Bending Strengths of Metal Framework Structures for Implant-stabilized Overdentures

Abstract

Purpose : This study evaluated the bending strengths of five types of framework structures for implant-stabilized overdentures.Materials and Methods : Five types of framework structures for implant-stabilized removable prostheses were cast using a Co-Cr alloy : conventional housing (Type A), housing with short skeleton (Type B), long skeleton only (Type C), housing with long skeleton (Type D), and Type D plus a metal backing connected by columns (Type E ; hereinafter referred to as the “double structure”). All castings were embedded in a heat-cured denture base resin. As controls, the same size resin blocks without frameworks were prepared. A bending test was used to test each specimen as it acted as a fulcrum on the implant. Breaking load, maximum stiffness, and strain were measured.Results : The breaking load and maximum stiffness of the double structure were significantly greater (p<0.05), i.e., 1.5-4.5 times and 2-6 times greater, respectively, than for the conventional frameworks.Conclusion : When the double structure framework was used for implant-stabilized prostheses, the bending strengths were greater than for the conventional housing design.