Loading conditions

The loading conditions assumed intercuspal clenching. On the assumption that occlusal force was generated by the contractile force of four bilateral masticatory muscles, the masseter, temporalis, mesial, and lateral pterygoid muscles, the loading points and the directions of the loads were determined based on the report by Korioth and Hannam and anatomical findings. The amount of the load was represented by the summation of the reaction forces at the occlusal surfaces of teeth in model-N. For example, the load condition that resulted in a total reaction force of 100 N in model-N was defined as Load100N.

Procedure for analysis

The load conditions used during occlusal adjustment were Load40N, as a light bite (Adj40N), Load200N, as a hard bite (Adj200N), and Load400N, as the maximum biting force (Adj400N). Occlusal adjustment was performed through trial and error with reference to the distribution of the occlusal force calculated by FE analysis. When the similarities of the distribution of the reaction force on the superstructures to that on the natural teeth in model-N were confirmed, the occlusal adjustment was completed. Thereafter, the FE analysis was performed again under the load conditions of Load40N, Load100N, Load200N, Load400N, and Load800N using the FEA software package MSC.Marc2010 (MSC Software). The distributions of the reaction forces on the occlusal surface and on the mandibular condyle, which were regarded as the occlusal force and the load on the TMJ, respectively, were evaluated.