Effect of different boundary conditions on the reaction forces in a complete denture

Abstract

The purpose of this study was to compare the effect of mechanical bonding types on the forces induced between the implants and the cortical and cancellous bones of the lower mandible in complete denture prosthesis. Analysis was done using a three dimensional finite element method (FEM). A finite element model that contained the body of the mandible, mucosa, two implants with their O-rings, housing and prosthesis was constructed. Two types of models were considered in this study. In the first model, implants were evaluated without threads, and in the second model, the threads were considered. Two different unilateral loading cases were imposed on the prosthesis in this study, and each loading case was composed of three equal concentrated forces (20N) with different directions. The locations of the forces were 1st premolar, 1st molar and 2nd molar on the left side. The obtained results were the induced forces and stresses between the prosthesis and mucosa, and between the implants and the bones. The model was solved for eight different cases. The obtained results (average values) for the first and second implants and mucosa in the first loading condition were 2.33N, 13.15N and 48.63 N, and for the second loading condition were 13.04N, 31.24N and 36.18N respectively. The results for the simplest contact boundary condition were 2.45N, 12.99N and 49.01N, and the obtained results with threads were 13.19N, 13.10N and 36.99N for the first loading case. The results for different contact boundary conditions between the implants and bones and between the prosthesis and mucosa showed an increase in induced forces of approximately 7.74% and 1.71%, respectively in the two load cases. © 2009 Springer Berlin Heidelberg.