Department of Prosthodontics and Materials Science, University Medical Center of the University of Mainz, Augustusplatz 2, 55131, Mainz, Germany.
Institute for Medical Biostatistics, Epidemiology and Informatics, University Medical Center of the University of Mainz, Obere Zahlbacher Straße 69, 55131, Mainz, Germany.
Int J Implant Dent. 2023 Mar 22;9(1):8. doi: 10.1186/s40729-023-00473-3.
An experimental approach was designed to measure the preload force, the coefficient of friction and the component of the tightening torque that is needed to surmount the thread-friction in an implant-abutment-screw complex that includes a carbon-coated screw. With the determined preload values the coefficient of friction was calculated.
25 unused complexes, containing an implant, an abutment and a carbon-coated titanium alloy abutment screw, were tested. A custom load frame with two load cells and associated electronics was used. The threads were not lubricated. All abutment screws were torqued ten times to 25 Ncm. The produced preload values and a force that was proportional to the thread-friction component of the tightening torque were recorded.
Mean preload values decreased significantly with the number of repetitions (p < 0.0001) from initially 329.9 N ± 33.3 (range 255.7 to 383.9) to 253.7 N ± 36.8 (range 200.1 to 332.5) for the last tightening procedure. The corresponding change in the calculated coefficient of friction was 0.33 ± 0.04 (range 0.28 to 0.43) to 0.44 ± 0.07 (range 0.32 to 0.56). For the thread-friction no corresponding trend for consecutive tightening repetitions could be noticed.
In the investigated implant-abutment units, repeated use of a coated abutment screw appears to increase the friction of the screw head and thereby decrease the preload. These results indicate that a pre-used coated implant-abutment-screw will fail reaching optimal screw preload.
设计了一种实验方法来测量预紧力、摩擦系数以及克服包含涂覆碳的螺钉的种植体-基台-螺钉复合体中的螺纹摩擦力所需的拧紧扭矩的分量。根据确定的预紧值计算摩擦系数。
测试了 25 个未使用的复合体，其中包含种植体、基台和涂覆碳的钛合金基台螺钉。使用带有两个测力传感器和相关电子设备的定制加载框架。螺纹未润滑。所有基台螺钉均以 25 Ncm 的扭矩拧紧 10 次。记录产生的预紧值和与拧紧扭矩的螺纹摩擦力分量成正比的力。
平均预紧值随着重复次数的增加而显著降低（p<0.0001），从最初的 329.9 N±33.3（范围 255.7 至 383.9）降至最后一次拧紧程序的 253.7 N±36.8（范围 200.1 至 332.5）。相应的计算摩擦系数变化为 0.33±0.04（范围 0.28 至 0.43）至 0.44±0.07（范围 0.32 至 0.56）。对于螺纹摩擦力，没有注意到连续拧紧重复次数的相应趋势。
在所研究的种植体-基台单元中，重复使用涂覆的基台螺钉似乎会增加螺钉头的摩擦力，从而降低预紧力。这些结果表明，预使用的涂覆种植体-基台-螺钉将无法达到最佳螺钉预紧力。
