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Updated: Feb 19, 2026

An Improved Mechanical Testing Method to Assess Bone-implant Anchorage
Published on: February 10, 2014
Preload, Coefficient of Friction, and Thread Friction in an Implant-Abutment-Screw Complex
Purpose:
To examine the screw preload, coefficient of friction (COF), and tightening torque needed to overcome the thread friction of an implant-abutment-screw complex.
Materials And Methods:
In a customized load frame, 25 new implant-abutment-screw complexes including uncoated titanium alloy screws were torqued and untorqued 10 times each, applying 25 Ncm.
Results:
Mean preload values decreased significantly from 209.8 N to 129.5 N according to the number of repetitions. The overall COF increased correspondingly. There was no comparable trend for the thread friction component.
Conclusion:
These results suggest that the application of a used implant-abutment-screw complex may be unfavorable for obtaining optimal screw preload.
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