Comparative Effect of different Polymerization Techniques on Residual Monomer and Hardness Properties of PMMA-based Denture Resins

• DOI: 10.5301/jabfm.5000199
• Publication Date: 2015-01-20T11:06:06Z
• Authors: Elif Aydogan Ayaz; Rukiye Durkan; Ayşegul Koroglu; Bora Bagis
• Keywords: Denture Bases; Bone Cements; Denture base resin; PMMA; Polymerization; Residual monomer; Heating; Dental Materials; Resins, Synthetic; 03 medical and health sciences; 0302 clinical medicine; Hardness; Materials Testing; Polymethyl Methacrylate; Autoclave polymerization; Pliability

Purpose The aim of this study was to compare the residual monomer and microhardness of poly(methyl methacrylate) (PMMA)–based denture resins processed by using autoclave and conventional water bath techniques. Methods To determine the amount of residual methyl methacrylate (MMA) monomer, disk-shaped specimens (n=5) were prepared from 3 different acrylic resins (Meliodent, Paladent and Qc-20). Control groups were polymerized in water bath for 30 minutes at 100°C. The study groups were prepared in an autoclave device for 60°C/30 min followed 130°C/10 min and the other group for 60°C/30 min followed by 130°C/20 min. According to standard calibration curves, ultraviolet spectrophotometry at 230 nm was used to determine the residual monomer. For the Vickers hardness measurements, disk-shaped specimens (n=5) were prepared for each test group. Hardness measurements were performed with a Vickers hardness tester under a 4.91-N press load for a 30 seconds, after immersion in distilled water at 37°C for 48 hours. The data were analyzed by ANOVA and Tukey HSD test (p<0.05). Results Autoclave polymerization produced a significant decrease in the amount of residual monomers for all resin groups (p<0.05). This procedure also showed a significant increase in hardness for all resin groups (p<0.05). For the 3 resin groups, no significant differences were found between autoclave polymerization for 10 minutes and for 20 minutes (p>0.05). Conclusions The autoclave polymerization technique exhibited significantly lower residual monomer content and greater hardness than conventional heat polymerization.