Elution of monomers from two conventional dental composite materials

Abstract

Objective The aim of this study was to determine the elution of monomers of two conventional resin composite materials after different polymerization and storage times. Methods Two resin composites (a hybrid and a flowable) were used. Four groups ( n = 10, diameter: 4.5 mm, thickness: 2 mm) of each material were fabricated, one for each polymerization time of: 0 s, 20 s, 40 s, and 80 s. The samples were stored in 1 ml of 75% ethanol at room temperature, and the storage medium was renewed after 24 h, 7 days, and 28 days. From the storage medium that was removed, samples were prepared and evaluated, with LC–MS/MS. Results Bisphenol A and UDMA were not detected in the samples. Regardless of the polymerization time, the material or the storage time, a higher amount of BisGMA was eluted compared to TEGDMA. The amount of monomer that was released from the polymerized samples of the hybrid resin composite (Tetric Ceram ®) was significantly higher ( p < 0.0001) compared to the flowable (Tetric Flow ®). No significant difference was found between samples polymerized for 20 s compared to 40 s concerning the elution of monomers. Only a polymerization time of 80 s resulted in a decreased release of monomers. The release of TEGDMA decreased after 28 days; however, the elution of BisGMA remained at high levels. Significance The release of monomers remains at a high level for a long time (7–28 days) after polymerization. The 40 s that are usually used for the polymerization of resin composites seems insufficient in order to prevent a high release of monomers.