QUANTITATION OF ENAMEL DEMINERALIZATION MECHANISMS

将为这些影响建立一个全面的物理模型 外来离子取代和激光照射 羟基磷灰石溶解动力学 待研究的外来离子 是碳酸盐氟化物锶和镁 主要 要检验的假设是，当这些离子被掺入时， 进入磷灰石晶格，晶体的自由能（和 因此，其溶解度）被改变，即使 溶解速率控制相可以不改变。 进行的研究 与碳酸盐磷灰石样品表明， 碳酸盐含量与该晶体之间的自由能关系 自由能源 个别离子的具体假设如下。 碳酸 建议改变溶解度，但不参与速率 控制表面相;氟化物，另一方面，被认为 准备好参与。 锶和镁的作用机制 镁的作用可能是浓度依赖性的。 激光照射明显降低了羟基磷灰石的溶解度， 通过退火除去更易溶解的结晶溶解位点。 外来离子取代对这种效应的相互作用将是 表征了 在本项目期间进行的研究将共同 为外来离子提供了一个基础广泛的机制解释 激光效果。 这些机制将直接 与晶体结构和能量学相关，因此这些 这些研究将是朝着最终 外来离子和激光的原子级定量理解 方面的影响.

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.