Influence of platform diameter in the reliability and failure mode of extra-short dental implants

Purpose To evaluate the influence of implant diameter in the reliability and failure mode of extra-short dental implants. Materials and methods Sixty-three extra-short implants (5 mm-length) were allocated into three groups according to platform diameter: Ø4.0-mm, Ø5.0-mm, and Ø6.0-mm (21 per group). Identical abutments were torqued to the implants and standardized crowns cemented. Three samples of each group were subjected to single-load to failure (SLF) to allow the design of the step-stress profiles, and the remaining 18 were subjected to step-stress accelerated life-testing (SSALT) in water. The use level probability Weibull curves, and the reliability (probability of survival) for a mission of 100,000 cycles at 100 MPa, 200 MPa, and 300 MPa were calculated. Failed samples were characterized in scanning electron microscopy for fractographic inspection. Results No significant difference was observed for reliability regarding implant diameter for all loading missions. At 100 MPa load, all groups showed reliability higher than 99%. A significant decreased reliability was observed for all groups when 200 and 300 MPa missions were simulated, regardless of implant diameter. At 300 MPa load, the reliability was 0%, 0%, and 5.24%, for Ø4.0 mm, Ø5.0 mm, and Ø6.0 mm, respectively. The mean beta (β) values were lower than 0.55 indicating that failures were most likely influenced by materials strength, rather than damage accumulation. The Ø6.0 mm implant showed significantly higher characteristic stress (η = 1,100.91 MPa) than Ø4.0 mm (1,030.25 MPa) and Ø5.0 mm implant (η = 1,012.97 MPa). Weibull modulus for Ø6.0-mm implant was m = 7.41, m = 14.65 for Ø4.0 mm, and m = 11.64 for Ø5.0 mm. The chief failure mode was abutment fracture in all groups. Conclusions The implant diameter did not influence the reliability and failure mode of 5 mm extra-short implants.