Photoelastic Stress Analysis for Cobalt Chromium and Nylon Denture ‎Base on Mandibular Kennedy Class I Implant Supported Removable ‎Partial Overdenture

Objective: The purpose of this study was to evaluate stresses induced on implant supported cobalt chromium and nylon overdenture bases in free end saddles cases using photoelastic stress analysis. Materials and Methods: Ready-made mandibular stone cast fabricated according to Kennedy Class I to replace 2 nd premolar, 1 st and 2 nd molars. Implant analogue was inserted at site of first molar by using milling machine. Closed tray silicone impression was taken to the stone cast after transfer coping insertion. The transfer coping was inserted on its place in the impression. The implant was placed on its position in the impression. The impression was poured with epoxy resin material. Metallic and nylon denture bases were constructed with same design. Forces of 20, 40, 60, 80, 100 (Newton) were applied to detect photoelastic stresses. Results: With application of loads 80 and 100 N, the nylon framework recorded higher stress values than the vitalium framework at apical, middle and cervical area bilaterally. Conclusion: Cobalt chromium denture base showed better stress distribution compared to nylon denture base.