MBLEM, Department of Engineering Science, University of Oxford, Parks Road, Oxford OX13PJ, UK.
Polytechnic Department of Engineering and Architecture (DPIA), University of Udine, Via delle Scienze 208, Udine 33100, Italy.
J Adv Res. 2020 Sep 6;29:167-177. doi: 10.1016/j.jare.2020.08.018. eCollection 2021 Mar.
In the past years, a significant amount of effort has been directed at the observation and characterisation of caries using experimental techniques. Nevertheless, relatively little progress has been made in numerical modelling of the underlying demineralisation process. The present study is the first attempt to provide a simplified calculation framework for the numerical simulation of the demineralisation process at the length scale of enamel rods and its validation by comparing the data with statistical analysis of experimental results. FEM model was employed to simulate a time-dependent reaction-diffusion equation process in which H ions diffuse and cause demineralisation of the enamel. The local orientation of the hydroxyapatite crystals was taken into account. Experimental analysis of the demineralising front was performed using advanced high-resolution synchrotron X-ray micro-Computed Tomography. Further experimental investigations were conducted by means of SEM and STEM imaging techniques. Besides establishing and validating the new modelling framework, insights into the role of the etchant solution pH level were obtained. Additionally, some light was shed on the origin of different types of etching patterns by simulating the demineralisation process at different etching angles of attack. The implications of this study pave the way for simulations of enamel demineralisation within different complex scenarios and across the range of length scales. Indeed, the framework proposed can incorporate the presence of chemical species other than H ions and their diffusion and reaction leading to dissolution and re-precipitation of hydroxyapatite. It is the authors' hope and aspiration that ultimately this work will help identify new ways of controlling and preventing caries.
在过去的几年中，人们投入了大量的精力来使用实验技术观察和描述龋齿。然而，在对潜在脱矿过程进行数值建模方面，进展相对较少。本研究首次尝试提供一个简化的计算框架，用于模拟釉柱长度尺度上的脱矿过程，并通过将数据与实验结果的统计分析进行比较来验证该框架。该研究采用有限元模型来模拟依赖时间的反应扩散方程过程，其中 H 离子扩散并导致牙釉质脱矿。同时，还考虑了羟基磷灰石晶体的局部取向。使用先进的高分辨率同步加速器 X 射线微计算机断层扫描对脱矿前沿进行了实验分析。此外，还通过 SEM 和 STEM 成像技术进行了进一步的实验研究。除了建立和验证新的建模框架外，该研究还深入了解了蚀刻溶液 pH 值水平的作用。此外，通过模拟不同蚀刻攻击角度下的脱矿过程，还揭示了不同类型蚀刻模式的起源。本研究为在不同复杂情况下和不同长度尺度范围内模拟牙釉质脱矿铺平了道路。实际上，所提出的框架可以纳入除 H 离子以外的其他化学物质的存在及其扩散和反应，从而导致羟基磷灰石的溶解和再沉淀。作者希望并期望这项工作最终将有助于确定控制和预防龋齿的新方法。
