Frictional wear of stud implant overdenture abutments after 2 years of in vitro simulated function

Progressive wear of the components of an implant-supported overdenture can lead to loss of denture retention, which affects masticatory function and the patient's quality of life. The primary objective of this in vitro study was to investigate frictional wear in a type of commonly used abutment and thereby estimate the general clinical lifespan of a typical stud abutment and establish a protocol for replacement. Therefore, simulated overdenture insertions and removals equivalent to 2 years of overdenture use were performed to evaluate surface changes in the metal stud abutment component. A digital caliper, scanning electron micrographs taken at ×500 magnification, and profilometer data were used to determine the wear rate and surface roughness. A universal testing machine was used to measure retention load force with 4 clear male nylon inserts (5.0-lb retention) during 2160 insertion and removal cycles. The results showed that with a 6-month replacement program for clear male nylon inserts, the frictional wear on the titanium nitride coating of abutments placed at a 0° position resulted in a decrease of up to 50% in removal forces of the inserts after a simulated 2 years of wear. The combination of wear of the titanium nitride coating and the decrease in retention load values suggests that stud abutments should be replaced after 2 years of use for optimal retention.