Methods: Three different types of implant-abutment connections were selected for this study. Sample A: 1.5 mm deep internal hex corresponding to a lead-in bevel, sample B: a tri-channel internal connection, and sample C: internal Morse taper with 110 degrees of tapering and 6 anti-rotational grooves. Four types of loading conditions were simulated in a finite element model and the maximum Von Mises stress set as output variables.
Results: The maximum stress concentration at the inner surface of the fixtures was higher than the stress value in bone in all of the samples. Stress values in sample B were the lowest amongst all of the models. Any alterations in amount and direction of the 100 N axial load resulted in an increase in fixture surfaces stress. Overall, the highest amount of stress (112 MPa) was detected in sample C at the inner surface of the fixture under a non axial load of 300 N.
Conclusions: Stress concentration could be reduced when the internal surface area increased. Creating three or six stops in the internal surface of the fixtures resulted in a stress reduction.