Cibirka R M, Nelson S K, Lang B R, Rueggeberg F A
School of Dentistry, Medical College of Georgia, Augusta, Ga 30912, USA.
J Prosthet Dent. 2001 Mar;85(3):268-75. doi: 10.1067/mpr.2001.114266.
This study examined potential differences in detorque values of abutment screws after fatigue testing when the dimensions between external implant hexagon and internal abutment hexagon were altered or the implant external hexagonal shape was eliminated.
Three subsets (N = 10) of NobelBiocare implants were assessed: (1) standard external hexagon (R), (2) modified hexagon (M), and (3) circular (C) platform geometry. Thirty Procera machined abutments with 25-degree angulated loading platforms were manufactured. Abutments were retained with gold Unigrip abutment screws tightened to 32 N/cm with an electronic torque controller. Vertical scribes across the implant-abutment interface allowed longitudinal displacement evaluation. A carousel-type fatigue testing device delivered dynamic loading forces between 20 and 200 N for 5,000,000 cycles, or the approximate equivalent of 5 years in vivo mastication, through a piston to the abutment platform. Macroscopic and radiographic examination of the implant/abutment specimens was performed. The abutment screws were removed and the detorque values recorded. Bearing surfaces were examined microscopically.
No abutment looseness or longitudinal displacements at the implant-abutment interface were noted. Radiographic examination demonstrated no indication of screw bending or displacement. The mean detorque values for R, M, and C were 14.40 +/- 1.84 N/cm, 14.70 +/- 1.89 N/cm, and 16.40 +/- 2.17 N/cm, respectively. The analysis of variance demonstrated significant differences between only designs R and C (P=.031).
Increasing the vertical height, or degree of fit tolerance, between the implant external hexagon and the abutment internal hexagon or completely eliminating the implant external hexagon did not produce a significant effect on the detorque values of the abutment screws after 5,000,000 cycles in fatigue testing, or the equivalent of 5 years' of mastication for the implant/abutment specimens evaluated.
本研究探讨了在疲劳测试后，当种植体外六角与基台内六角之间的尺寸改变或种植体外六角形状被消除时，基台螺钉拆卸扭矩值的潜在差异。
评估了三组（每组n = 10）诺贝尔生物公司的种植体：（1）标准外六角（R），（2）改良六角（M），以及（3）圆形（C）平台几何形状。制作了30个带有25度角加载平台的Procera加工基台。基台用金色Unigrip基台螺钉固定，使用电子扭矩控制器将其拧紧至32 N/cm。在种植体 - 基台界面上的垂直划痕用于纵向位移评估。一个转盘式疲劳测试装置通过活塞向基台平台施加20至200 N的动态加载力，持续5,000,000次循环，或相当于体内5年的咀嚼次数。对种植体/基台标本进行了宏观和影像学检查。移除基台螺钉并记录拆卸扭矩值。对承载表面进行了显微镜检查。
在种植体 - 基台界面未观察到基台松动或纵向位移。影像学检查未显示螺钉弯曲或位移的迹象。R、M和C组的平均拆卸扭矩值分别为14.40±1.84 N/cm、14.70±1.89 N/cm和16.40±2.17 N/cm。方差分析表明仅设计R和C之间存在显著差异（P = 0.031）。
对于所评估的种植体/基台标本，在疲劳测试5,000,000次循环（相当于5年咀嚼）后，增加种植体外六角与基台内六角之间的垂直高度或配合公差程度，或完全消除种植体外六角，对基台螺钉的拆卸扭矩值没有显著影响。
