Ricciardi Coppedê Abílio, de Mattos Maria da Glória Chiarello, Rodrigues Renata Cristina Silveira, Ribeiro Ricardo Faria
Department of Dental Materials and Prostheses, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Clin Oral Implants Res. 2009 Jun;20(6):624-32. doi: 10.1111/j.1600-0501.2008.01690.x. Epub 2009 Mar 4.
Internal tapered connections were developed to improve biomechanical properties and to reduce mechanical problems found in other implant connection systems. The purpose of this study was to evaluate the effects of mechanical loading and repeated insertion/removal cycles on the torque loss of abutments with internal tapered connections.
Sixty-eight conical implants and 68 abutments of two types were used. They were divided into four groups: groups 1 and 3 received solid abutments, and groups 2 and 4 received two-piece abutments. In groups 1 and 2, abutments were simply installed and uninstalled; torque-in and torque-out values were measured. In groups 3 and 4, abutments were installed, mechanically loaded and uninstalled; torque-in and torque-out values were measured. Under mechanical loading, two-piece abutments were frictionally locked into the implant; thus, data of group 4 were catalogued under two subgroups (4a: torque-out value necessary to loosen the fixation screw; 4b: torque-out value necessary to remove the abutment from the implant). Ten insertion/removal cycles were performed for every implant/abutment assembly. Data were analyzed with a mixed linear model (P< or =0.05).
Torque loss was higher in groups 4a and 2 (over 30% loss), followed by group 1 (10.5% loss), group 3 (5.4% loss) and group 4b (39% torque gain). All the results were significantly different. As the number of insertion/removal cycles increased, removal torques tended to be lower. It was concluded that mechanical loading increased removal torque of loaded abutments in comparison with unloaded abutments, and removal torque values tended to decrease as the number of insertion/removal cycles increased.
内锥连接的设计旨在改善生物力学性能，并减少其他种植体连接系统中出现的机械问题。本研究的目的是评估机械加载和重复插入/取出循环对带有内锥连接的基台扭矩损失的影响。
使用了68颗锥形种植体和两种类型的68个基台。它们被分为四组：第1组和第3组使用实心基台，第2组和第4组使用两件式基台。在第1组和第2组中，基台仅进行安装和卸载操作，并测量旋入扭矩和旋出扭矩值。在第3组和第4组中，基台进行安装、机械加载然后卸载，并测量旋入扭矩和旋出扭矩值。在机械加载下，两件式基台通过摩擦力锁定在种植体内；因此，第4组的数据被分类为两个亚组（4a：松开固定螺钉所需的旋出扭矩值；4b：将基台从种植体上取下所需的旋出扭矩值）。对每个种植体/基台组件进行10次插入/取出循环操作。数据采用混合线性模型进行分析（P≤0.05）。
第4a组和第2组的扭矩损失较高（损失超过30%），其次是第1组（损失10.5%）、第3组（损失5.4%）和第4b组（扭矩增加39%）。所有结果均有显著差异。随着插入/取出循环次数的增加，取出扭矩趋于降低。得出的结论是，与未加载的基台相比，机械加载增加了加载基台的取出扭矩，并且取出扭矩值倾向于随着插入/取出循环次数的增加而降低。
