X-ray microanalytical histochemistry of human circumpulpar and mantle dentine

An X-ray microanalytical histochemistry study was carried out, on thick sections observed under scanning electron microscopy, of five freshly extracted human premolars and five molars. In particular the circumpulpar and mantle dentine were examined to determine levels of calcium, phosphorus and sulphur, the basic elements involved in the process of biomineralization. Semiquantitative analysis was subsequently performed after the appropriate ZAF (Z, atomic number; A, absorption; F, secondary fluorescence) correction. Ca/P mass ratio was found to be similar for both regions in molars and slightly higher in circumpulpar dentine in premolars implying that this parameter is independent of the processes of biomineralization in the two dentinal regions. In contrast, statistically significant differences were recorded in sulphur content upon comparing mantle and circumpulpar dentine between premolars and molars (P less than 0.02). If sulphur, which has been associated with sulphated glycosaminoglycans (GAGs) decreases as mineralization progresses it would therefore seem reasonable to posit sulphur-rich areas in both topographical regions of the matrix--more significant in premolars than molars--able to undergo subsequent mineralization if required. The possible application of these findings in remineralization therapies is suggested.