Formation of Fluorohydroxyapatite with Silver Diamine Fluoride
Formation of Fluorohydroxyapatite with Silver Diamine Fluoride
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DOI：
10.1177/0022034517709738
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发表时间：
2017-09-01
影响因子：
7.6
通讯作者：
Chu, C. H.
中科院分区：
文献类型：
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作者：
Mei, M. L.;Nudelman, F.;Chu, C. H.
二胺氟化银(SDF)被发现可以促进再矿化和硬化龋损。羟基磷灰石结晶是再矿化的关键过程；然而，SDF在晶体形成中的作用尚不清楚。设计了不同浓度(0.38、1.52、2.66、3.80 mg/mLSDF)的磷酸钙对磷灰石晶体成核和生长的影响。两个对照组也准备了磷酸钙(缓冲溶液中的CaCl2中心点2H(2)O+K2HPO4)和SDF(缓冲溶液中的Ag[NH3](2)F)。在37℃孵育24 h后，用明场透射电子显微镜和电子衍射仪观察晶体的形态和结构。用粉末X射线衍射法测定了所得晶体的晶胞参数。用拉曼显微镜分析了磷酸盐基团的振动和转动模式。透射电子显微镜和选区电子衍射仪证实，SDF基团中析出的所有固体都是结晶的，并且晶体尺寸百分比的增加与SDF的浓度成正相关。粉末X-射线衍射图表明，所有SDF基团都形成了氟羟基磷灰石和氯化银。与磷酸钙对照相比，SDF基团的晶胞沿a方向收缩，而不是c方向收缩，表明少量的局部氟离子取代了羟基磷灰石晶体中的羟基阴离子。拉曼光谱进一步证明了这一点，它显示了所有SDF基团的磷酸盐带的上场移动，证实了磷酸盐官能团的化学环境确实发生了变化。结果表明，SDF与钙、磷离子反应生成氟羟基磷灰石。这种溶解度降低的氟羟基磷灰石的优先析出可能是SDF抑制龋损的主要因素之一。
Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared-calcium phosphate (CaCl2 center dot 2H(2)O + K2HPO4 in buffer solution) and SDF (Ag[NH3](2) F in buffer solution). After incubation at 37 degrees C for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with reduced solubility could be one of the main factors for arrest of caries lesions treated with SDF.