Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, Sydney, NSW, Australia.
Caries Res. 2010;44(2):101-7. doi: 10.1159/000286214. Epub 2010 Feb 18.
The aim of this paper was to characterise the mechanical properties (MPs) and microstructural features of natural enamel white spot lesions (WSLs) using nano-indentation. Five natural WSLs from 4 extracted sound premolar teeth were cross-sectioned. Elastic modulus and hardness were measured systematically across the WSLs at intervals of 25 and 50 microm. The WSLs showed a large reduction in MPs compared to sound counterpart: elastic modulus was up to 83% lower (77.0 +/- 2.2 to 13.4 +/- 2.1 GPa) and hardness up to 91% lower (3.39 +/- 0.41 to 0.29 +/- 0.07 GPa). The intact surface layer above WSLs had less than 34% reduction in MPs. Detailed MP measurements were mapped as two-dimensional contour plots. Typically, WSLs displayed steep MP gradients at the lesion boundary and more uniform MPs with isolated variations in the lesion body. Despite the large reduction in MPs, the microstructure of WSLs remained intact. We postulate that loss of mineral and change of the hierarchical microstructure at the crystallite level contributed to the overall MPs of WSLs.
本文旨在通过纳米压痕技术来描述天然釉质白斑（WSL）的力学性能（MPs）和微观结构特征。从 4 颗拔出的健康前磨牙中选取 5 个天然 WSL 进行横截，在 25μm 和 50μm 间隔处对 WSL 进行系统的弹性模量和硬度测量。与正常釉质相比，WSL 的 MPs 明显降低：弹性模量降低了 83%（77.0±2.2 至 13.4±2.1GPa），硬度降低了 91%（3.39±0.41 至 0.29±0.07GPa）。WSL 上方的完整表面层的 MPs 减少不到 34%。详细的 MPs 测量结果以二维等高线图显示。通常，WSL 在病变边界处显示出陡峭的 MPs 梯度，而在病变体中则显示出更均匀的 MPs 和孤立的变化。尽管 MPs 大量减少，但 WSL 的微观结构仍保持完整。我们推测，晶体水平的矿物质损失和层次微观结构的变化导致了 WSL 的整体 MPs 变化。
