Optical and microradiographic appearance of intact and worn human coronal dentine

Abstract

Ground sections of the coronal dentine of unerupted teeth, intact erupted teeth, and teeth with dentine exposed by attrition were studied. Optically, an opaque zone centrally in the incisal dentine, extending from the dentine-enamel junction to the pulp horn, was observed in all teeth. The optical appearance of the opaque zone was considered to be due to developmental structural irregularities of the dentine at this location, causing an increased diffuse reflection and scattering of the light. Microradiographically, a hypermineralized streak bordered by hypomineralized bands, extending from the incisal tip of the dentine to the pulp horn, was observed. In young teeth, peritubular dentine was usually absent in these areas, and the variations in the degree of mineralization was due to the intertubular dentine. The hypermineralized central streak was often interrupted by a slit or a chain of holes, probably due to crowding of odontoblasts during dentine formation. Exposure of the dentine by attrition led to an increase in the mineral content of the tissue. The exposed dentine, however, was not evenly mineralized. The mantle dentine and bands at the borders of the opaque zone were hypomineralized as compared to the adjacent dentine. The highest mineral content was found in the central area of the exposed dentine, and especially in the central streak.