According to the variables determined using Latin hypercube sampling, 500 FE models were constructed and analyzed under each of the loads following the construction of response surfaces with the MES as a response value. D and L were minimized by optimized calculation with the MES limited to the physiological limit with reference to the mechanostat theory.Results: The MES was significantly influenced by D more than L, and could be restricted to the physiological limit unless both C and T were small. Finite Element ModelWe created three-dimensional finite element models (Fig. 1) 2). The superstructure of the implant prosthesis was simplified and consisted of gold alloy. All components, the bone, the superstructure, the abutment, and the implant body, were assumed to be fixed to each other.The models consisted of approximately 84,000 nodes and 80,000 hexahedron elements on average. All elements were homogenous and isotropic. The properties of the materials (Table 1) were based on previous studies. The nodes on the mesial and distal sections of the mandible were restrained in all directions. Loading Conditions

BackgroundThe purpose of this study was to investigate the influence of occlusal forces (the contractile force of masticatory muscles) exerted during occlusal adjustment on the distribution of the forces among teeth, implants, and temporomandibular joints (TMJs) in intercuspal clenching in cases with bilateral missing molars and premolars by using finite element analysis.MethodsA three-dimensional finite element model of the mandible with eight implants in the premolar and molar regions was constructed. Linearly elastic material properties were defined for all elements except the periodontal ligament, which was defined as nonlinearly elastic. The TMJs and antagonists were simplified and replaced with nonlinear springs. Antagonists were assumed to be natural teeth or implants and had two- or three-stage displaceability. We constructed finite element (FE) models in which occlusal adjustment with three kinds of occlusal force (40 N as a light bite, 200 N as a hard bite, and 400 N as a maximum biting force) was performed. The clearance by occlusal adjustment was decided beforehand with a trial-and-error method so that the occlusal forces were distributed similarly to the distribution of the natural dentition. Each model was evaluated under loads of 40, 100, 200, 400, and 800 N to determine the distribution of occlusal forces on the teeth and implants.ResultsThe occlusal forces were concentrated on the most posterior implants while the load was larger, and the percentage of bearing force at the TMJ was small, and vice versa.ConclusionsMaximum biting force was better for occlusal adjustment to prevent overloading of the most posterior implant.

No abstract