In Vitro Comparison of Polymerization Techniques on the Strength and Hardness of Denture Base Resins

Purpose: Acrylic dentures fabricated using polymethyl methacrylate are subjected to either intraoral fatigue stress or extraoral impact stress, eventually forming microcracks and fractures. This limitation should be overcome by either modification in the acrylic resin material or in polymerization techniques. This study compares the impact strength and flexural strength of high-impact resin to conventional resin in short- and long-heat polymerization settings.

Methodology: The in vitro study design adopted a comparison of two groups of acrylic resin specimens, conventional and high-impact resin groups, with two subgroups, each undergoing short and long curing cycles. Specimens' flexural strength and impact strength were tested using the three-point bending test and Charpy's impact test (notched), respectively. The comparative analysis between the outcomes of curing cycles for each material and between the materials for each curing cycle was performed using the Mann-Whitney U test.

Results: The results of our study highlighted that the high-impact resin group with short cycles displayed statistically significant values on the flexural and impact strength. A comparison of flexural strength for the conventional resin group in different curing cycles showed that the short cycle had higher flexural strength than the long cycle, which was statistically significant. However, the difference in impact strength between curing cycles in the conventional resin group was not statistically significant.

Conclusion: High-impact denture base resin with short cycles will enhance denture properties with better flexural and impact strength.