Grimm Jack R, Renteria Cameron, Mukhopadhyay Semanti, Devaraj Arun, Arola Dwayne D
Department of Materials Science and Engineering, University of Washington, Seattle, WA USA.
Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA USA.
Commun Mater. 2024;5(1):270. doi: 10.1038/s43246-024-00709-8. Epub 2024 Dec 19.
Dental enamel is subjected to a lifetime of de- and re-mineralization cycles in the oral environment, the cumulative effects of which cause embrittlement with age. However, the understanding of atomic scale mechanisms of dental enamel aging is still at its infancy, particularly regarding where compositional differences occur in the hydroxyapatite nanocrystals and what underlying mechanisms might be responsible. Here, we use atom probe tomography to compare enamel from a young (22 years old) and a senior (56 years old) adult donor tooth. Findings reveal that the concentration of fluorine is elevated in the shells of senior nanocrystals relative to young, with less significant differences between the cores or intergranular phases. It is proposed that the embrittlement of enamel is driven, at least in part, by the infusion of fluorine into the nanocrystals and that the principal mechanism is de- and re-mineralization cycles that preferentially erode and rebuild the nanocrystals shells.
牙釉质在口腔环境中会经历一生的脱矿和再矿化循环，其累积效应会导致随着年龄增长而变脆。然而，对牙釉质老化的原子尺度机制的理解仍处于起步阶段，特别是关于羟基磷灰石纳米晶体中成分差异出现在何处以及可能是什么潜在机制导致的。在这里，我们使用原子探针断层扫描技术来比较一颗年轻（22岁）和一颗年长（56岁）成人供体牙齿的牙釉质。研究结果表明，与年轻纳米晶体相比，年长纳米晶体外壳中的氟浓度升高，而核心或晶间相之间的差异不太显著。有人提出，牙釉质的脆化至少部分是由氟注入纳米晶体驱动的，主要机制是优先侵蚀和重建纳米晶体外壳的脱矿和再矿化循环。
