Solubility of human enamel mineral.
Solubility of human enamel mineral.
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发表时间：
1990-09
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通讯作者：
E. Moreno;T. Aoba
中科院分区：
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作者：
E. Moreno;T. Aoba
在 25 摄氏度的受控 CO2 分压（与 N2 的混合物中为 0.005% 至 3.33%）下，研究了人牙釉质在稀磷酸溶液（0.07 mMols/L 至 1.54 mMols/L）中的溶解度。牙釉质矿物被认为是含有具有化学计量的酸式磷酸盐的碳酸磷灰石。 [Ca]5-x-y[HPO4]v[PO4]3-x[CO3]w[OH]1-x-y。在平衡期间，如在电子显微镜下观察到的，第二磷灰石相沉淀。溶解度模型的改进与适应的化学计量和第二相的沉淀一致。即使在最低的 CO2 分压下沉淀，后者似乎也具有与釉质矿物相似的碳酸盐含量，这表明约 0.3 摩尔含量的碳酸盐可以稳定磷灰石晶格。根据搪瓷矿物采用的化学计量Ca4.34 (HPO4).08 (CO3).29 (PO4)2.63 (OH).05，计算其溶度积常数为Ksp = 1.74 (+/- 0.081)x10(-6)，表示为平均活度积。
The solubility of human enamel was investigated in dilute phosphoric acid solutions (0.07 mMols/L to 1.54 mMols/L) under controlled partial pressures of CO2 (0.005% to 3.33% in mixtures with N2) at 25 degrees C. The enamel mineral was considered as carbonatoapatite containing acid phosphate having the stoichiometry [Ca]5-x-y[HPO4]v[PO4]3-x[CO3]w[OH]l-x-y. During equilibration, a second apatitic phase precipitated, as observed under the electronmicroscope. Solubility models are advanced consistent with the adapted stoichiometry and the precipitation of the second phase. The latter appears to have a carbonate content similar to that of the enamel mineral even when precipitated under the lowest partial pressure of CO2, suggesting that a molar content of about 0.3 of carbonate stabilizes the apatitic lattice. Based on the adopted stoichiometry of enamel mineral, Ca4.34 (HPO4).08 (CO3).29 (PO4)2.63 (OH).05, its solubility product constant was calculated as Ksp = 1.74 (+/- 0.081)x10(-6), expressed as the mean activity product.