Formation of Brushite, Monetite and Whitlockite during Equilibration of Human Enamel with Acid Solutions at 37°C
Formation of Brushite, Monetite and Whitlockite during Equilibration of Human Enamel with Acid Solutions at 37°C
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37°C 下人体牙釉质与酸溶液平衡过程中透钙磷石、三斜磷钙石和钙磷矿的形成
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
F. K. Wahab
中科院分区：
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作者：
R. Shellis;B. Heywood;F. K. Wahab
用显微镜检查5个粉末状人牙釉质样品的残留物，每个样品在37°C下用17或4 mmol/l磷酸进行5次连续平衡。用17 mmol/l酸，在1次平衡后发现透钙磷石和三斜磷钙石，但在进一步平衡后，透钙磷石不再存在，三斜磷钙石晶体的丰度增加。与在25 °C下不形成三斜磷钙石的类似低pH系统相比，三斜磷钙石的形成可能导致该系统的亚稳定性较低。用4 mmol/l酸平衡后，既不存在透钙磷石，也不存在三斜磷钙石。通过透射电子显微镜和电子衍射在所有残留物中鉴定了白磷钙石。在4 mmol/l体系中，Ca_9Mg（HPO_4）（PO_4）_6的离子活度积（IMwh）在1-3次平衡后趋于稳定，平均值为3.6（± 0.51SE）·10 ~（-10）5，这可能反映了该固体的饱和状态。对于17 mmol/l系统，较高的IMWH值和三斜磷钙石的过饱和度被解释为由于白磷钙石和三斜磷钙石的缓慢晶体生长而导致的持久亚稳定性的证据。它的结论是，既不透钙磷石，也不三斜磷钙石是可能形成的龋损内，但结果是一致的，与已知的关联白磷钙石与龋齿。
The residues of 5 samples of powdered human enamel, each subjected to 5 sequential equilibrations at 37°C with either 17 or 4 mmol/l phosphoric acid, were examined microscopically. With 17 mmol/l acid, both brushite and monetite were found after 1 equilibration but, after further equilibrations, brushite was no longer present and the abundance of monetite crystals increased. Formation of monetite probably contributed to the lower metastability of this system compared to similar low-pH systems at 25 °C, where monetite does not form. Neither brushite nor monetite were present after equilibration with 4 mmol/l acid. Whitlockite was identified by transmission electron microscopy and electron diffraction in all residues. In the 4 mmol/l systems, the ionic activity product (IMwh) for magnesium whitlockite, Ca9Mg(HPO4)(PO4)6, became constant after 1–3 equilibrations, at a mean value of 3.6 ( ± 0.51 SE)·10––105, which may reflect saturation with respect to this solid. For the 17 mmol/l systems, higher values of IMWH, and supersaturation with respect to monetite, were interpreted as evidence for persistent metastability due to slow crystal growth of whitlockite and monetite. It is concluded that neither brushite nor monetite are likely to form within carious lesions, but the results are consistent with the known association of whitlockite with caries.