Evaluation of the effects of the oxygen-inhibited layer on shear bond strength of two resin composites

AIM: The rising demand for aesthetic adhesive restorations has led to the wide use of composites. Multilayer techniques are recommended for the success of these restorations. However, this technique of layering causes the problem of interlayer adhesion, thus supporting the influence of the oxygen-inhibited layer. This study sought to test the hypothesis that the oxygen-inhibited layer increases the shear bond strength of composite resin by allowing the resins on both sides to cross the interface and form an interdiffusion zone. MATERIALS AND METHODS: A microhybrid composite resin, Charisma, and a nanofill composite resin, Solare, were used in this study. Cylindrical specimens of the composites of 5 mm diameter and 6 mm height were prepared and embedded in acrylic resin moulds after curing. Curing was done in an argon atmosphere to prevent the formation of the oxygen-inhibited layer. To clinically simulate an inert atmosphere, a cellophane matrix strip was used during the process of curing. RESULTS: Shear bond strength of the specimens was tested using a universal testing machine and the results were tabulated and statistically analyzed.