Design Optimization of Denture Prostheses by Fatigue Evaluation System

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This project was conducted to develop a design optimization system of dental prostheses including removable dentures and implant prostheses based on the evaluation of fatigue resistance. The prosthodontic design was optimized to minimize the fatigue fracture and failures in the long term clinical use of the dentures.Three categories of investigations were conducted ; 1) Fractographic analysis of clinically failed removable dentures and implant prostheses, 2) Mechanical analysis by means of finite element models of clinically failed removable dentures and implant prostheses, and 3) Fatigue tests of the removable denture and implant materials, and subsequent investigation of the correlation of the results with clinically failed dentures. In the study 2, stress distributions created in the structural components of the removable dentures and implant prostheses such as rest, major and minor connectors, clasps, interfacial region between the resin and the metal, implant neck, and implant superstructures, were analyzed by means of standardized finite element models. It was indicated in this part of the project that the clinical failure probability was closely related to the maximum tensile stress shown in the models, while the geometry and dimensions of the denture components did not necessarily cause the failure initiation. The result was confirmed by matching verification with the results shown in the study 1. In the study 3, the cause and effect relations of the tensile peak stress in the models with the failure probability of the clinically used dentures were generalized. The results of this comprehensive analysis suggest possibility of establish the design optimization system of dental prostheses based on the fatigue resistance of the denture structures. Detailed results of the analyses have been published as described in the next page. The prosthodontic design should be now systematically executed in line with the design optimization theory indicated in this project.