Distribution and volumetric assessment of initial approximal caries lesions in human premolars and permanent molars using computer-aided three-dimensional reconstruction

Serial sections from 21 extracted premolars and permanent molars, divided i nto three age groups (group 1, 10-19 years; group 2, 20-39 years; group 3, 50-69 years.), were viewed by polarized light microscopy for reconstruction of the caries lesions. The volumes of the lesional body and the transparen t zone, and the volumes of early dentinal lesions were calculated; and an e namel demineralization index (EDI) and an enamel-dentine demineralization i ndex (EDDI), representing the volumetric ratio of the body of the lesion to the translucent zone, and the body of the lesion to the volume of the earl y dentinal lesion, respectively, were determined. The method showed that th ere are three typical sites of individual initial caries lesions at the app roximal surface: within the contact area, in the subcontact area, and in th e cervical area. Volumetric assessment demonstrated a larger volume of the body of the lesion in older teeth with a smaller volume of the translucent zone relative to the lesional body. From these results it can be concluded that there are usually more than one individual initial caries lesions at t he approximal tooth surface. Calculation of demineralization indices demons trated different features for small lesions with pronounced transparent zon es and for large lesions with small transparent zones. The computer-assiste d three-dimensional reconstruction technique and the volumetric assessment are of value in investigations of the micromorphology and progression of na tural caries lesions in permanent teeth. (C) 2000 Elsevier Science Ltd. All rights reserved.