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.