Comparative effect of different polymerization techniques on residual monomer and hardness properties of PMMA-based denture resins

J Appl Biomater Funct Mater. 2014 Dec 30;12(3):228-33. doi: 10.5301/jabfm.5000199.


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 37ºC 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.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Bone Cements / chemistry*
  • Dental Materials / chemical synthesis*
  • Denture Bases*
  • Hardness
  • Heating / methods
  • Materials Testing
  • Pliability
  • Polymerization*
  • Polymethyl Methacrylate / chemistry*
  • Resins, Synthetic / chemical synthesis*


  • Bone Cements
  • Dental Materials
  • Resins, Synthetic
  • Polymethyl Methacrylate