Long-term marginal sealing stability of bioactive restorative materials in class V cavities evaluated by micro-CT

Microleakage at the tooth–restoration interface is a primary cause of restoration failure in Class V cavities. This study aimed to evaluate and compare the long-term microleakage performance of three bioactive restorative materials — including one applied with and without an adhesive system — and a conventional universal composite resin. Specifically, we investigated whether bioactive materials maintain marginal sealing stability comparable to conventional composite resin over 1-year and 5-year simulated aging periods assessed by micro-computed tomography. Ninety sound human upper molars received standardized Class V cavities and were restored with Cention N (alkasite restorative, with and without adhesive), Activa Bioactive Restorative (bioactive ionic resin-based restorative), GC Equia Forte HT (glass hybrid restorative), or G-aenial A’Chord (nanohybrid composite resin, control). Specimens were subjected to 10,000 or 50,000 thermocycles corresponding to 1-year and 5-year simulated aging. Silver nitrate-enhanced micro-computed tomography was used for three-dimensional volumetric quantification of microleakage. Data were analyzed using the Kruskal-Wallis test with Dunn’s post hoc test and Mann-Whitney U test with Bonferroni correction. No significant differences were observed among groups after 1-year simulated aging. After 5-year simulated aging, GC Equia Forte HT exhibited significantly greater microleakage compared to all other materials and showed a significant increase relative to its own 1-year values. All remaining materials maintained stable microleakage volumes throughout the observation period. These findings indicate that the bioactive resin-based materials and the conventional composite maintained adequate marginal sealing throughout the observation period, whereas GC Equia Forte HT showed compromised marginal seal after extended aging. Bioactive resin-based materials demonstrated long-term marginal sealing stability comparable to conventional composite resin, whereas the glass-hybrid ionomer system showed progressive interfacial deterioration under prolonged thermocycling. The long-term sealing stability of bioactive resin-based restorative materials supports their use in Class V cavities, particularly in high-caries-risk patients who may benefit from ion-releasing remineralization capacity. Glass-hybrid ionomer systems such as GC Equia Forte HT may require closer clinical follow-up when used in long-term Class V restorations, and further clinical studies are warranted before definitive recommendations regarding their suitability for this indication can be made.