Load fatigue performance of conical implant-abutment connection: effect of torque level and interface junction.

AIM: The objective was to evaluate the mechanical behavior and the effects of interface abutment/implant on implants with Morse taper connections after the application of cyclic loads.

METHODS: A total of 30 implants with Morse taper diameters of 4 mm and lengths of 11 mm with 30 straight solid pillars were divided into two groups. The control group (Gcon) (N.=15) was evaluated after receiving only 25 N of torque. The experimental group (Gexp) (N.=15) was subjected to torque and 360,000 cycles of mechanical fatigue at a load of 100 N and a frequency of 4 Hz. After testing, ten abutments from each group were removed from the implants to record removal torque values. The remaining five abutments/implants from each group were embedded in metallographic resin after testing and were cut along their perpendicular center axes of contact for analysis of the internal walls between the abutments and the implants.

RESULTS: The removal torque increased by 19.7% (N.=29.9) for the Gexp group and decreased by 11.8% (N.=22.3) for the Gcon group, indicating a statistically significant difference (P=6.82-10) between the groups. The interface of the abutment/implant assembly was morphologically different between the Gcon group and the Gexp group. After mechanical cycling, spaces were no longer visible at the interface.

CONCLUSION: After cyclic loading, the implant removal torque increased. The metallographic sections revealed that there was more contact between the inner walls of the abutment/implant sets after cyclic loading. This information is especially important in cases of single implants, because the system (abutment/implant) will have less chance of loosening.