Wang Shujie, Zhang Jiawen, Ma Jing, Yang Hui, Shao Xiaoqing, Su Mu, Zhou Zhenlei, Li Zhen
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.
J Biomed Mater Res B Appl Biomater. 2021 Aug;109(8):1230-1238. doi: 10.1002/jbm.b.34784. Epub 2020 Dec 22.
Dental caries is one of the most common disorders in dentistry. Typically, it is caused by the dissolution of the tooth mineral due to cariogenic organisms. Bioapatite is vulnerable to acid-etching ascribed to a variety of substitutions. This study applied Pb cations to probe the dissolution of synthetic carbonated hydroxylapatite (CHAp) in the acidic environment induced by Enterobacter sp. It indicated a decreasing tendency of crystallite size (from ∼400 nm to 10-20 nm) during gradual incorporation of carbonate (from 2.5 to 13.8 wt %). Meanwhile, the shape of CHAp crystals was transformed from elongated to plate-like. Addition of Enterobacter sp. enhanced P release from CHAp (especially for the CHAp with ∼8 wt % CO ) around 10 times. Moreover, the bacterium provided a moderately acidic environment to cause more formation of stable pyromorphite over other Pb-minerals, for example, Pb (PO ) , and PbCO . Then, transmission electron microscopy-energy dispersive X-Ray spectroscopy mapping successfully confirmed the Pb labeling on the newly formed phosphate mineral as Pb (with high-atomic weight) has strong signal under electron microscopy. This study therefore elucidated that Pb labeling has a bright future to explore the degradation of tooth mineral by microorganisms, as well as to evaluate the resistance of calcium phosphate dental restorative materials.
龋齿是牙科领域最常见的病症之一。通常，它是由致龋生物导致牙齿矿物质溶解引起的。由于存在多种替代物，生物磷灰石易受酸蚀。本研究应用铅阳离子来探究合成碳酸羟基磷灰石（CHAp）在肠杆菌属诱导的酸性环境中的溶解情况。研究表明，在碳酸盐逐渐掺入（从2.5 wt%至13.8 wt%）过程中，微晶尺寸呈现减小趋势（从约400 nm减小至10 - 20 nm）。同时，CHAp晶体形状从细长形转变为板状。添加肠杆菌属使CHAp中磷的释放增强（特别是对于含约8 wt% CO₃²⁻的CHAp），增强了约10倍。此外，该细菌提供了一个中等酸性环境，相比于其他铅矿物，例如Pb₃(PO₄)₂和PbCO₃，能促使更多稳定的磷氯铅矿形成。然后，透射电子显微镜 - 能量色散X射线光谱映射成功证实了新形成的磷酸盐矿物上的铅标记，因为铅（具有高原子量）在电子显微镜下有很强的信号。因此，本研究阐明铅标记在探索微生物对牙齿矿物质的降解以及评估磷酸钙牙科修复材料的抗性方面具有广阔前景。
