Biomechanical Evaluation of Implant Size and Osseointegration Using Three-dimensional Finite Element Analysis

BACKGROUND: Finite element analysis (FEA) is a technique for obtaining a solution to a complex mechanical problem by dividing the problem domain into a collection of much smaller and simpler domains (elements) in which the field variables can be interpolated with the use of shape functions. Load transfer from implants to surrounding bone depends on the type of loading, the bone-implant interface, the length and diameter of the implants, the shape and characteristics of the implant surface, the prosthesis type and the quantity and quality of the surrounding bone. FEA allows researchers to predict stress distribution in the contact area of the implants with the cortical bone and around the apex of the implants in trabecular bone. AIMS: This study aimed to compare the stress and strain on a single implant and its surrounding bone for various implant lengths and diameters, both before and after osseointegration. MATERIALS AND METHODS: An initial model of a single implant substituting a second premolar was developed with reference to a posterior cross-sectional area of both cortical and cancellous bone on a personal computer using ANSYS software. The length and diameter of the implant were assumed to be L = 11.5 mm and D = 4 mm. The loading condition was performed by the application of the static vertical force of 118.2 N to the node of the implant. RESULTS: Increased implant length results in stress reduction on the implant in both immediate and delayed implant loading. In the present study, the Von Miss Stress are reduced. Furthermore, increased implant diameter results in stress reduction on the implant in both immediate and delayed implant loading. CONCLUSION: The present study indicates that implant length prior to and after osseointegration is not the sole factor affecting stress/strain distribution pattern. There are other influencing factors like type of loading, the bone-implant interface, the length and diameter of the implants, the shape and characteristics of the implant surface, the prosthesis type and the quantity and quality of the surrounding bone.