Department of Oral Rehabilitation, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand.
Department of Oral Rehabilitation, Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin, New Zealand.
J Prosthodont Res. 2020 Apr;64(2):120-127. doi: 10.1016/j.jpor.2019.05.007. Epub 2019 Jun 24.
To investigate the adhesion strength and bonding interface of layered porcelain to powdered cobalt-chromium (CoCr) processed by two different computer-aided manufacturing methods.
Sixteen specimens were manufactured from each of Three-dimensionally -printed/laser-sintered (LS) CoCr and milled pre-sintered (SM) CoCr. The specimens were layered with porcelain and 4-point bending was carried out. Nanoindentation was used to calculate changes in elastic modulus and hardness before and after porcelain firing along with adhesion energy. Fracture surface and microstructural changes were examined before and after porcelain firing observed using scanning electron microscopy.
The adhesion energy of the LS specimens bonded porcelain were higher than the SM specimens (P<0.05). Analysis of the fracture surfaces showed a predominantly adhesive mode of failure. Elastic-modulus and hardness of the CoCr specimens increased post porcelain firing. Examination using electron-backscatter diffraction (EBSD) showed a fine grain structure for both manufacturing methods. Significant localized changes in the crystal structure post firing were only observed at the surface of the SM specimens.
Both manufacturing methods showed regular microstructures prior to porcelain firing. Laser-sintered CoCr had stronger bonding to porcelain than milled pre-sintered CoCr and was also more stable microstructurally post-ceramic firing. However, both manufacturing methods were deemed to have satisfactory adhesion strength to porcelain. It was also found that increased hardness of CoCr had an inverse relationship with bonding strength. High strength porcelain bonding and stability following multiple ceramic firings indicate suitability for use of these CoCr materials with implant or tooth supported long-span frameworks.
研究两种不同计算机辅助制造方法加工的分层瓷与粉末钴铬（CoCr）的黏附强度和结合界面。
从三维打印/激光烧结（LS）CoCr 和铣削预烧结（SM）CoCr 中各制造 16 个样本。对样本进行分层上瓷，并进行四点弯曲试验。纳米压痕法用于计算瓷烧前后弹性模量和硬度的变化以及黏附能。使用扫描电子显微镜观察瓷烧前后的断裂表面和微观结构变化。
LS 样本结合瓷的黏附能高于 SM 样本（P<0.05）。断裂表面分析表明，主要为黏附失效模式。瓷烧后 CoCr 样本的弹性模量和硬度增加。电子背散射衍射（EBSD）检查显示两种制造方法均具有细晶粒结构。仅在 SM 样本表面观察到瓷烧后晶体结构的显著局部变化。
在瓷烧之前，两种制造方法均显示出规则的微观结构。与铣削预烧结 CoCr 相比，激光烧结 CoCr 与瓷的结合强度更强，并且在瓷烧后微观结构也更稳定。然而，两种制造方法都被认为具有令人满意的瓷结合强度。还发现 CoCr 的硬度增加与结合强度呈反比关系。高强度瓷结合和多次瓷烧后的稳定性表明这些 CoCr 材料适用于植入物或牙齿支持的长跨度框架。
