Comparison of Internal Adaptation of Composite Restorations With Different Liners

Objectives: Objectives: The goal of this study was to compare the internal adaptation of composite restorations in Class I cavities with or without an intermediate liner.
Methods: Methods: Class I cavities were prepared in extracted human third molars. They were treated with a one-step self-etch adhesive (G-Premio Bond, GC). In the control group (n=7), Tetric EvoCeram Bulk Fill (TBF, Ivoclar Vivadent) was placed using the bulk fill technique and then light-cured. In the experimental groups (n=7 for each group), six different liner materials were applied and light-cured: for group BFF with the flowable composite of Beautifil Flow F02 (Shofu); for group EFQ with Estelite Flow Quick (Tokuyama); for group FTF with Filtek Z350XT flowable (3M); for group SDR with SDR bulk fill flowable (Dentsply); and for group GCL with a RMGI (resin modified glass-ionomer) cement of Fuji lining LC (GC). TBF was filled onto the liner and light-cured. After thermo-cycling, cross sectional images were taken by swept-source optical coherence tomography (SS-OCT) device (Santec OCT-2000). Internal adaptation was measured on the SS-OCT image and compared in terms of high brightness percentage (HB%) values to represent the microgap. High HB% indicates poor internal adaptation. HB% of all groups was compared using one-way ANOVA (analysis of variance) and Tukey’s post hoc test.
Results: Results: Groups with an intermediate liner showed superior internal adaptation to control group. Internal adaptation (HB%) was different depending on the liner material: SDR, TBF ≤ GCL ≤ BFF, FTF, EFQ (one-way ANOVA, p<0.05).
Conclusions: Conclusion: In Class I cavities, an intermediate liner improved internal adaptation of the composite restoration.