The Influence of Temporo-Mandibular Joint Support Conditions and Osseintegration on Mastication Load Transfer in a Mandibular Prosthesis

In the design of mandibular implants, the application of previous research findings, which highlight the significance of asymmetric occlusal load transfer schemes, is often lacking. The generated identical oblique occlusal force for maximum muscle efficiency may not be the sole criterion for assessing the load-bearing capacity of a mandibular prosthesis. The hypothesis of this study was that the load-bearing capacity of extensive mandibular prostheses is significantly underestimated when assuming mandibular support at the temporomandibular joint on the occlusal side compared to the assumption of perfect osseointegration between the implant and bone. Finite Element Method (FEM) simulation studies were conducted to analyze occlusal load transfer, considering two joint support conditions: support in both temporo-mandibular joints and support in only one joint, opposite the bite side. Additionally, two variants of the implant-bone connection were examined: an optimistic scenario assuming complete osseointegration and a pessimistic scenario assuming no osseointegration, with fixation achieved solely through bone fixation plates. The findings indicated a significant underestimation of the loads transferred by the implant and bone tissue when symmetrical joint support and osseointegration were assumed. Although there is currently no conclusive evidence supporting the complete exclusion of the joint, the computational results demonstrated that, in the absence of precise data regarding the percentage contribution of the joint on the occlusal side, it is preferable to employ more stringent criteria for assessing the load-bearing capacity of mandibular prostheses. This assessment should include the exclusion of joint support on the occlusal side to ensure a more conservative and reliable evaluation of the prosthesis’s mechanical performance.