An histological investigation of invaginated human incisors.

The outlines of the invaginations resembled bottles with narrow necks directed at the incisal edge of the teeth. It is proposed that this form is genetically predetermined and that an active or passive infolding gives rise to the invaginations. In one case investigated out of six, an interruption of the dentin layer, surrounding the invagination, was found. This could become a susceptible site for post-eruptive bacterial invasion. In all cases, considerable amounts of enamel with normal structure were found in the invagination. The centrally positioned connective tissue was richly supplied with blood vessels and lined with layers of epithelial tissue, demonstrating various stages of an involutive enamel organ.