Effect of Implant Diameter on Fatigue Strength

Purpose: To investigate the effect of implant diameter on fatigue strength using static and cyclic load test. Materials and Methods: Four different implant systems-SuperLine (Φ4.0), NRLine (Φ3.1), SlimLine (Φ2.8, Φ2.3), and (Dentium)-were grouped by implant diameter. A static load test was conducted with 5 specimens for each group using a universal testing machine to measure the ultimate failure load (UFL). With 80% of the UFL in the weakest group, the starting load for a cyclic load test was determined and the test was performed with 8 specimens for each group. All tests were conducted according to ISO14801 (2007) until implant failure occurred. After dynamically loaded, each specimen was sectioned and stereo-microscopically examined. The failure modes of each implant system were classified. Static and cyclic load test data were respectively analyzed after the test of normality, with the level of significance at P = 0.05. Results: In the static load test, the higher maximum load of the standard-diameter implant was significant compared with the recorded narrow or mini-implants (P < 0.05). The yield strengths of the Φ2.8 and Φ3.1 implants were significantly greater than that of the Φ2.3 implant (P < 0.05). In a cyclic load test, the mean number of cycles until implant failure occurred was recorded for each specimen. The value for the Φ4.0 implant was significantly greater (P < 0.001). Conclusion: Implant diameter has an effect on the ability to withstand both static and cyclic loads within Dentium implant systems, The UFLs and fatigue cycles decreased as the implants diameter became smaller.