Homeostatic maintenance of mineralization in dental hard tissue by saliva

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This research was to clarify crystallographically the role of saliva or a remineralizing solution in demineralized dentin and to determine the effectiveness of a food additive to promote acid resistance in root dentin exposed during periodontal-disease therapy.We used completely impacted human third molars extracted for therapeutic reasons from patients aged from 20 to 40 yr. Informed consent was obtained for the experimental use of the extracted teeth. The Ethics Committee of Tokyo Dental College approved both the acquisition and the experimental use of the materials.1. Remineralization of demineralized dentinRemineralization by means of saliva would seem to be excellent because a remineralized layer forms on the surface and remineralization throughout improves. But HR-TEM shows that dense crystal deposition at the surface layer may actually inhibit mineral permeation to lower levels. The addition of F-Ca-CO to saliva, however, causes mineralization, not at the surface, but in deeper … More layers and therefore is thought to promote overall mineralization in the long term. The degree of deep-layer mineralization induced by a remineralizing solution is thought to be slight because the solution is low in Ca and P. It was believed that the addition of F-Ca-CO would cause high-degree remineralization by increasing Ca and adding F. The addition of F alone caused strong remineralization at the surface layer, whereas the addition of F-Ca-CO caused remineralization from the inner regions of the demineralized layer. This phenomenon led to the idea that something other than F plays a big role.2. Tests on Dentinal Demineralization ResistanceImmersion in a remineralizing solution increased dentinal resistance to demineralization, and the addition of F-Ca-CO increased it still further. Because it causes greater mineral deposition owing to the actions of Ca and F, the additive improves crystal formation. Consequently, the addition of F-Ca-CO is believed to strengthen resistance to demineralization. Less