Comparative Evaluation of Surface Hardness and Water Sorption of Heat-Cure and Microwave-Cure Denture Base Resins after Simulated Oral Aging
Main Article Content
Abstract
Objectives
This study aimed to comparatively evaluate the surface hardness and water sorption of conventional heat-cure and microwave-cure polymethyl methacrylate (PMMA) denture base resins before and after simulated oral aging via thermocycling.
Materials and Methods
A total of 40 disk-shaped specimens (20 mm in diameter and 3 mm in thickness) were fabricated and divided into two equal groups (n=20 each): Group A (Conventional Heat-Cure PMMA) and Group B (Microwave-Cure PMMA). Baseline surface microhardness was evaluated using a Vickers hardness tester under a 50-gf load for 15 seconds. The specimens were then subjected to simulated oral aging through thermocycling for 5,000 cycles between 5 ∘ C and 55 ∘ C. Water sorption was calculated by measuring mass changes using a digital analytical balance before and after water storage according to ISO 20795-1 specifications. Post-aging surface hardness was recorded. Data were statistically analysed using independent and paired t-tests (α=0.05).
Results
At baseline, Group B exhibited significantly higher surface hardness (21.25±0.85 VHN) compared to Group A (19.82±0.94 VHN, p<0.05). Following simulated oral aging, both groups exhibited a statistically significant decrease in surface hardness (p<0.05); however, Group B maintained a significantly higher post-aging hardness (18.12±0.76 VHN) than Group A (16.45±0.88 VHN). Regarding water sorption, Group B showed significantly lower mean values (15.84±1.12 μg/mm 3) compared to Group A (18.96±1.34 μg/mm 3, p<0.01).
Conclusion
Microwave-cured denture base resins demonstrate superior surface microhardness and enhanced resistance to water sorption compared to conventional heat-cured resins, both at baseline and after simulated oral aging. Clinically, microwave processing offers a structurally stable alternative with improved durability in the oral environment.
Article Details
References
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