Gehrke Peter, Dhom Günter, Brunner Jochen, Wolf Dietrich, Degidi Marco, Piattelli Adriano
Quintessence Int. 2006 Jan;37(1):19-26.
The purpose of this study was to determine the fracture strength of zirconium implant abutments and the torque required to unfasten the retaining screw before and after applying cyclic loading to the implant-abutment assembly. The dynamic behavior and stress distribution pattern of zirconium abutments were also evaluated.
Static and cyclic loading of 7 XiVE implants with straight Cercon zirconium abutments were simulated under worst-case conditions. Cyclic loading tests were performed via a servohydraulic dynamic testing machine at loads between 100 and 450 N, for up to 5 million loading cycles, at 15 Hz. The dynamic behavior of the zirconium abutments was analyzed by finite element modeling and Pro/Mechanica software, comparing van-der-Mises and maximum stress levels.
Cercon zirconium-ceramic abutments exhibited a maximum fracture strength of 672 N during static loading and 269 N at 800,000 to 5 million cycles runout point, and 403 N at 10,000 cycles runout point during cyclic loading. The mean torque value required to unfasten the abutment retaining screws after (initial) tightening was 21 Ncm +/- 1 and 20 Ncm +/- 1 (measurement accuracy +/- 2 Ncm) after loading with up to 5 million cycles respectively. Torque values decreased minimally and screw loosening did not occur. Within the limited number of test specimens (7), the difference was statistically significant (P = .015). FEM analysis displayed higher stress peaks up to 800 MPa at the cervical aspect of the zirconium abutment and at the apical third of its retaining screw at an external load of 250 N.
Within the limitations of this study, zirconium implant abutments exceeded the established values for maximum incisal bite forces reported in the literature and tightly fit into the titanium implant after several millions of loading cycles.
本研究旨在确定锆种植体基台的断裂强度以及在对种植体-基台组件施加循环载荷前后松开固位螺钉所需的扭矩。还评估了锆基台的动态行为和应力分布模式。
在最坏情况下模拟了7个带有直型Cercon锆基台的XiVE种植体的静态和循环载荷。通过伺服液压动态试验机在100至450 N的载荷下进行循环载荷试验，频率为15 Hz，加载次数高达500万次。通过有限元建模和Pro/Mechanica软件分析锆基台的动态行为，比较范德米塞斯应力和最大应力水平。
Cercon锆陶瓷基台在静态加载时的最大断裂强度为672 N，在80万至500万次循环的疲劳极限点为269 N，在循环加载1万次疲劳极限点时为403 N。在分别加载高达500万次循环后，（初始）拧紧后松开基台固位螺钉所需的平均扭矩值分别为21 Ncm±1和20 Ncm±1（测量精度±2 Ncm）。扭矩值下降极小且未发生螺钉松动。在有限数量的测试样本（7个）中，差异具有统计学意义（P = 0.015）。有限元分析显示，在250 N的外部载荷下，锆基台颈部和其固位螺钉根尖三分之一处的应力峰值高达800 MPa。
在本研究的局限性范围内，锆种植体基台超过了文献中报道的最大切牙咬合力的既定值，并且在数百万次加载循环后与钛种植体紧密贴合。
