Effect of artificial aging process and depth of curing on the amount of residual monomer in bulk fill composites polymerized with different light sources

Aim: The purpose of this study is to investigate the amount of monomer that is released from five different bulk-fill composite resins (Filtek Bulk Fill Flowable, Sonic Fill 2, Surefil SDR Flow, Venus Bulk Fill, Tetric N-Ceram Bulk Fill) and 1 conventional composite resin (Filtek Z250) exposed to artificial aging and polymerized at different thicknesses with different light sources and to compare composite materials with each other. Material and Method: Composite disks of both 2 mm and 4 mm thickness and with a diameter of 5 mm were prepared by using LED or QTH device. The resulting composite samples were transferred to glass vials containing 75% ethanol / water solution, and then the glass vials were divided into two groups. The glass vials in the control group were incubated at 37 ° C in three different time periods (0-1 days, 1-3 days and 3-7 days). The samples in the thermal cycle group were exposed to the thermal cycle (0-1 days: 1500; 1-3 days: 3000; 3-7 days: 6000) for the period corresponding to the three time periods specified in the control group. The monomers in the extractions samples taken at each time point were measured on an HPLC instrument. The obtained data were analyzed by repeated measures of variance analysis and tukey multiple comparison test (p <0.05). Results: Bis-GMA, TEGDMA, UDMA and Bis-EMA were released from Tetric N Ceram Bulk Fill, Sonic Fill 2, SDR and Venus Bulk Fill composites at maximum amount, respectively. On the first day the monomers were eluted at the highest level, IX while the monomer elution decreased over time. The application of the thermal cycle increased residual monomer elution and it was observed that the monomers reached cytotoxic levels in some time periods. There was no significant difference between light sources except the first 24 hours. The highest increase in the amount of Bis-GMA, TEGDMA, Bis-EMA monomer that was released with increasing thickness was observed in Sonic Fill 2 composites. The highest increase in the amount of UDMA monomer was detected in the Filtek Z250 composite. Conclusion: The majority of the monomer elution occurred during the first 24 hours and the amount of monomer that was released over time diminished. When the thickness of composite samples was increased from 2 mm to 4 mm, the proportion of the amount of monomers released varied according to the composite used. The amount of monomer obtained after thermal cycling operation was dependent on the thickness and structure of the composite material. Different light sources generally did not affect the amount of monomer released from the composites.