Numerical study of the influence of material parameters on the mechanical behaviour of a rehabilitated edentulous mandible

Abstract

Objectives: The study dealt with full dental prosthetic reconstruction on four implants. The aim was to analyse the influence of material parameters on the mechanical behaviour of the restored mandible compared to the natural mandible.

Methods: A finite element model of an edentulous mandible with prosthetic rehabilitation was established. Four materials were investigated for the framework of the prosthesis (zirconia, titanium, gold and nickel-titanium (NiTi)), as well as three cortical bone thicknesses. Various muscles were employed to simulate the main stages of mastication. Three distinct phases of mastication were modelled: maximum intercuspation, incisal clench and unilateral molar clench.

Results: The zirconia framework demonstrated the highest stresses and NiTi the weakest. The highest stresses in the framework were obtained during maximum intercuspation. The highest stresses at the bone-implant interface were recorded on the working axial implant during unilateral molar clench and on tilted implants during maximum intercuspation. The influence of the framework's material stiffness on the stresses at the bone-implant interface was insignificant for axial implants (except the right implant during unilateral molar clench) and slightly more significant for tilted implants. Mandibular flexion decreased with an increase of the cortical bone thickness and the stiffness of the prosthetic framework's material.

Conclusions: Among all materials, NiTi allowed a better preservation of the mandibular flexure, during all the mastication stages. Compared to stiffer materials, NiTi also permitted physiological mechanical conditions at the bone/implant interface, in almost all mastication stages.

Keywords: Finite element analysis; Implant; Mandible kinematics; Prosthodontic.