Microleakage and retention of resin-based and bioactive giomer-based dental sealants after thermocycling: an in vitro study

Objective. This in vitro study evaluated and compared the microleakage and retention of resin-based and bioactive dental sealants after thermocycling. Methods. Forty-five extracted, caries-free premolars were randomly assigned into five groups (n = 9) according to the sealant material: two conventional resin-based sealants; Helioseal, one flowable composite; Rainbow Flow, and three bioactive sealants (Giomer-based and resin-based); BioCoat, BeautiSealant, and Beautifil Kids SA. Sealants were applied under standardized conditions and subjected to 10,000 thermocycles (5 °C-55 °C, dwell time 30 s). Microleakage was assessed using 1% methylene blue dye penetration on sectioned samples and scored (0-3). Retention was evaluated under stereomicroscopy (Score 0: complete retention; Score 1: complete loss). Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests for microleakage and Fisher’s Exact test for retention (α = 0.05). Results. Helioseal, Rainbow Flow, and BioCoat exhibited no microleakage and demonstrated complete retention (100%) post-thermocycling. Conversely, Beautifil Kids SA showed the highest level of microleakage, with significant differences noted (p = 0.0013) compared to the aforementioned sealants. Retention rates for Helioseal, Rainbow Flow, and BioCoat were 100%, while BeautiSealant and Beautifil Kids SA exhibited sealant loss in 11.11% of samples, with no statistically significant differences across the groups (p = 1.000). Effect sizes for microleakage were moderate to large, while retention outcomes showed minimal variability. Conclusion. Helioseal, Rainbow Flow, and BioCoat displayed superior resistance to microleakage. In contrast, while Beautifil Kids SA emphasizes fluoride release, it demonstrates limitations in sealing efficacy under thermal stress. Retention outcomes were similar across groups, though the study may not have been adequately powered to detect small differences. Further clinical studies are warranted to validate these findings and assess in vivo performance over time.