Numerical analysis of geometric characteristics of mandible fixation plates made of hydroxyapatite structures

Abstract

Bone defect reparation can be successfully performed with biomaterials based on synthetic hydroxyapatite (HA). In addition to collagen, hydroxyapatite is the basic structure of bone tissue and it is expected to have excellent biocompatibility. This study presents analysis of HA properties, its biocompatibility, and its enhancement due to the reinforcement by biocompatible polymers. This implies the use of bioresorbable poly-L-lactide (PLLA) and bioresorbable HA to produce a unique high porosity composite HA/PLLA with mechanical properties very similar to bones. Using the finite element method, the influence of the mandible fixation plate geometry on the stress distribution is analysed. There are several existing fixation plate models but also a few new-design plates. The mandible model is made with several assumptions. The total effect of occlusal forces is approximated by a 150 N load in mandible muscle. Analysis shows that the best characteristics appear in large surface fixation plates, but the minimum surface plate design with two rows of screws is selected due to the connecting problem in the bone-implant system (naturally uneven).