Fatigue and Static Performances of Narrow-Diameter Dental Implants

Abstract

Objective: The present study investigated the load-fatigue and static performances of one- and two-piece narrow-diameter implants. Materials and methods: Ten samples each of 3.1 mm, 3.5 mm one-piece, and 4.0 mm diameter dental implants were tested (n=30). A load-fatigue performance device was prepared based on ISO 14801. A sinusoidal piston (200 N loading) with a rate of 4 Hz was used to test each sample until it fractured or underwent 1x106 cycles. Then, a static test was performed on samples that survived the fatigue performance without any apparent failure. Compressive loading continued until the sample fractured, and the load/displacement curve was plotted. Statistical analysis was performed to compare the compressive loading values between 3.1 and 4.0 mm implants. Macro-failure analysis was performed to investigate the failure pattern and the associated implant design. Results: Regarding fatigue performance, 40% of 3.1 mm, 100% of 3.5 mm one-piece, and 20% of 4.0 mm implants failed. The mean compressive load value of the six samples of the 3.1 mm implants was 638 N (±60.2 N), and that of the eight samples of the 4.0 mm implants was 635 N (±65.2 N). The difference between these two values was not statistically significant. The compressive load/displacement curves of the 3.1 mm and 4.0 mm implants presented good elastic deformation changes until they reached the ultimate yield point. During cyclic and static loading tests, 50% of the 3.1 mm implants fractured in between micro- and macro-threads, whereas the 3.5 mm one-piece implants showed inconsistent fracture behavior. 80% of the 4.0 mm implants fractured between the fifth and sixth threads. Conclusions: The 3.5 mm one-piece implants showed atypical fatigue behavior. The 3.1 mm implants also showed unreliable fatigue performance. However, the mean compressive load values of the 3.1 mm implants were comparable to those of the 4.0 mm implants. With the limitations of the present study, narrow-diameter dental implants may be appropriate in zones that are not heavily loaded and not frequently in contact with other surfaces. Moreover, the use of properly designed quality implants is crucial for the long-term success of implant treatment.