Relationship between mineral distributions in dentine lesions and subsequent remineralization in vitro

Though the mineral distribution of the dentine carious lesion varies largel y from tooth to tooth and from patient to patient, there are two main distr ibution profiles that characterize natural carious lesions in dentine. Thes e profiles include softened and subsurface lesion types. The mineral distri bution relationship between the starting profile and the profile after remi neralization is not known. In order to study the relational aspects, we hav e produced demineralized dentine samples in vitro with mineral profiles sim ilar to those of typical natural carious lesions, and subsequently reminera lized the samples in a remineralizing solution with various fluoride concen trations (0, 2 and 10 ppm F). The mineral distributions were obtained by us ing an improved microradiographic technique. In addition, the nature of dep osited mineral was analyzed by diamond-coupled total internal reflectance s pectroscopy. Definite relation ship was observed between the original lesio n mineral distribution and the mineral distributions following remineraliza tion. The amount of mineral present in approximately the first 50 mu m of t he lesion influenced the overall mineral profile after remineralization, po ssibly through influencing ion transport. If the amount was high (> approxi mately 10 vol%), the deposited mineral was confined to the surface (0-50 mu m). The original mineral at those depths acted like a nucleus of mineral r egrowth when the amount of residual mineral was intermediate, and like a tr ansport barrier when the surface layer was well mineralized. If a surface b arrier was not present, mineral was deposited at deeper depths in the lesio n. Fluoride effect on dentine remineralization was dependent on the origina l mineral content and its distribution in the lesion. Although a high conce ntration of fluoride was very effective in low-mineral lesions, it produced hyperremineralization on well-mineralized subsurface lesions so that it pr evented effective remineralization especially in deeper lesions. Copyright (C) 2000 S. Karger AG. Basel.