Leaching and mechanical properties characterization of dental composites.

The objective of this study was to determine the leaching of Ba, Si, and Sr from four dental composites: Restolux (RX), Micronew (M), Renew (RW), and Choice (C) and to correlate the effects of such leaching with flexure strength and modulus of elasticity. The specimens were 3 x 3 x 25-mm bars, polished with 120- and 240-grit SiC paper, and were aged for 4, 6, and 8 months in artificial saliva, distilled water, and a 50/50 mixture of ethanol and distilled water. Inductively coupled plasma with mass spectroscopy (ICP/MS) was used to determine the ion concentrations after aging. The greatest release of Ba and Sr occurred after aging in 50/50 volume fraction mixture of ethanol/water and for Si in artificial saliva. The 50/50 solution caused a breakdown of the resin and glass matrix, resulting in an increase of Ba and Sr, whereas aging in artificial saliva resulted in an ion charge balance, which allowed an elevated and continuous release of Si. The flexure strength and the elastic modulus showed a gradual decrease over time, with the greatest decreases occurring following aging in the 50/50 water/ethanol solution, but little correlation with the leaching of the filler ions.