Abstract
Introduction: The proper screw preload delivery is affected by several factors, among which the coefficient of friction is responsible for affecting the delivery of proper amount of preload torque. It is believed that the delivered preload increases due to reduction in coefficient of friction.
Aims: The study aims to investigate maximum von Misses equivalent stresses generated within different parts of the assembly of. 4.1 mm and 10 mm long Straumann implant.
Material and Methods: The implant is inserted in place of the mandible first molar because of tightening screw. An analysis considered the screw surfaces as frictional and concluded that the frictional moment and the axial force opposed the advancement of the screw during its tightening. These loads were utilized for the implementation of three-dimensional finite element linear stress-strain analysis to compute the maximum equivalent stress generated within each part of the implant assembly to compare with the yield stress material of that part. The material used for retaining screw and the coefficient of friction between the screw surfaces were the variables of the study, including the abutment and implant surfaces.
Results and Discussion: Results were obtained for two assemblies having type III gold and Ti-6Al-4V titanium alloy screws each with 14 values of the friction coefficient.
Conclusion: The study concluded that stresses at the maximum tightening moment applied on the screw invariably decrease due to an increase in the coefficient of friction for all assembly parts.