The Comparison of Shear Bond Strength of Self-cured and Light-cured Composite Restorations to Dentin, Using a Universal Bonding System

Introduction: To evaluate and compare shear bond strength of self-cure and  light-cure composites using a universal bonding system. Materials and Methods: Superficial coronal dentin of 62 intact extracted  premolars was exposed and bonding agent (All-Bond Universal) was applied over the  dentin surface according to the manufacturer instruction (self-etch mode). Then  samples were distributed in 2 groups (n=31), and composite cylinders were built using AELITE All-purpose Body Light-cure composite (group I) and MasterDent Self-cure composite (group II). Samples were kept in distilled water at room temperature for one week and then were thermocycled (500 cycles, 5 º C to 55º C). Finally, samples were mounted in acrylic molds and shear bond strength was assessed using a Universal Testing Machine  at the crosshead speed of 0.5 millimeter per minute. Stereomicroscope was used to determine the failure mode. Bond strength data were analyzed using sample t-test and frequencies of failure types analyzed using Chi-square test. Results: Mean shear bond strength in group I (34 ± 3.56Mpa) was higher than group II (32±3.24Mpa). In addition, the prevalence of adhesive failure in group II (74.2%) was higher than group I (67.7%). However, these differences were not statistically significant. Conclusion: Our findings showed that the application of All-Bond Universal  followed by a self-cured composite without using a separate self-cure activator on  dentin, provides bond strength values comparable to that of a light-cured composite.