An In Vitro Study Comparison of the Sealing Ability of High-Viscosity Bulk-Fill Resin Composites in Comparison with the Incremental Placement Technique

Background: Actually Resin-based composites present one of the most used restorative materials. Volumetric shrinkage due to polymerization is the most debilitating problem .Thus may result in contraction stress and subsequent microleakage and adhesion failure. Incremental layering technique has been adopted as a placement technique, in order to combat polymerization shrinkage. But this technique has certain disadvantages such as difficulty in placement of increments in small cavities, increased operational time, , interlayer contamination, incorporation of voids and difficulty in maintaining isolation. .In order to reduce the time and effort needed for layering when placing posterior composites, a novel restorative approach was appeared based on the use of high-viscosity bulk-fill composites. This technique can eliminate the possibility of voids between the layers enabling up to 4 mm increments to be cured in one step, without negatively affecting polymerization shrinkage kinetics and macromechanical properties. Aim: The aim of this in vitro study is to compare and to analyze the sealing ability of High-viscosity bulk-fill composites in comparison to incremental posterior resin composite in posterior classII restorations with the dye penetration test. Material and Methods: Seventy six classII cavities were prepared on the mesial and surfaces of 38 extracted human permanent molars, which were randomly divided into two groups: G1 (38 cavities) restorated with Single Bond 2+Reflectys TM (Itena) composite resin, G2 (38 cavities) restorated with +Single Bond2+bulk fill composite resin, The samples were then subjected to thermocycling, followed by the dye penetration test. The teeth were embedded in acrylic resin and sectioned through the restorations. The results were expressed as ordinal scores from 0 to 3 at cervical, interfacial, and enamel margins. Statistics were done with SPSS20.0 software, Student t-Test and Khi-square tests were performed. The result was considered significant at pless than0.05. Results :There were statistically significant differences between the high viscosity bulk fill resin and group and the Reflectys (Itena) composite resin in cervical and occlusal enamel interface (p0.016..) .this difference was not observed in the enamel and the interfacial regions for both groups. Conclusion: Within the limitations to this in vitro study, a significant scores were obtained with bulk-fill nanocomposite, thus material used clinically may be able to substitute the time-consuming incremental technique.