araldite and Jaw--Edentulous

The aim of this study was to evaluate the distribution of generated stress around implants and adjacent bone tissue using different implant-retained overdenture designs through photoelastic analysis.. Over an edentulous human mandible, achieved from a human model, 2 or 4 microunit analog abutments were embedded (Master; Conexao Systems Prosthodontics, São Paulo, Brazil), settled in the interforaminal region. Three models of photoelastic resin (Araltec Chemicals Ltda, Hunstman, Guarulhos, São Paulo, Brazil), with 2 or 4 incorporated implants and microunit abutments, were obtained from molds using silicone for duplication. Inclusion, finishing, and polishing procedures were applied on the frameworks. This study was based on 3 different mechanisms of implant-retained mandibular overdentures: O'ring (GI), bar-clip (GII) (both with 2 implants), and their association (GIII) (with 4 implants). After the adaptation of each overdenture system on the photoelastic models, 100-N alternate occlusal loads were applied on back-side and front-side regions. The photoelastic analysis was made with the aid of a plain polariscope linked to a digital camera, Sony Cybershot α100, which allowed visualization of the fringes and registration of images on digital photographs.. The results demonstrated higher tension concentrated over the GIII, with a flat distribution of stress to the posterior ridge and overload on the posterior implants. GI showed the smaller stress level, and GII, intermediate level; there was distribution of stress to the posterior ridge in these 2 groups.. The use of bar attachment proved to be a better alternative, because it showed a moderate level of tension with a more uniform stress distribution and possessed higher retention than did the ball system.

Topics: Bite Force; Dental Abutments; Dental Implantation, Endosseous; Dental Prosthesis, Implant-Supported; Dental Stress Analysis; Denture Design; Denture Retention; Denture, Overlay; Epoxy Resins; Humans; Immediate Dental Implant Loading; Jaw, Edentulous; Mandible; Models, Dental; Phthalic Anhydrides