Biomechanical Aspects of Bone-Level Diameter Shifting at Implant-Abutment Interface

Purpose: To evaluate the effect of diameter shifting at implant-abutment interface on load distribution at periimplant bone and within implant-abutment complex. Materials: Eight different implant-abutment connections were designed and simulated numerically. Implant-abutment microgroup at bone level was hypothetically set-off inward toward the central avis of implant to create "diameter shifting" or "platform switching" Concept. The conceptual design was further characterized with horizontal set-off distance, emergence angle, and restorative height. A control model of Conventional implant-abutment connection with restorative relation was also involved,for comparison of developed stresses in periimplant bone and within unplant-abutment complex. A 14 mm x 16 mm acryclic cylinder with vertically placed implant-abutment complex was Considered for all designs. Principal and Von Mises stresses under vertical and oblique static loading conditions were evaluated numerically and presented descriptively. Results: Stress distribution at periimplant bone was almost identical with similar magnitudes for all designs. Increase in the horizontal set-off distance generated higher stress magnitudes and increased stress intensity within the implant-abutment complex. Discussion: Platform. switching based designs of implant-abutment connections need more mechanical studies to identify the optimum design for long-term mechanical stability. Conclusions: Relocation of microgap and redefinition implant-abutment connection at bone level does not influence the stress characterization at periimplant marginal bone but may noticeably affect the mechanical properties of the implant-abutment connection. (Implant Dent 2009;18:239-248)