Effect of aging on cavity adaptation of Class V cavities restored with bioactive restorative materials: a Micro-CT and SEM analysis

This in vitro study evaluated the effect of aging on cavity adaptation (marginal vs. interfacial) of Class V cavities restored with bioactive restorative materials using micro-computed tomography (micro-CT) and scanning electron microscopy (SEM). Thirty-six sound human molars received two standardized Class V cavities on the buccal and lingual surfaces. Teeth were randomly assigned to three restorative groups ( N = 24): conventional microhybrid composite (Filtek Z250, Group FZ), bioactive alkasite (Cention Forte, Group CF), and bioactive hybrid composite (Activa Bioactive Restorative, Group AC). Each group was subdivided into non-aged and aged subgroups ( n = 12). Aging was performed in artificial saliva using 10,000 thermal cycles (5–55 °C) and 100,000 chewing cycles (85 N). Interfacial and marginal gap formation (GF) volumes (mm 3 ) were quantified by micro-CT. Marginal adaptation was additionally evaluated by SEM in representative specimens per group. Statistical analyses were performed using linear mixed models and Bonferroni tests ( p < 0.05). Both non-aged and aged Groups FZ exhibited significantly lower interfacial GF in coronal and cervical regions compared with bioactive groups ( p < 0.05). For non-aged and aged Groups FZ, significantly higher interfacial GF in the coronal region was observed compared with those in the cervical region ( p < 0.05). Moreover, a significant increase in cervical interfacial GF was observed in Group CF after aging ( p < 0.05). Finally, aged Group FZ showed a decrease in marginal GF compared with non-aged Group FZ ( p < 0.05) with aging in the dentin. Representative SEM observations qualitatively supported the micro-CT findings. Bioactive alkasite materials in Class V cavities after aging demonstrated inferior interfacial performance compared with a dual-cure bioactive hybrid composite, particularly in cervical regions. Aging resulted in increased interfacial GF along the cervical walls in this group, whereas marginal GF remained stable.