Comparison of Impact Strength and Fracture Morphology of Different Heat Cure Denture Acrylic Resins: An In vitro Study

BACKGROUND The fracture of acrylic resin denture is rather common occurrence and causes inconvenience to the patients. This study was carried out to evaluate and compare the impact strength and fracture morphology of four different heat cure acrylic materials. MATERIALS AND METHODS Acrylic resin specimens were prepared using preformed metal die of dimension 65 × 10 × 3 mm. The specimens were finished, polished and subjected to impact strength evaluation using impact testing machine. The loads at which the specimens fracture are recorded and subjected to statistical analysis. Fracture surface analysis was done. Macroscopic analysis was performed by visual inspection of the fractured surfaces using a stereoscopic microscope. About 5 mm sections of all the fragments were subjected to scanning electron microscopy for microscopic analysis to verify fracture morphology. RESULTS Mean values of the impact strength were compared by statistical methods. The impact strength data were subjected to variance homogeneity tests. Fracture surface analysis data was analyzed by statistical methods. The mean impact strength of Lucitone 199 was higher than Acrylyn-H, DPI Heat cure & Trevalon. CONCLUSION Within the limitations of this study, it was concluded that the impact strength of the acrylic resins is affected by the reinforcement of fibers. Increased intermediate fractures increased impact strength. Brittle fractures morphology showed fewer undercuts and clearer surface. Intermediate fractures morphology showed more undercuts than clear surfaces.