Effect of dental implant diameter on fatigue performance. Part I: mechanical behavior.

AIM The purpose of this study was to evaluate the effect of the implants' diameter on the mechanical function and load-fatigue performance of dental implants. MATERIALS AND METHODS Three groups of implants with different diameters (3.3 mm, 3.75 mm and 5 mm), were tested under static and cyclic compressive loading. A total number of 15 implants for the static test and 112 implants for the cyclic-fatigue test. In the cyclic test, the machine ceased operating when the structure collapsed or when it reached 5 × 10(6) cycles without apparent failure. The load versus the number of cycles was plotted as curves for biomechanical analysis (S-N curve) for each implant diameter. RESULTS The S-N curve plotted for the 5 mm implants showed classic fatigue behavior with a finite life region starting from 620N. The same was observed for the 3.75 mm diameter implants, with a finite life region starting below 620N. By contrast, the 3.3 mm diameter implants failed to show predictable fatigue behavior and a fatigue limit could not be defined. CONCLUSIONS The results of this study emphasize the importance of implant diameter on fatigue behavior. Narrow implants failed to show typical fatigue behavior which might be attributed to the implant design.