Joint Strengths of Metal Framework Structures for Removable Partial Dentures

抄録

Purpose : This study investigated the joint strengths of two frameworks for removable partial dentures (RPD) embedded in a denture base resin.
Materials and Methods : Six types of framework structures were cast conventionally from a Co-Cr alloy. To connect two castings, six types of joints were designed : Type A (butt joint), Type B (soldered butt joint), Type C (soldered lap joint), Type D (10 mm overlapped T-shape), Type E (20 mm overlapped T-shape), and Type F (Type D with two pins). Two castings were embedded in denture base resin and finished to a size of 10.0×10.0×65.0 mm. As a control, the same size resin block without a framework was prepared. Joint strengths were determined using a three-point bending test. To evaluate the strength change after rejoining, the broken specimens were reconnected using the same resin and tested as in the first test.
Results : Both the breaking load and maximum stiffness of Types D, E, and F were significantly (p<0.01) greater than those of Types A, B, and C. Using the same resin for repair, the joint strengths of every type were not significantly (p>0.05) different between the before- and after-repair state.
Conclusion : Because of the design of the three-dimensional RPD frameworks, greater joint strengths were obtained than for the conventional soldered framework design.