The control of ingress of albumin into developing enamel from adjacent dentine of the rat incisor.

The present study used an immunohistochemical approach to map the distribution of albumin within the dentine adjacent to the developing enamel of both impeded and unimpeded rat incisors to determine if the dentine could be a possible route of entry for this protein into the developing enamel matrix. In dentine adjacent to the secretory and transition stages of the developing enamel, the dentinal tubules were labelled only over approximately the pulpal quarter of their length. The bulk of the dentine showed no labelling. However, labelling within the dentine appeared at the ADJ at a position approximately 2.5 mm occlusal to the distal root of the first molar, adjacent to enamel with no visible residual matrix. The results of this study suggest that adventitious ingress of albumin into enamel from the dentine is restricted during enamel secretion and can only potentially occur once enamel maturation has been initiated.