Purpose: To evaluate residual monomer release from resilient denture lining materials polymerized by different methods.
Methods: Two materials were assessed: Ever-Soft polymerized by hot water bath or microwave energy, and Light Liner polymerized by chemical reaction and visible light (dual polymerization). Residual monomer release was measured in 12 specimens (40x10x0.3mm) made of each material and polymerization method. The specimens were stored in distilled water for 168 hours at 37ºC, and analyzed daily by ultraviolet spectrometry (Light Liner: 204nm, Ever-Soft: 206nm). Data were analyzed by one-way ANOVA and Bonferroni test (α=0.05). The residual monomer released as a function of time was determined by polynomial regression analysis.
Results: Residual monomer amount released at 168 hours from specimens polymerized by hot water bath (0.27±0.01μg/cm2) was significantly greater (P < 0.05) than from those processed by microwave energy (0.25±0.02μg/cm2). Ever-Soft showed decrease in monomer release over time, tending to stabilize at 96 hours. Light Liner continued to release monomer over time.
Conclusion: Ever-Soft may be polymerized by microwave energy. Residual monomer release values were low, and the monomer levels decreased over time.
Key words: Laboratory research; resilient lining material; residual monomer