Load Transfer of abutment tooth with post and core for Various mandibular distal extension cases with diminished periodontal support

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The purpose of this study was to investigate the stress redistribution in the pulp and non-pulp abutments in bilateral and unilateral distal extension cases with reduced periodontal support of three retainers device configurations based on the RPI system, Konus Krone system, and Bracing arm system using Quasi-three-dimensional Photoelastic method, High-speed Photoelastic Experimental Method and Finite Element Method.Three composite photoelastic models were made of a mandible unilaterally and bilateral edentulous distal to the second premolars. Individual simulant materials were used for tooth structure, periodontal ligament, and alveolar bone of periodontally compromised. Three retainers were cast for the teeth. Unilateral and bilateral partial dentures with three retainer designs, RPI system, Konus Krone system and Bracing arm system were made for the three models. Simulated vertical and lateral occlusal loads were applied to the dentures, and the stresses which developed in the suppo … More rting structures were monitored photoelastically.As a results, it's became clear the following. 1)The stress redistribution patterns in the abutments and surrounding tissues differed between the three systems. 2)The RPI system configurations showed the most uniform redistributions across loads directed in all five directions, while Konus Crone systems showed favorable stress redistribution for vertically, posteriorly, and buccally directed loads and Bracing arms configurations showed favorable stress redistribution for anteriorly and lingually directed loads. 3)the highest stress concentrations were seen in the abutment with the least periodontal support : the 35% horizontal defect. Increasing the number of splinted teeth did not provide a proportional decrease in maximum stress levels. 4)higher stress concentrations were seen in the abutment of non-pulp with post metal core. 5)The differents stress developed by lateral condensation root canal filling using various sizes spreddar. 6)it's became same results both Quasi-three-dimensional Photoelastic Method and Finite Element Method. Less