Effect of different application strategies of universal adhesive used for immediate and delayed dentin sealing on the microtensile bond strength of self-adhesive resin cement to dentin with and without aging

Abstract

Background and aim: The bond strength in restorations is an important aspect that should be given special attention. In the recent years the immediate dentin sealing technique has been proposed. Therefore, this study aimed to investigate the effect of different application strategies of universal adhesive in immediate and delayed dentin sealing on the microtensile bond strength of self-adhesive resin cement to dentin with and without aging. Materials and Methods: In this experimental study, 240 samples (cut off form 24 healthy human third molar teeth) were collected. The samples were prepared after removing the enamel and exposing the dentin. Then the samples were cut in to 1×1 mm2 bars and 10 samples were obtained from each tooth. The samples were randomly divided into two groups (n=120) based on the universal adhesive (All-Bond Universal) application strategy: etch and rinse or self-etch. Each group further divided into two subgroups (n=60): immediate dentin sealing (IDS) or delayed dentin sealing (DDS). Then the composite blocks were cemented to samples using self-adhesive resin cement. The microtensile bond strength of half of the samples in each subgroup (n=30) was tested one week after cementation of the composite blocks. The other half of the samples (n=30) were tested after 10,000 thermocycling to investigate the effect of aging on bond strength. The three-way analysis of variance was used to compare the bond strength between the groups and subgroups. Statistical significance was set at P<0.05. Results: There was a significant difference in mean microtensile bond strength values between the two bonding strategies. The mean microtensile bond strength value in the etch and rinse strategy was higher compared to that in the self-etch strategy. There was a significant difference in mean microtensile values between IDS and DDS groups. The mean microtensile bond strength value in IDS subgroup was higher compared to DDS subgroup. There was a significant difference between the aged and non-aged subgroups. The mean microtensile bond strength value in the aged subgroup was lower compared to that in the non-aged subgroup. There was an interaction between the bond strategy, sealing and aging. In other words, the effect of aging on the mean microtensile bond strength in IDS and DDS subgroups was not the same between the two strategies. Conclusion: Immediate dentin sealing improved the microtensile bond strength in All-Bond Universal adhesive. Etch and rinse strategy resulted in higher bond strength. Aging decreased the bond strength.