Studies on the Mechanism of Early Dental Caries

¹ Department of Anatomy, The Hebrew University-Hadassah Medical School and School of Dentistry, Jerusalem, Israel

Experimental data related to some of the phenomena involved in chemically induced lesions have been compared with those of early caries. Two chemical agents were examined—saturated buffer solutions and ethylenediaminetetraacetate (EDTA). Two main routes of diffusion were indicated—the Retzius lines and the interrod substance.

The agreement with acid action as a trigger mechanism applies to some phenomena associated with early caries, while certain characteristics of progressing caries suggest the possibility that chelation may form one of the underlying mechanisms.

Mild acids attack the subsurface, while chelating agents cause a deeper dissolution of the interrod substance, presenting a picture of sharply projecting rod ends. There are no evidence of chalky spot formation by EDTA, no swelling, and no detachment of the enamel from the dentin.

The effect of chelating agents is also characterized by the absence of alternating zones of demineralization, since the minerals are transported away.

One of the fundamental characteristics of early caries is the yellowish pigmented dentinal cone subjacent to the chalky enamel rods. Its origin and nature present a problem awaiting solution. It is not reproducible in model systems in vitro until present. The recognition of the specific focal nature of the pigmented dentinal cone calls for a more concentrated study of this phenomenon.