Influence of the Type of Bulk-Fill, Resin-Based Composite on Internal Adaptation in Class V Restorations.

OBJECTIVE: To investigate the effects of bulk-fill, resin-based composite types (high or low viscosity) on the internal adaptation of Class V restorations. STUDY DESIGN: Experimental study. Place and Duration of the Study: Hefei Stomatological Hospital, Hefei, China, from October 2022 to December 2023. METHODOLOGY: A total of 140 extracted human premolars were collected. Class V cavities were prepared on the buccal surface of each tooth, which was randomly divided into seven groups (n = 20). Cavities were restored by two low-viscosity and three high-viscosity bulk-fill resin-based composites or two conventional resin-based composites. All the samples were artificially aged. The percentage of debonding formation (D%) was calculated at baseline and 6 months later using optical coherence tomography (OCT). The OCT data were statistically analysed using one-way ANOVA, and the effects of composite type and artificial ageing were analysed via two-way ANOVA. RESULTS: For Class V restorations, two low-viscosity bulk-fill resin-based composites generated significantly lower D% (p <0.05). Two-way ANOVA revealed that both composite type and artificial ageing significantly influenced internal adaptation (p <0.05). CONCLUSION: The low-viscosity bulk-fill resin composites demonstrated better internal adaptation both before and after artificial ageing. KEY WORDS: Bulk-fill resin composite, Debonding formation, Artificial ageing, Optical coherence tomography, Class V.