Comparison of the periimplant bone stress distribution on three fixed partial supported prosthesis designs under different loading. A 3D finite element analysis

Abstract

Background: Despite high success and survival rates of implant supported prosthesis therapy, biomechanical complications such as periimplant bone resorption continue to exist due to occlusal overloading. Purpose: To analyze and compare the influence of bone density, direction and distribution of the occlusal load and the design of three-unit implant supported prostheses. Materials and methods: Three dimensional finite element analysis study was developed to evaluate the influence on the periimplant bone stress distribution of three different designs of a 3-unit bridge supported by two implants (intermediate pontic, tilted implant, cantilever pontic), two different bone qualities (D3 and D4), and different loading directions (axial and non axial) and distributions (uniform and non uniform). Results: Bridge configuration with intermediate pontic and parallel implants presents the lowest periimplant stress, whereas the highest stress was found on the tilted implant bridge. Bone D3 is biomechanically more favourable than D4. Non axial and uniform loading conditions produce more periimplant stress. Conclusions: Distal cantilever and 45˚ convergent distal tilted implant are the second and third treatment options on a posterior three unit rehabilitation. Lightening occlusal contacts on the pontic and avoiding non axial loading, reduce periimplant bone stress. Bone D4 increases periimplant bone strain.