Fatigue resistance and flexural behavior of acetal resin and chrome cobalt removable partial denture clasp: An in vitro study

Abstract

Statement of Problem: The denture clasp undergoes fatigue on the repeated deflection of the clasp during insertion and removal of the removable partial denture over the undercuts of the teeth. This study was conducted to know how acetal resin functions in this application. Aims: The purpose of the study was to evaluate fatigue resistance of acetal resin clasps subjected to repeated constant deflections and compare it with cobalt.chromium clasp. Materials and Methods: Acetal resin and Co.Cr clasp specimens were subdivided. (n = 10) specimens to perform deflection of 0.25 mm and 0.50 mm. Constant load for deflection of either 0.25 or 0.50. mm was applied to 2. mm from the point of the clasp at the appropriate loading frequency assuming that the clasps were inserted and removed from the abutment with undercut of either 0.25. mm or 0.50. mm. The fatigue test was carried out until 10 6 cycles or until permanent deformation detected. The data obtained were subjected to unpaired t -test. Results: It was observed that the deformation of chrome cobalt clasp specimen during the loading cycle of 106 under deflection of 0.5. mm was 0.1530 ± 0.0177 mm Chrome cobalt clasp under 0.25 mm deflection and an acetal resin specimen under 0.25 and 0.5 mm deflection did not show any significant deformation. Conclusions: The clasp with acetal resin may provide less retention than cobalt chromium.based alloys. For acetal resin clasp, no permanent deformation was detected after 106 loading cycles when deflected to 0.25. mm and 0.5. mm and has mean flexural strength of 72.436 MPa and modulus of elasticity of 2.245 GPa.