Original vs compatible stock abutment- implant connection: An in vitro analysis of the internal accuracy and mechanical fatigue behaviour

Purpose: To assess the internal accuracy and mechanical behaviour under cyclic loading after artificial aging of implantsupported crowns restored with original stock abutments and two compatible non-original stock abutments. Methods: Forty-eight original internal hexagon connection implants were connected to different stock abutments. The samples were divided into three groups depending on the manufacturer of the abutment components (one original, two non- originals). Firstly, samples were cross-sectioned and observed by using Scanning Electron Microscope (SEM) to evaluate the internal accuracy in three different implant-abutment interface locations (platform, internal and screw). Further, cyclic fatigue loading was carried out according to the ISO Norm 14801 using dynamic testing machine under sinusoidal loads for 2,000,000 cycles at test frequencies of 2 Hz in air after thermocycling with 10,000 cycles at 5 degrees C and 55 degrees C in artificial saliva for aging simulation. Results: Original abutment components presented the highest percentage of surface with tight contact with the implant in the three implant-abutment interfaces studied. Additionally, original configuration showed highest fatigue limit value and fatigue strength exponent (280 N and -0.054) than non-original 1 (225 N and -0.109) and non-original 2 (200 N and -0.101). Conclusion: Original abutment components provide better fit and mechanical results under cyclic loading than nonoriginal configurations. The results obtained in this study seem to suggest that the use of the original stock abutments to implants leads to a more homogeneous load distribution between the components that can influence the long-term success of the restorations.