Microleakage Assessment of Bulk-Fill Composites in Primary Molars Using Micro-CT Analysis

Objective: This study aimed to evaluate and compare the microleakage of different bulk-fill restorative materials in Class II cavities of primary molars using high-resolution micro-computed tomography (micro-CT).Materials and Methods: Fifty standardized mesio-occlusal and disto-occlusal Class II cavities were prepared and restored in extracted, intact primary molars using five restorative materials: SDR, Tetric EvoCeram Bulk-Fill, VisCalor Bulk, Cention N, and Dyract XP.All restorations were finished, polished, and subjected to thermocycling of 1000 cycles.Microleakage was assessed via silver nitrate dye penetration and quantified using micro-CT imaging.The microleakage was analyzed using one-way ANOVA with Tukey's test applied for pairwise comparisons.The significance threshold was established at 5% (p = 0.05).Results: All tested materials demonstrated similar microleakage patterns, with mean penetration ratios ranging from 0.569 to 0.673.No statistically significant differences were found among the five groups (p>0.05).Conclusion: All tested bulk-fill materials exhibited comparable microleakage performance in primary molars.The results suggest that when proper adhesive protocols and techniques are followed, modern bulk-fill composites, including thermoviscous and alkasite materials, can provide effective marginal sealing in pediatric restorative procedures.