Dynamic fatigue resistance of implant-abutment junction in an internally notched morse-taper oral implant:: influence of abutment design

Purpose: To compare dynamic fatigue resistance of one- and two-piece abutments connected to internally notched morse-taper oral implants. Material and methods: Sixteen synOcta(R) ITI(R) implants were tightened into two metal models. SynOcta(R) abutments for cement-retained restorations and solid abutments were divided into two equal groups and were torque-tightened into the implants. Each implant received a cement-retained crown. Cyclic dynamic axial and lateral peak loads of 75+/-5 N were applied on the implants for a duty of 500,000 cycles at 0.5 Hz, and at an angle of 20degrees. Prior to the experiments and at each 100,000 cycles of loading, periotest values (PTVs) were measured. Removal torque values (RTVs) of the abutments were also measured with a custom-made torque device at the termination of the experiment. Results: All abutments and implants were clinically immobile and without any signs of mechanical failure. The final PTVs for both abutments were similar and the difference between groups was insignificant (P>0.05). The RTVs of solid abutments were significantly higher than synOcta(R) abutments (P<0.05). Conclusion: Predictable long-term clinical results can be achieved with solid abutments and synOcta(R) abutments for cement-retained restorations. Solid abutments possess higher removal torque resistance than synOcta(R) abutments when connected to synOcta(R) ITI(R) implants.