances and, nearly simultaneously on both of these surfaces in four, (2) ended earlier on the distal than on the labial surface in all 28 specimens and (3) ended earlier on the labial than on the lingual surface in 14 instances and nearly simultaneously on both of these surfaces in eight instances.

Differential rate of dentin formation on human deciduous anterior tooth surfaces deduced from tetracycline labeling.

Distances between the intersecting points of two fluorescent lines with the outer dentin surface were measured on enlarged microphotographs of ground sections of human deciduous anterior teeth. The results suggested that: extension of odontoblast differentiation is greater on the lingual than on the labial side during the 8 months following birth in incisors, and during the first year in canines; it is greater on the distal than on the mesial side during the 3 months following birth in incisors, and during the first year in canines; in the incisors, dentin formation of newly differentiated odontoblasts is more active on the distal than on the mesial side during the 8 months following birth.