Evaluating Resin-Dentin Bond by Microtensile Bond Strength Test: Effects of Various Resin Composites and Placement Techniques

OBJECTIVES: This in vitro study evaluated the microtensile bond strength (MTBS) of a methacrylate-based compared to a silorane-based resin composite in Class I cavity using different placement techniques. MATERIALS AND METHODS: Class I cavities with dimension of (4 mm long, 4 mm wide, 3 mm deep) were prepared in extracted sound human molars. The teeth were randomly divided into six groups. The first three groups were filled with Filtek P90 using three methods of insertion; bulk, incremental and snow-plow, and the remaining three groups were filled with Clearfil AP-X using the same three placement techniques. After 24 hours of storage in water at 37°C, the specimens were thermocycled to 1000 cycles. Specimens were prepared for MTBS testing by creating bonded beams obtained from the pulpal floor. Statistical analysis used: Statistical analyses of data were performed by two-way ANOVA/Tukey (α=.05). RESULTS: The experiment showed significant differences between the two resin composites with regard to filling techniques (P<0.05). The MTBS was significantly higher in each of Filtek P90 subgroup compared to Clearfil AP-X ones (P<0.05). With respect to filling technique in both resin composites, bulk insertion showed the significantly lowest MTBS (P<0.05), while no significant difference was found between the outcome of incremental and snow-plow techniques (P>0.05). CONCLUSION: Silorane-based resin composite as opposed to methacrylate based resin composite and layering placements in contrast to bulk filling method had higher microtensile bond strength.