Mohammed N R, Mneimne M, Hill R G, Al-Jawad M, Lynch R J M, Anderson P
Barts and The London School of Medicine and Dentistry, Queen Mary University, Dental Physical Sciences Unit, Centre for Oral Growth and Development, London E1 4NS, United Kingdom.
Barts and The London School of Medicine and Dentistry, Queen Mary University, Dental Physical Sciences Unit, Centre for Oral Growth and Development, London E1 4NS, United Kingdom.
J Dent. 2014 Sep;42(9):1096-104. doi: 10.1016/j.jdent.2014.04.014. Epub 2014 May 9.
Zinc salts are formulated into oral health products as antibacterial agents, yet their interaction with enamel is not clearly understood. The aim was to investigate the effect of zinc concentration [Zn(2+)] on the in vitro demineralization of enamel during exposure to caries-simulating conditions. Furthermore, the possible mechanism of zinc's action for reducing demineralization was determined.
Enamel blocks and synthetic hydroxyapatite (HAp) were demineralized in a range of zinc-containing acidic solutions (0-3565ppm [Zn(2+)]) at pH 4.0 and 37°C. Inductively coupled-plasma optical emission spectroscopy (ICP-OES) was used to measure ion release into solution. Enamel blocks were analysed by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and HAp by X-ray diffraction (XRD) and neutron diffraction (ND).
ICP-OES analysis of the acidic solutions showed a decrease in [Ca(2+)] and [PO4(3-)] release with increasing [Zn(2+)]. FTIR revealed a α-hopeite (α-Zn3(PO4)2.4H2O)-like phase on the enamel surfaces at >107ppm [Zn(2+)]. XRD and ND analysis confirmed a zinc-phosphate phase present alongside the HAp.
This study confirms that zinc reduces enamel demineralization. Under the conditions studied, zinc acts predominantly on enamel surfaces at PO4(3-) sites in the HAp lattice to possibly form an α-hopeite-like phase.
These results have a significant implication on the understanding of the fundamental chemistry of zinc in toothpastes and demonstrate its therapeutic potential in preventing tooth mineral loss.
锌盐作为抗菌剂被添加到口腔卫生产品中，但其与牙釉质的相互作用尚不清楚。本研究旨在探讨锌离子浓度[Zn(2+)]对模拟龋环境下牙釉质体外脱矿的影响。此外，还确定了锌减少脱矿作用的可能机制。
将牙釉质块和合成羟基磷灰石（HAp）在一系列含锌酸性溶液（0-3565ppm [Zn(2+)]）中于pH 4.0和37°C条件下进行脱矿。采用电感耦合等离子体发射光谱法（ICP-OES）测量离子释放到溶液中的情况。通过衰减全反射傅里叶变换红外光谱法（ATR-FTIR）分析牙釉质块，通过X射线衍射（XRD）和中子衍射（ND）分析HAp。
ICP-OES对酸性溶液的分析表明，随着[Zn(2+)]的增加，[Ca(2+)]和[PO4(3-)]的释放量减少。FTIR显示，当[Zn(2+)]>107ppm时，牙釉质表面出现类似α-磷锌矿（α-Zn3(PO4)2·4H2O）的相。XRD和ND分析证实，在HAp旁边存在磷酸锌相。
本研究证实锌可减少牙釉质脱矿。在所研究的条件下，锌主要作用于HAp晶格中PO4(3-)位点的牙釉质表面，可能形成类似α-磷锌矿的相。
这些结果对理解牙膏中锌的基础化学性质具有重要意义，并证明了其在预防牙齿矿物质流失方面的治疗潜力。
