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

为了更好地了解牙釉质钙化机制，我们将阳离子缺失膜作为组织细胞的模型细胞。我们之前的体外研究表明，通过磷酸八钙水解得到的羟基磷灰石在阳离子选择膜上成核并垂直生长，在晶体形状、结晶度和取向度方面与人类牙釉质相当。本报告通过钙、磷酸盐、碳酸盐、镁和氟离子的pH和初始浓度对磷酸八钙形态和取向的影响，在阳离子选择性膜系统和玻璃纤维系统中进行刻画，以阐明牙釉质中的钙化机制和生长过程。为了阐明在阳离子选择膜的扩散层中可能发生的反应，在非膜系统中进行了一些反应，在非膜系统中，通过将钙溶液顺向加入到磷酸溶液中引发沉淀。在膜系统中，最初沉淀在膜上呈颗粒状，逐渐增大为共凝颗粒状，形成巨形外观。然而，随着时间的推移，它们逐渐向外倾斜，倾向于垂直于膜，其x - x衍射图具有定向OCP的特征。在非膜体系中，当溶液饱和度相对于报告的ACP溶解度积值略不饱和时，第一次沉淀发生。有趣的是，当继续添加Ca时，溶液的饱和度几乎平行于OCP的溶解度线（化学势图）。但是，一旦Ca的加入停止，OCP就会转化为羟基磷灰石。从这些体外实验结果可以推测，在灌肠形成过程中，Ca^<2+>对矿化锋的摄食速率适中，足以稳定纤维样COP，并可能形成灌肠棱镜。相反，在骨和牙本质的钙化中，Ca^<24>的摄食速率可能要小得多。少

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