Comparing Microleakage Between Bulk- Fill Composites (Flowable, Packable) and Conventional Light-Cured Composite in Class II Cavities

Compared to conventional composites, bulk-fill composites increase polymerization depth and contraction stress, and reduce cuspal deflection. Therefore, it is claimed that their microleakage is reduced. This study aimed to compare the microleakage of bulk-fill composites (flowable and packable) with conventional light-cured ones. Materials and Methods: This in vitro experimental study was done on 60 human extracted premolars. We made standard Class II cavities (4 mm in height, 3 mm in length buccolingually, and 1.5 mm in axial depth) in the teeth. The teeth were randomly divided into three groups based on the type of composite: group I consists of packable bulk-fill (x-tra fill packable; VOCO Company) composite, group II with flowable bulk-fill (x-tra base; VOCO Company), and group III with conventional composite (Grandio; VOCO Company). The total-etch bonding system (the 5th generation) was applied in all cavities. After restoration, the teeth were thermocycled. Finally, the microleakage rate was evaluated using a stereomicroscope. The data were analyzed using the Chi-square test (α=0.05) in SPSS. Results: The results indicated no statistically significant difference between enamel and dentinal margins in bulk-fill packable and conventional composites (P=0.06). In the bulk-fill flowable group, dentinal margins had greater dye penetration to the enamel margin in the axial surface (P<0.05). There was no significant difference between the three groups in terms of marginal microleakage of enamel and dentin (P<0.05). Conclusion: Using bulk-fill flowable composites on the dentinal cavity is not suitable with the thickness recommended by the manufacturer. To prove these results, we need to design and perform long-term in vitro and in vivo studies. The use of the incremental technique for placement of composites, even with the bulk-fill group sounds to be more logical.