The Pathways of the Early Carious Process

I. Histologic Study

¹ Department of Biochemistry and Zoller Memorial Clinic, University of Chicago

A study was made of transverse sections taken from early and advanced carious zones and impregnated by the mercury sulfide technique of Nishimura. Impregnated sections from non-carious unerupted third molars were also studied.

The earliest impregnation was seen at the periphery of the rod in the sheath, indicating that this is the first site of change in caries. In more advanced areas the prism body became progressively impregnated from its periphery toward its center, leaving the interprismatic substance unstained.

The sheath was found to impregnate with mercury sulfide in an unerupted third molar but not in sound enamel of posteruptive teeth, indicating that it does not calcify completely until very late in development.

The significance of the sheath in development and in caries is discussed.