Identification of hypocalcified and demineralized areas in sections of human enamel.

Abstract

HITHERTO, poorly calcified areas in the enamel of ground sections of teeth have been detected either by their permeability to stains, insolubility in dilute acid or by their low absorption of soft X-rays (so-called Grenz-rays). Gottlieb, Diamond and Applebaum1 came to the conclusion that “it is impossible by means of microscopic ground section study, to differentiate between enamel in the matrix stage and fully calcined enamel”. During the preparation of ground sections of teeth with obviously poorly calcified areas of enamel, we were struck by the appearance of these areas when sections were examined in water by transmitted and reflected light. By transmitted light they appear opaque, while the normal enamel is translucent or transparent; by reflected light they appear white. When cleared and mounted in the routine histological manner, they become translucent, and it is often difficult to distinguish them from normal transparent or translucent enamel, but they can be distinguished from pig-mented enamel by the lack of brown pigmentation. Using these criteria, we were able to show, in proved cases of immature acid-insoluble enamel, almost complete agreement between the dark areas in the water-mounted sections and those observed on an X-ray negative after exposure to soft X-rays (Figs. 1 and 2). The soft X-rays used were produced by a commercial type ‘Raymax’ tube with a tungsten target and operated at 20 kV. peak and about 3 m.amp. emission current.