Studies on the calcification mechanism of enamel using ion-selective membrane and glass fiber

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Cation-delective membrtance were used as a model cell for tissue cell to get better understanding of calcification mechanism in tooth enamel. Our previous in vitro finding has suggested that hydroxyapatite obtained by hydrolysis of octacalcium phoshate that nucleated on and grew perpendicular to the cation-selective membrane id comparable to human enamel in respect to crystal shape,crystallinity and the degree od orientation.In this report,the influenece of pH and initial concentrations of calcium,phosphate, carbonate,magnesium and fluoride ions on the morphology and orientation of octacalcium phosphate is stafued in the cation-selective membrane system and glass-fiber system to elecidate the calcification mecanism and growrh process in enamel. In order to clarify the reaction that might ge taking place in the diffusion layer on the cation-selective membrane, some reactions were carried out in non-membrane sytem in which precipitation was initiated by adding calcium solution fropwise t … More o phosphate solution. In the membrane system, initial precipitated on the membrane appeared granular in shape and the incresed in size to from a co-agulated granular form, resulting in a creat-like appeatanece. With time, however, they grew outbawd prefetentially perpenficular to the membrance, of which X-tby diffraction pattern was characteristic of oriented OCP.In the non-membrance system, the first precipitation took place when the solution saturtation was slightly undersaturated with respect to reported value of ACP solubility product. Interesting point was that when continued the Ca addition the degree of solution saturation moved alog almost parallel to the solubility line of OCP the chemical potential plot. But, once the Ca addition ceased OCP convert to hydroxyapatite. From these in vitro findings it may behypothsized that in enemel formation feeding rate of Ca^<2+> to mineralixaing fornt is modetrately greater enough to stabilize fibbon-kike COP and enemel prisms might be formwd. %on the contray, in the calcification of bone and dentine the Ca^<24> feeding rate may bre consiferably smaller. Less