Investigation of different bleaching conditions on the amount of elutable substances from nano-hybrid composites

AbstractObjectives lyse the influence of irradiation time, aging before bleaching, and bleaching technique (home bleaching vs. in-office bleaching) on the amount of elutable substances from modern nano-hybrid resin-based composites (RBCs). s ens (n = 5) of three nano-hybrid RBCs (Venus® Diamond, Tetric EvoCeram® and Filtek™ Supreme XTE) were irradiated for 5, 10, 20 and 40 s. The degree of conversion (DC) was measured in real-time with Fourier transform infrared spectroscopy (FTIR). Specimens were bleached either directly after irradiation or after aging (1.5 or 6 month in distilled water at 37 °C) with Opalescence® PF15% for 6 h (simulation of home bleaching) or PF35% for 0.5 h (simulation of in-office bleaching) and incubated in ethanol/water (3:1) at 37 °C for 7 d. The eluates were analyzed by gas chromatography/mass spectrometry. Unbleached specimens at the above mentioned irradiation times were used as controls. s ing increases the amount of elutable substances. This amount is generally stronger influenced by aging than by polymerization time or concentration of the gel. 2-Hydroxyethyl methacrylate was found in amounts up to 334.14 (106.91) μmol/l (Tetric EvoCeram®, irradiation time 5 s; bleaching with 15% CP) as a destruction product. Diethoyxdimethylsilane was found in all eluates from bleached specimens, but not in the control groups. This substance may be formed by oxidation of 3-methacryloxy-propyltrimethoxysilane, indicating that the bond between inorganic filler and organic matrix might be weakened after bleaching. icance ing gels might alter the physical properties of resin-based composites, especially at low irradiation times and fresh placed restorations.