Tang Yu Lung, Kim Jee-Hwan, Shim June-Sung, Kim Sunjai
Nonsan Yonsei Suite Dental Clinic, Nonsan, Chungnam, Republic of Korea.
Department of Prosthodontics, Yonsei University Dental Hospital, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
J Adv Prosthodont. 2017 Jun;9(3):152-158. doi: 10.4047/jap.2017.9.3.152. Epub 2017 Jun 19.
The purpose of this study was to evaluate the influence of different coping thicknesses and veneer ceramic cooling rates on the failure load of zirconia-ceramic crowns.
Zirconia copings of two different thicknesses (0.5 mm or 1.5 mm; n=20 each) were fabricated from scanning 40 identical abutment models using a dental computer-aided design and computer-aided manufacturing system. Zirconia-ceramic crowns were completed by veneering feldspathic ceramics under different cooling rates (conventional or slow, n=20 each), resulting in 4 different groups (CONV05, SLOW05, CONV15, SLOW15; n=10 per group). Each crown was cemented on the abutment. 300,000 cycles of a 50-N load and thermocycling were applied on the crown, and then, a monotonic load was applied on each crown until failure. The mean failure loads were evaluated with two-way analysis of variance (=.05).
No cohesive or adhesive failure was observed after fatigue loading with thermocycling. Among the 4 groups, SLOW15 group (slow cooling and 1.5 mm chipping thickness) resulted in a significantly greater mean failure load than the other groups (<.001). Coping fractures were only observed in SLOW15 group.
The failure load of zirconia-ceramic crowns was significantly influenced by cooling rate as well as coping thickness. Under conventional cooling conditions, the mean failure load was not influenced by the coping thickness; however, under slow cooling conditions, the mean failure load was significantly influenced by the coping thickness.
本研究旨在评估不同的内冠厚度和饰面陶瓷冷却速率对氧化锆陶瓷全冠破坏载荷的影响。
使用牙科计算机辅助设计和计算机辅助制造系统对40个相同的基牙模型进行扫描，制作两种不同厚度（0.5mm或1.5mm；每组n = 20）的氧化锆内冠。在不同冷却速率（常规或慢速，每组n = 20）下用长石质陶瓷进行饰面，完成氧化锆陶瓷全冠制作，从而得到4个不同的组（CONV05、SLOW05、CONV15、SLOW15；每组n = 10）。将每个全冠粘结在基牙上。对全冠施加50N载荷并进行300,000次热循环，然后对每个全冠施加单调载荷直至破坏。采用双向方差分析（α = 0.05）评估平均破坏载荷。
热循环疲劳加载后未观察到内聚性或粘结性破坏。在这4组中，SLOW15组（慢速冷却且内冠厚度为1.5mm）的平均破坏载荷显著高于其他组（P < 0.001）。仅在SLOW15组观察到内冠骨折。
氧化锆陶瓷全冠的破坏载荷受冷却速率和内冠厚度的显著影响。在常规冷却条件下，平均破坏载荷不受内冠厚度的影响；然而，在慢速冷却条件下，平均破坏载荷受内冠厚度的显著影响。
