MECHANISMS--NORMAL & PATHOLOGICAL ENAMEL MINERALIZATION

釉质形成的过程包括几个明确的阶段 最终形成高度矿化的成熟釉质。 干扰（例如， 摄入高于最佳剂量的氟化物） 导致有缺陷的釉质结构， 不希望的，对物理磨损的抵抗力较低，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 从而形成釉质微晶。 特别重要的是 测定液体中的钙、磷酸盐和pH值 釉质形成的初始阶段。 特殊微量分析 技术将用于这一目的，与牛和 猪牙釉质 将检查与釉质相关的蛋白质 从理论上讲。 2)釉晶体表面的Ca和P池来自分泌型， 过渡期和成熟期将由同位素交换决定 与45Ca和33P，以获得有关性质的信息（和可能的 转化）的生长矿物。 釉质表面将通过吸附实验，使用小 合成肽作为吸附物，也通过晶体生长 实验使用脱蛋白的牙釉质作为溶液中的种子 相对于羟基磷灰石钙过饱和。 3)釉原蛋白和釉蛋白与磷灰石表面的相互作用将 使用模型系统进行研究，即，测定其吸附性 羟基磷灰石上的等温线。 4)磷灰石晶体的选择性渗透取向 膜。 这种实验是一种近似于 一种假设的机制， （垂直于Tomes过程）由电化学过程确定。 膜的性质和一种限制离子的流动方向， 也就是说，钙 建议首先用牛和牛来研究上述方面， 猪的牙釉质，然后用大鼠。 通过大鼠模型， 将涵盖各种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.