Stress Analysis of an Endosseus Dental Implant by BEM and FEM

Abstract

In this work the Boundary Element Method (BEM) and the Finite Element Method (FEM) have been used for an elastic-static analysis of both a Branemark dental implant and a generic conic threaded implant, modelled either in the complete mandible or in a mandibular segment, under axial and lateral loading conditions. Two different hypotheses are considered with reference to degree of osteo-integration between the implant and the mandibular bone: perfect and partial osteointegration. The BEM analysis takes advantage of the submodelling technique, applied on the region surrounding the implant. Such region is extracted from the overall mandible and the boundary conditions for such submodel are obtained from the stress analysis realised on the complete mandible. The obtained results provide the localisation of the most stressed areas at the bone-implant interface and at the mandibular canal (containing the alveolar nerve) which represent the most critical areas during mastication. This methodology, enriched with the tools necessary for the numerical mandible reconstruction, is useful to realise sensitivity analysis of the stress field against a variation of the localisation, inclination and typology of the considered implant, in order to assess the optimal implant conditions for each patient under treatment. Due to the high flexibility in the pre- and post-processing phase and accuracy in reproducing superficial stress gradients, BEM is more efficient than FEM in facing this kind of problem, especially when a linear elastic constitutive material law is adopted.