Effect of resin application time on bond strength of polymer substrate repaired with particulate filler composite

Four different polymeric substrates were treated with unfilled intermediate resin (IMR) for various lengths of time (15 s, 3 min, 1 h, 24 h, and 2 weeks) to find out the effect of IMR treating time on shear bond strength between the substrate and a particulate filler composite. The IMR used in the study was a diacrylate monomer resin and the particulate filler composite was added on it. Two of the tested substrates were fiber-reinforced composites (FRCs). Two other substrates were cross-linked bisphenol-A-glycidyl dimethacrylate/triethyleneglycol dimethacrylate (BisGMA/TEGDMA) substrate and linear polymethylmethacrylate substrate. The bond strength of the particulate filler composite to the BisGMA/TEGDMA substrate was significantly higher compared to the other substrates (p<0.001). A correlation between increasing shear bond strength and longer treating time were found with the BisGMA/TEGDMA substrates (r=0.594, p<0.001) whereas no correlation was found with the other substrates. Prolonging of IMR treating time enhanced the BisGMA/TEGDMA substrate bond strength to the particulate filler composite but it had no clear effect on the bond strength of other substrates.