Effect of food stimulated liquids and thermocycling on the monomer elution from a nanofilled composite.

The present study was aimed to evaluate the effects of food simulating liquids and thermocycling on the elution of monomers from a nanofilled resin composite in different immersion times. Five Specimen discs were made from a nano-hybrid composite (Supreme 3M) for each group (Total = 180) and immersed in distilled water (control), citric acid, lactic acid, and 75% aqueous ethanol solution. The discs were removed after 24 h, 48 h, 72 h, 1 wk, 4 wk, and 12 wk. Three groups of samples underwent thermocycling for 1000, 2000 and 3000 cycles. The solutes were analyzed with HPLC for detection of eluted monomers. The results showed that the amount of released TEGDMA was significantly higher than that of Bis-GMA; however, there were not any significant differences between the amount of released Bis-GMA and UDMA. Moreover, the highest amount of monomers was released from samples immersed in ethanol solution; samples immersed in citric acid and lactic acid significantly released more monomers than those immersed in distilled water. Furthermore, the immersion time in aqueous ethanol solution had an increasing effect on the release of monomers. In addition, the higher amounts of monomers were release from samples immersed in ethanol and citric acid which underwent a higher number of thermal cycles. In conclusion, food and drink stimulated liquids used in this study increased the amount of some of the monomers released from composite resin. Thermal shocks and storage time are other factors that increased the release of monomers from the composite resin.