The evaluation of residual monomer released after polymerization of four different composite resins

Purpose: The aim of this study is to compare the amount of Bis-GMA, UDMA, and TEGDMA released from four different types of composite resins in three different time periods using the HPLC device. Materials and Methods: Four different composite resin materials with nanofiller content were used in the study. A total of 40 sample discs were prepared and polished to provide 10 pieces for each material. Each disc was 5mm in diameter and 2mm in depth. Samples were placed in amber glass bottles containing a solution of 75% ethanol / 25% water. On days 1, 15, and 30, 1mL samples were taken for measurement and transferred to 1.5mL glass vials. A total of 120 samples were prepared and analyzed using HPLC and the findings were analyzed statistically. Results: The retention times of the Bis-GMA, UDMA, and TEGDMA standard monomers were 5.3, 4.9 and 4.4 minutes, respectively. Bis-GMA and UDMA were released from all the materials used in the study. Only TEGDMA release was not observed from the Tetric EvoCeram material. There were significant differences in the total monomer release of all composite resins in terms of time. The maximum amount of release for each of the 3 monomers was on the 15th day. Conclusions: The biocompatibility of composite resins is proportional to the amount of monomer released. Residual monomers are cytotoxic on pulp or living tissues. There is a need for these results to be supported by further clinical studies.