Department of Mechanical Engineering, National Chung Cheng University, Chiayi, Taiwan 621, ROC.
J Biomech. 2009 Oct 16;42(14):2249-54. doi: 10.1016/j.jbiomech.2009.06.057. Epub 2009 Sep 12.
Tooth enamel is a hybrid organic-inorganic bionanocomposite comprised predominantly of enamel rods. Understanding the effects of anti-caries treatment on the biomechanical properties of these rods is essential in developing effective caries prevention strategies. Calcium fluoride-like deposits play an important role in caries prevention and their nanotribological properties have a direct effect upon their long-term effectiveness. Accordingly, this study utilizes a variety of techniques, namely nanoindentation, nanoscratch tests, nanowear tests and atomic force microscopy (AFM), to characterize the mechanical and tribological properties of single enamel rods before and after topical fluoride application. The results show that the CaF(2)-like deposits formed on the enamel surface following fluoride application increase the coefficient of friction of the enamel rods, but decrease their critical load and nanohardness. As a result, the nanowear depth of the treated enamel surface is around six times higher than that of the native enamel surface under an applied load of 300 microN. Following the removal of the surface deposits, however, the modulus of elasticity and wear depth of the underlying enamel surface are found to be similar to those of the original enamel surface. However, a notable increase in the surface roughness is observed.
牙釉质是一种主要由釉柱组成的混合有机-无机仿生纳米复合材料。了解防龋处理对这些棒的生物力学性能的影响，对于制定有效的防龋策略至关重要。氟化物样沉积物在防龋中起着重要作用，其纳米摩擦学特性直接影响其长期有效性。因此，本研究利用多种技术，即纳米压痕、纳米划痕试验、纳米磨损试验和原子力显微镜（AFM），在氟化物处理前后对单个牙釉质棒的力学和摩擦学性能进行了表征。结果表明，氟化物处理后在牙釉质表面形成的 CaF2 样沉积物增加了牙釉质棒的摩擦系数，但降低了其临界载荷和纳米硬度。因此，在 300μN 的外加载荷下，处理后的牙釉质表面的纳米磨损深度约为天然牙釉质表面的 6 倍。然而，在去除表面沉积物后，发现下面牙釉质表面的弹性模量和磨损深度与原始牙釉质表面相似。然而，表面粗糙度有显著增加。
