Correlated Electron Probe Microanalysis and Microradiography of Carious and Normal Dental Cementum

Abstract

In order to compare the distribution of elements in carious cementum and root dentin with the morphology of the lesion, a correlated electron probe microranalysis and microradiographic study was carried out. Ground sections of human teeth showing early stages of root surface caries were microradiographed and subsequently analyzed for the presence of Ca, P, F, S, Mg, Na, Fe, Cu, Zn, Sn and Ag. Caries in cementum start as a partial decalcification which soon reaches the peripheral dentin and may extend to a depth of 0.33 mm without any loss of surface contour at the light microscopic level of observation. The pattern of dissolution and reprecipitation of mineral components seems to follow the pattern seen in dentin caries. Although reprecipitation of minerals forming a hypercalcified layer at the surface of the lesion occurs regularly, a surface layer of increased radiopacity may be found even in the absence of this process due to the adsorption of foreign, heavy elements in the surface layer of carious cementum. The relatively high F content normally found in the outer layer and the additional accumulation of F in this layer both from saliva and incident to the outward diffusion of dissolved mineral, result in the development of a particularly distinct zone of recalcification at the surface during the early stages of cementum caries.