Jaarda M J, Razzoog M E, Gratton D G
Department of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor 48109-1078.
Implant Dent. 1994 Spring;3(1):17-21. doi: 10.1097/00008505-199404000-00002.
The preload concept proposes that an optimal torque exists to which implant prosthetic retaining screws should be tightened. According to this theory, the preload prevents separation of implant components, thus protecting the screw from fracture. Recent research suggests that most implant-retained prostheses in function today were placed using improper preloads. The purpose of this investigation was to determine whether or not improper preloading of prosthetic implant-retaining screws would adversely affect their ultimate tensile strength. Fifteen Nobelpharma-slotted gold screws from one lot were tightened to 6, 10, and 15 N/cm with a torque gauge and ultimate tensile strength values determined. The procedure was duplicated using 15 Nobelpharma gold screws from another lot tightened to 0, 10, and 20 N/cm. Within each of the test groups, there was no significant difference in the ultimate tensile strength among the three preload torques. However, a paired t test (P = 0.005) determined that there was a significant difference between the two lots with respect to the ultimate tensile strength of the screws preloaded to 10 N/cm. Altering the preload torque applied to Nobelpharma gold-retaining screws does not affect their ultimate tensile strength. The ultimate tensile strength of the screws from the two lots differed, suggesting an unannounced change in component specifications.
预紧力概念提出，种植修复体固位螺钉存在一个最佳拧紧扭矩。根据这一理论，预紧力可防止种植体部件分离，从而保护螺钉不发生断裂。最近的研究表明，如今使用的大多数种植固定修复体在植入时预紧力使用不当。本研究的目的是确定种植修复体固位螺钉预紧力不当是否会对其极限抗拉强度产生不利影响。用扭矩计将同一批次的15颗诺贝尔pharma带槽金色螺钉分别拧紧至6 N/cm、10 N/cm和15 N/cm，并测定其极限抗拉强度值。使用另一批次的15颗诺贝尔pharma金色螺钉重复该过程，分别拧紧至0 N/cm、10 N/cm和20 N/cm。在每个测试组中，三种预紧扭矩下的极限抗拉强度没有显著差异。然而，配对t检验（P = 0.005）确定，在预紧至10 N/cm的螺钉的极限抗拉强度方面，两批螺钉之间存在显著差异。改变施加在诺贝尔pharma金色固位螺钉上的预紧扭矩不会影响其极限抗拉强度。两批螺钉的极限抗拉强度不同，表明部件规格存在未公布的变化。
