The Influence of the Enamel Organ Upon the Calcification of Dentin and the Functions of the Odontoblasts

Abstract

Enamel hypoplasia was produced in rats by a rachitogenic diet, followed by 3-6 days of healing, and then returned to the rachitogenic ration. Animals were sacrificed from 3-42 days later, and the incisor teeth examined histologically. The influence of the enamel organ not only controls differentiation of the odontoblast, but is operative on their subsequent functions and maintenance as follows: In the absence of enamel matrix formation in rats'' incisor teeth, calcification of the corresponding dentin does not occur. The odontoblasts corresponding to the uncalcified dentin lose their characteristic appearance about 18 days after calcification should have occurred and lay down less dentin matrix in which they have become embedded. A stimulus to cause dentin calcification is apparently received by the odontoblasts from the enamel organ at the time enamel matrix is first formed. The effects of this stimulus persist throughout the life of the cell. In the absence of the stimulus, the odontoblasts can continue to lay down matrix for about 18 more days, after which they regress.