Role of oxygen inhibited layer on shear bond strength of composites

Background and Aim: Rising demand for aesthetic adhesive restorations has led to wide use of composites. A multilayer technique is recommended for success of these restorations. The surface layer of composite coming in contact with air forms a superficial sticky layer called oxygen inhibited layer, upon polymerization, allowing resins from both sides to cross the interface and form an interdiffusion zone. The present study was sought to test whether oxygen inhibited layer increases or decreases the shear bond strength at the interface of composites. Materials and Methods: A microhybrid composite Esthetic -X (Dentsply, Caulk) was used in this study. A cylindrical mold of composite, five mm thick and eight mm long, was prepared and embedded in acrylic resin molds after curing. This was placed in distilled water for two hours and sheared in universal testing machine at a cross head speed of one mm/sec. Statistical Analysis: Data analyzed statistically to determine the significant difference between the groups. Mean and standard deviation values were estimated for the study groups and compared by one way ANOVA. Results: No significant difference in shear bond strength of composites cured with and with out oxygen inhibited layer. Conclusions: The presence or absence of oxygen inhibited layer made no significant difference in shear bond strength of composite resins.