Abstract: | 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. |