Objective: To provide a reference for a suitable alternative treatment choice for implant-supported prostheses, and to explore the influence of 3 types of prosthetic material on the stress distribution around implant. Methods: The implant-abutment analogs were embedded individually into photoelastic resin blocks, which were medical pure titanium castings reproducing the surface and outline of implant (diameter 4.3 mm, length 11.5 mm) and esthetic abutment (regular profile, 1 mm). The prostheses were divided into 3 groups according to the type of prosthetic material. Each group consisted of 5 samples. The samples of composite resin ceramic and zirconia group were milled by chair-side computer aided design and computer aided manufacture (CAD/CAM) system. The samples of porcelain-fused-to-metal crown group were made manually and a pre-arranged silicone rubber impression of CAD/CAM crown would guide to shape the veneer porcelain. Each set was submitted to a 300 N compressive load axially or obliquely (75°). The stress value in the peri-implant bone at the level of the neck, neck1/3, middle1/3 and root1/3 of the sections (0.5, 1.5, 2.5, 3.5 mm) from implant was analyzed by digital photoelasticity, and the stress cushioning effect of 3 types of prosthetic material was comprehensively evaluated. Results: The time spent reaching the stress peak of composite resin ceramic group [(1.58±0.08) s, axially; (2.75±0.21) s, obliquely] was larger than that of the zirconia group [(1.40±0.12) s, axially; (2.30±0.25) s, obliquely] (P<0.05) under the same download mode. Although there were no significant differences in equivalent stress values of the measurement points among the three groups (P>0.05), a downward trend of equivalent stress values of composite resin ceramic group was observed compared to zirconia group, regardless of load type. When loaded obliquely, the highest degree of stress concentration at the level of the neck of implant were found in the porcelain-fused-to-metal crown group. Conclusions: Within the limitations of this study, composite resin ceramic was more beneficial to the biomechanical behavior of implant in stress buffer compared to zirconia.
目的： 通过光弹模型分析3种单冠对种植体周围骨应力分布的影响，以期为种植修复单冠的材料选择提供参考。 方法： 使用医用纯钛仿照种植体（Nobel Replace，直径为4.3 mm，长度为11.5 mm）及美观基台（标准型，穿龈高度1 mm）铸造种植体-基台一体化试件，包埋于光弹模型中。使用椅旁计算机辅助设计与辅助制作系统完成树脂陶瓷冠和氧化锆全冠的单冠制作，对切削成形的冠部形态制取硅橡胶阴模，辅助金属烤瓷冠的饰瓷堆塑。制作树脂陶瓷冠组、氧化锆全冠组和金属烤瓷冠组光弹模型试件，每组5个。对3组光弹模型分别进行垂直及斜向75°加载（300 N），通过数字光弹法分析3组种植体周围骨内不同观测面（0.5、1.5、2.5、3.5 mm）上颈部、颈1/3、中1/3、根1/3及根尖共5个观测点的应力，评价3种单冠受力后的应力缓冲作用。 结果： 相同加载模式下，树脂陶瓷冠组种植体周围骨应力到达峰值的时间[垂直和斜向加载分别为（1.58±0.08）和（2.75±0.21）s]均显著大于氧化锆全冠组[垂直和斜向加载分别为（1.40±0.12）和（2.30±0.25）s]（P<0.05）；3组种植体周围相同观测点的等效应力值间差异均无统计学意义（P>0.05），但相比氧化锆全冠组，树脂陶瓷冠组各观测点的等效应力值均呈减小趋势。斜向加载时金属烤瓷冠组种植体颈部应力集中程度最明显。 结论： 与氧化锆相比，复合树脂陶瓷对种植体周围骨内应力的缓冲作用更具优势。.
Keywords: Crowns; Dental implants; Dental stress analysis.