Alao Abdur-Rasheed, Stoll Richard, Song Xiao-Fei, Abbott John R, Zhang Yu, Abduo Jaafar, Yin Ling
Mechanical Engineering, College of Science and Engineering, James Cook University, Townsville QLD 4811, Australia.
Restorative Dentistry, College of Medicine and Dentistry, James Cook University, Cairns QLD 4870, Australia.
J Mech Behav Biomed Mater. 2017 Oct;74:251-260. doi: 10.1016/j.jmbbm.2017.06.015. Epub 2017 Jun 15.
This paper studied surface fracture, roughness and morphology, phase transformations, and material removal mechanisms of lithium metasilicate/disilicate glass ceramics (LMGC/LDGC) in CAD/CAM-milling and subsequent surface treatments. LMGC (IPS e.max CAD) blocks were milled using a chairside dental CAD/CAM milling unit and then treated in sintering, polishing and glazing processes. X-ray diffraction was performed on all processed surfaces. Scanning electron microscopy (SEM) was applied to analyse surface fracture and morphology. Surface roughness was quantitatively characterized by the arithmetic average surface roughness R and the maximum roughness R using desktop SEM-assisted morphology analytical software. The CAD/CAM milling induced extensive brittle cracks and crystal pulverization on LMGC surfaces, which indicate that the dominant removal mechanism was the fracture mode. Polishing and sintering of the milled LMGC lowered the surface roughness (ANOVA, p < 0.05), respectively, while sintering also fully transformed the weak LMGC to the strong LDGC. However, polishing and glazing of LDGC did not significantly improve the roughness (ANOVA, p > 0.05). In comparison of all applied fabrication process routes, it is found that CAD/CAM milling followed by polishing and sintering produced the smoothest surface with R = 0.12 ± 0.08µm and R = 0.89 ± 0.26µm. Thus it is proposed as the optimized process route for LMGC/LDGC in dental restorations. This route enables to manufacture LMGC/LDGC restorations with cost effectiveness, time efficiency, and improved surface quality for better occlusal functions and reduced bacterial plaque accumulation.
本文研究了偏硅酸锂/二硅酸锂玻璃陶瓷（LMGC/LDGC）在CAD/CAM铣削及后续表面处理过程中的表面断裂、粗糙度和形貌、相变以及材料去除机制。使用椅旁牙科CAD/CAM铣削单元对LMGC（IPS e.max CAD）块体进行铣削，然后进行烧结、抛光和上釉处理。对所有加工表面进行X射线衍射分析。应用扫描电子显微镜（SEM）分析表面断裂和形貌。使用台式SEM辅助形貌分析软件，通过算术平均表面粗糙度R和最大粗糙度R对表面粗糙度进行定量表征。CAD/CAM铣削在LMGC表面引发了大量脆性裂纹和晶体粉碎，这表明主要的去除机制是断裂模式。铣削后的LMGC进行抛光和烧结分别降低了表面粗糙度（方差分析，p < 0.05），同时烧结还将弱的LMGC完全转变为强的LDGC。然而，LDGC的抛光和上釉并没有显著改善粗糙度（方差分析，p > 0.05）。在比较所有应用的制造工艺路线时，发现先进行CAD/CAM铣削，然后进行抛光和烧结可产生最光滑的表面，R = 0.12 ± 0.08µm，R = 0.89 ± 0.26µm。因此，它被提议作为牙科修复中LMGC/LDGC的优化工艺路线。该路线能够制造出具有成本效益、时间效率且表面质量得到改善的LMGC/LDGC修复体，以实现更好的咬合功能并减少细菌菌斑积聚。
