The Formation of Early Carious Lesions in Dental Enamel

Abstract

In order to avoid development of artefacts in prepns. of dental enamel, a series of early carious lesions were examined by reflected light microscopy. Unaffected enamel was not stained by such dyes as alizarin red S or methyl green, whereas carious lesions in the enamel stained quite readily. It would seem that in the structure of normal enamel the Ca is so bound that it is incapable of reacting with the dyes but the formation of red stain by alizarin red S in carious lesions would indicate that here the Ca was in a more available, or even a free, form. This suggests that at least a partial decalcification of the area is one of the earliest changes in the formation of carious lesions. The lesions appeared conoidal in longitudinal section and rectangular in transverse section, thus possessing a shape similar to that of a wedge. The deepest parts of a lesion bore a relationship to the Hunter-Schreger lines and the striae of Retzius appeared to have a strong influence on the general shape of the lesion. The earliest sign of the carious process appeared to be limited to the substance between the prisms. There was no indication whether the organic material in the enamel had been affected or not.