MECHANISMS FOR NORMAL AND PATHOLOGICAL ENAMEL MINERALIZA

釉质形成过程包括几个明确的阶段。 最终形成高度矿化的成熟牙釉质。干扰(例如， 摄入高于最佳剂量的氟化物)在上述任何阶段 导致有缺陷的釉质结构，这可能是美学上的 不受欢迎的，不太耐穿的，或更容易受到 龋齿形成。本提案试图获得关于 以下几点： 1)介质的物理化学性质的表征 形成了哪些釉质微晶。特别重要的是 水中钙、磷和pH值的测定 牙釉质形成的初始(乳酪状)阶段。特种微量分析 技术将用于该目的，与牛和 猪牙釉质。与牙釉质相关的蛋白质将被检查 电泳法。 2)来自分泌物的釉质晶体的表面钙磷池， 过渡期和成熟期将通过同位素交换来确定 用45Ca和33P获取有关自然(和可能的)信息 转变)正在生长的矿物。进一步刻画了 釉质表面将通过吸附实验进行小量使用 合成肽作为吸附物，也可以通过晶体生长 脱蛋白牙釉质作为溶液种子的实验 相对于羟基磷灰石来说是过饱和的。 3)釉原蛋白和釉质蛋白与磷灰石表面的相互作用 使用模型系统进行研究，即确定它们的吸附 羟基磷灰石上的等温线。 4)渗透性选择对磷灰石晶体可能取向的影响 膜。这种实验是一种近似于 釉质微晶取向的假设机制 (垂直于Tomes过程)由电化学法确定 膜的性质和一个限制离子的流动方向， 也就是说，钙。 建议先用牛和黄牛研究上述方面 猪牙釉质，然后是老鼠牙釉质。在大鼠模型中，调查 将覆盖不同氟化物制度下的动物。

The process of amelogenesis comprises several well-defined stages culminating in highly mineralized mature enamel. Disturbances (e.g., ingestion of fluoride at higher than optimum doses) at any of those stages result in a defective enamel structure which may be aesthetically undesirable, less resistant to physical wearing, or more susceptible to caries formation. The present proposal attempts to gain information on the following points: 1) Characterization of the physical chemical properties of the medium in which enamel crystallites are formed. Of particular importance is the determination of the calcium, phosphate and pH values of the fluid in the initial (cheese-like) stage of enamel formation. Special microanalytical techniques will be used for that purpose in conjunction with bovine and porcine enamel. The proteins associated with the enamel will be examined electrophoretically. 2) The surface pools of Ca and P of the enamel crystals from the secretory, transitional and maturing stages will be determined by isotopic exchange with 45Ca and 33P to obtain information on the nature (and possible transformations) of the growing mineral. Further characterization of the enamel surface will be done through adsorption experiments using small synthetic peptides as adsorbates and, also, through crystal growth experiments using the deproteinated enamel as seeds in solutions supersaturated with respect to calcium hydroxyapatite. 3) The interaction of amelogenins and enamelins with apatitic surfaces will be investigated using model systems, i.e., determining their adsorption isotherms onto hydroxyapatite. 4) The possible orientation of apatitic crystals by permselective membranes. This kind of experimentation is a first approximation to a postulated mechanism in which the orientation of the enamel crystallites (perpendicular to the Tomes processes) is determined by the electrochemical properties of the membrane and the direction of flow of one limiting ion, i.e., calcium. It is proposed to study the aspects described above first with bovine and porcine enamel and then with rats. With the rat model, the investigation will cover animal under various fluoride regimes.