Effect of Different Photoiniciers of Experimental Adhesive Systems on Adhesive Interface Union Resistance

Aim: The objective of this study was to investigate the performance of experimental resinous adhesives containing different combinations of photoinitiators systems through the bending test. Material and Methods: Resinous adhesive formulations were prepared with monomer mixtures consisting of 50% by mass of bisphenol dimethacrylate glycidyl (BisGMA) and 50% by mass of triethyleneglycol dimethacrylate (TEGDMA). The photoinitiators were used, camphorquinone (CQ) and bis-alkyl phosphinic oxide (BAPO). The co-initiators were diphenyliodonium hexafluorophosphate (DFI) and the amine (dimethylamino methylmethacrylate - DMAEMA) in the 1:1 proportion by mass. The photopolymerizable initiator systems were dissolved in the organic matrix at 0.5% by mass concentrations, creating eight groups (G1- CQ, G2- CQ/amine, G3- CQ/DFI, G4- CQ/amine/DFI, G5- BAPO, G6- BAPO/amine, G7- BAPO/DFI, G8- BAPO/amine/DFI). Samples with 7.0 mm in length, 2.0 mm wide and 1.0 mm height were prepared (n=12). The curing light used was VALO – Ultradent and the curing time was 20 s. The samples were subjected to evaluation of bending test at three points at a speed of 1 mm/min to evaluate the flexural resistance (FR). Results: The results were submitted to analysis of variance with one criterion (p < 0,001) and multiple comparisons were performed using Tukey test. Systems with the photoinitiator BAPO showed higher or equivalent bending values that demonstrated by the conventional system containing CQ/amine. Systems with the DFI had higher flexural values in relation to those demonstrated by systems without the DFI to CQ. Conclusion: The use of systems with alternative photoinitiators and co-initiators allows to obtain superior properties to the conventional system, making these promising systems to act both in isolation as associated with conventional systems.