HAZZARDS OF OCCLUZAL FORCES ON THE IMPLANT SUPPORTED PROSTHODONTIC RESTAURATIONS-A FEM STUDY

Abstract

Since loading is increasingly believed to be a determining factor in the treatment outcome with oral implants, there is a need to expand the knowledge related to the biomechanics of oral implants. The aim of this study is to gain insight in the distribution and magnitude of occlusal forces on oral implants carrying fixed prostheses. This is done by in vivo quantification and qualification of these forces, which implies that not only the magnitude of the load but also its type (axial force). Occlusal forces on the supporting implants were quantified and qualified during controlled load application of 850 N on occlusal face of PMMA crown. The maximum displacement value is 0.16 mm, and the bone deformation in the implant entry area is 0.12-0.13 mm. It is also observed that the implant is slightly stressed on the outside and the threaded tip of the implant is more heavily stressed (about 300 MPa), with the following increasing threads reducing their contact stresses. The crown, made of PMMA, absorbs the external force over an area approximated by a circle. On this surface, the Von Mises stresses do not exceed 70 MPa, which are not at all dangerous as shear stresses.