Department of Prosthodontics and Periodontics, Piracicaba Dental School, Campinas State University, São Paulo, Brazil.
Int J Oral Maxillofac Implants. 2012 Jul-Aug;27(4):833-8.
This study sought to determine an optimal postinsertion retorque protocol to maintain implantsuprastructure joint stability after being subjected to a 1-year in vitro masticatory simulation.
Ten mandibular implant-supported dentures were manufactured and 20 epoxy resin models were obtained for two fit levels: passive fit and misfit. Eight groups (n = 20) were created on the basis of vertical fit (passive or misfit) and prosthetic screw material (titanium or gold). The single-screw test was performed and the vertical misfit was quantified using an optical microscope. Loosening torque was measured after simulations of two types of clinical use: (1) 6 months of use, torque loosening, retightening, another 6 months of use, and loosening torque; and (2) 1 year of use followed by loosening torque. Data were analyzed by means of two-way analysis of variance and the Tukey test.
The factors of cycling time and condition use (fit level and screw type), as well the interaction between these factors, significantly influenced the loosening torque (P < .05). After 6 months and another 6 months of clinical use simulation, titanium screws showed higher loosening torque values than did gold screws for the same fit level (P < .05). After 1 year of clinical use simulation, titanium and gold screws in passively fit dentures showed higher loosening torque values than they did in misfit dentures (P < .05). The titanium screws presented a decrease in the loosening torque after 1 year in misfit dentures.
The stability of titanium screws was higher than that of gold screws after 6 months of simulation because of their lower plastic deformation. When the cycling time was analyzed, titanium screws were less stable after 1 year of simulation because of loss of torque in the presence of misfit.
本研究旨在确定一种最佳的植入体-上部结构连接体稳定性的后旋紧方案，以维持经过 1 年体外咀嚼模拟后的植入体。
制作了 10 个下颌种植体支持的义齿，并获得了 20 个环氧树脂模型，用于两种拟合水平：被动拟合和不匹配。根据垂直拟合（被动或不匹配）和修复螺丝材料（钛或金），创建了 8 个组（n = 20）。进行单螺丝测试，并使用光学显微镜定量测量垂直不匹配。模拟两种临床用途后测量松动扭矩：（1）使用 6 个月，扭矩松动，重新拧紧，再使用 6 个月，测量松动扭矩；（2）使用 1 年，然后测量松动扭矩。使用双向方差分析和 Tukey 检验对数据进行分析。
循环时间和使用条件（拟合水平和螺丝类型）的因素，以及这些因素之间的相互作用，显著影响松动扭矩（P <.05）。经过 6 个月和另外 6 个月的临床使用模拟，在相同的拟合水平下，钛螺丝比金螺丝显示出更高的松动扭矩值（P <.05）。经过 1 年的临床使用模拟，在被动拟合义齿中，钛和金螺丝显示出比不匹配义齿更高的松动扭矩值（P <.05）。在不匹配义齿中，钛螺丝在经过 1 年后出现松动扭矩降低的情况。
在模拟 6 个月后，由于钛螺丝的塑性变形较低，其稳定性高于金螺丝。当分析循环时间时，由于存在不匹配，钛螺丝在经过 1 年的模拟后稳定性降低。
