The evaluation of residual monomer release after polymerization of four different composite resin

Aim: The aim of this study is to measure and evaluate the amount of released residual monomer (Bis-GMA UDMA ve TEGDMA) after polymerization from four different nanofiller composite material during different time slots by High Performance Liquid Chromatography (HPLC) technique . Material and Method: In our study, four different composite resin materials with nano filler content were used (Grandio, Filtek™ Ultimate Universal, Clearfıl Majesty Posterior ve Tetric EvoCeram). A total of 40 sample discs were prepared and polished such a way that 10 pieces of each material would be used. Each disc has a diameter of 5mm and a height of 2mm. Samples were placed in amber glass bottles containing 75% ethanol / 25% water solution. On the 1st, 15th and 30th days, 1mL samples were taken for measurement and transferred to a 1.5mL glass vials. Thus total of 120 samples were prepared and used during the experiment. 6 different solutions of the monomers were prepared and the HPLC instrument was calibrated and chromatographic conditions were established. Retention times of pure monomers were determined. The samples were analyzed by HPLC and chromatograms were obtained. Shapiro-Wilk test was used for normal distribution. The One Way Anova test was used to compare the amount of residual monomer release between different brands. Tukey HSD test was used to determine which brand and which monomer made the difference. Bonferroni test was used for dual comparisons in repeated experiements. During the evaluation of these test, p <0.05 was considered statistically significant. Results: The retention times of the Bis-GMA, UDMA and TEGDMA standard monomers obtained 5.3, 4.9 and 4.4 minutes, respectively. Bis-GMA and UDMA were released from all of the materials used in our study. However TEGDMA release was not observed only from the Tetric EvoCeram material. There are significant differences in the total monomer release of all composite resins in terms of time.It was found that the maximum amount of release for each of the 3 monomers was on the 15th day. Conclusion: In all time periods, it was determined that residual monomer release occurred from the materials. Residual monomers can damage the pulp through the dentine tubules. It can cause local or systemic toxicity by absorbing or swallowing soft tissues. Protective measures sould be applied such as methods to provide maximum polymerization, the use of pulp protective materials and the use of composite resins with increased filler content . Keywords: nanofiller composite resin, residual monomer, high performance liquid chromatography, biocompatibility