QUANTITATION OF ENAMEL DEMINERALIZATION MECHANISMS

将为这些效应开发一个全面的物理模型。 外源离子替代和激光照射对 羟基磷灰石的溶解动力学。待研究的外来离子 碳酸盐、氟化物、锶和镁。少校 需要检验的假设是，当这些离子结合在一起时 进入磷灰石晶格，晶体的自由能(和 因此它的溶解度)被改变，即使 溶出速率控制相不会发生变化。已完成的研究 与碳酸盐磷灰石样本表明，可能有一个线性 碳酸盐含量与该晶体的自由能关系 自由能。 关于单个离子的具体假设如下。碳酸盐 建议改变溶解度，但不参与速率 控制表面相；另一方面，氟化物被认为 随时准备参与。锶和铅的作用机制(S) 镁的作用可能是浓度依赖的。 激光照射明显降低了羟基磷灰石的溶解度 通过退火消除更易溶的结晶溶解位置。 外来离子取代对这一效应的相互作用将是 特色化的。 在这个项目期间要进行的研究将集体进行 为外来离子提供了一个广泛的机理解释 和激光效果。这些拟议的机制将直接 与晶体结构和能量学有关，因此 研究将是朝着最终的 对外来离子和激光的原子能级定量理解 效果。

A comprehensive physical model will be developed for the effects of foreign ion substitution and laser irradiation on the dissolution kinetics of hydroxyapatite. Foreign ions to be studied are carbonate, fluoride, strontium and magnesium. The major hypothesis to be tested is that when these ions are incorporated into the apatite lattice, the free energy of the crystal (and consequently its solubility) is altered, even though the dissolution rate controlling phase may not change. Studies done with carbonate apatite samples suggest that there may be a linear free energy relationship between carbonate content and this crystal free energy. Specific hypotheses for individual ions are as follows. Carbonate is proposed to alter solubility but not participate in the rate controlling surface phase; fluoride, on the other hand, is thought to readily participate. The mechanism(s) by which strontium and magnesium act may be concentration dependent. Laser irradiation reduces solubility of hydroxyapatite, apparently by annealing away the more soluble crystalline dissolution sites. The interaction of foreign ion substitution on this effect will be characterized. The studies to be done during this project will collectively provide a broadly based mechanistic interpretation for foreign ion and laser effects. These proposed mechanisms will be directly relatable to crystal structure and energetics and therefore these studies will constitute a significant step toward an eventual quantitative atomic level understanding of foreign ion and laser effects.