Fatigue Strength of the Metal Framework Structures for Removable Partial Dentures

The structural design of the metal alloy framework for removable partial dentures is critical. A double structure framework was the representative of these designs, which enables the mechanical strength and durability to improve and the abutment teeth and alveolar ridge to protect. In this study, several structural designs (double structure, T-shapes, trussed structure, rectangular column, nonuniform section) including resin block as control were subjected to a load-controlled fatigue test. The benefits on fatigue strength of five types of structures were evaluated to record the number of cycles at catastrophic failure, to measure continuously displacement and strain under loads repeatedly, and to observe the fracture patterns. The results were as follows: 1. Maximum stiffness of double structure and T-shapes was approximately 20 times that of rectangular column and nonuniform section by theoretical calculations. 2. Fatigue strength of double structure was the highest, followed by that of trussed structure and T-shapes. 3. Double structure was found to be the significantly lowest of both displacement and strain. 4. Packed resin fracture was observed in all specimens except double structure. 5. The interface of fractured specimen frameworks were revealed inherently with fatigue.