A new two-site model for hydroxyapatite dissolution in acidic media☆
A new two-site model for hydroxyapatite dissolution in acidic media☆
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羟基磷灰石在酸性介质中溶解的新双位点模型☆
DOI：
10.1016/0021-9797(78)90016-4
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发表时间：
1978
影响因子：
9.9
通讯作者：
Maw
中科院分区：
文献类型：
--
作者：
J. Fox;W. Higuchi;M. Fawzi;Maw
提出了一个具有两种不同类型的羟基磷灰石（HAP）晶体溶解位点的物理模型。其中一个位置（1号位置）与HAP晶体沿沿着c轴位错的溶解有关，并且是溶解发生在部分饱和溶液中时的重要位置。只有当溶解发生在几乎完全不饱和的溶液中时，2号位点才是活性的，并且由于其更大的表观速率常数，在这些条件下是更重要的溶解位点。在物理模型块中，牙釉质或压缩的HAP颗粒被表示为这些HAP晶体的多孔基质，其具有被溶解介质渗透的间隙空间。模型在各种情况下的行为可以通过将Fick第二定律扩散方程与溶解位点行为的动力学方程相结合并求解所得的边值问题来计算。该模型是能够占溶解动力学的实验变量（欠饱和度，钙磷比，和有效的扩散层厚度）的变化范围内。该模型还正确地预测了必要的条件为带状相对于表面溶解：高部分饱和度，粘性溶解介质，或存在的网站2号溶解抑制剂。在单晶水平的溶解形态的电子显微镜研究也完全符合该模型。最后，对釉质再矿化的现有数据的检查表明，作为位点1溶解的结果而形成的孔可能是再矿化的主要位点。
A physical model featuring two distinct types of dissolution sites for hydroxyapatite (HAP) crystals is presented. One of these sites (site No. 1) is associated with dissolution along c axis dislocations of HAP crystals and is the important site when dissolution occurs into partially saturated solutions. Site No. 2 is active only when dissolution occurs into nearly completely unsaturated solutions, and, because of its greater apparent rate constant, is the more important dissolution site under these conditions. In the physical model block dental enamel or a compressed HAP pellet is represented as a porous matrix of these HAP crystals with interstitial spaces which are permeated by the dissolution medium. The behavior of the model for various situations can be calculated by combining Fick's second law equation for diffusion with the kinetic equations for the behavior of the dissolution sites and solving the resulting boundary value problem. This model is capable of accounting for dissolution kinetics over a range of variation of experimental variables (degree of undersaturation, Ca P ratio, and effective diffusion layer thickness). The model also correctly predicts the conditions necessary for zonal as opposed to surface dissolution: high partial saturation, a viscous dissolution medium, or the presence of a site No. 2 dissolution inhibitor. Electron microscopic studies of dissolution morphology at the single crystal level are also in full agreement with the model. Finally, an examination of the available data on enamel remineralization suggests that the holes formed as a result of site No. 1 dissolution are likely the primary sites for remineralization.