MICRO-CT ANALYSIS OF MICROLEAKAGE IN BULK-FILL COMPOSITE RESTORATIONS: CONVENTIONAL PLACEMENT VERSUS STAMP TECHNIQUE

Purpose: This study aimed to assess the microleakage in Class I bulk-fill composite by comparing the conventional bulk-fill technique versus the stamp technique, using micro-computed tomography. Materials and Methods: Twenty-four caries-free permanent molars, extracted for orthodontic reasons, were prepared with standardized Class I occlusal cavities (4 mm deep, 5 mm mesiodistal, 4 mm buccolingual) and randomly assigned to two groups (n=12 each): Group 1 (conventional bulk-fill with Tetric EvoCeram Bulk Fill) and Group 2 (stamp technique with the same composite). Both groups followed the same adhesive protocol (37% phosphoric acid etching, Adhese Universal VivaPen, and light-curing at 1000 mW/cm²). Group 1 restorations were manually shaped and cured, with glycerin gel applied to eliminate the oxygen-inhibited layer, while Group 2 used a pre-restorative occlusal stamp for anatomy replication. Specimens underwent 1000 thermocycling cycles (5°C–55°C) to simulate aging, followed by immersion in a 50% silver nitrate solution for microleakage tracing. Micro-computed tomography analysis quantified silver nitrate penetration at the resin-tooth interface, and data were analyzed and compared. Non-parametric Mann-Whitney U test (α = 0.05) was used to compare the amount of penetrated tracer. Results: Mean volume of penetrated tracer was 0.053 ± 0.031 for Group 1 and 0.057 ± 0.028 for Group 2, with no statistically significant difference (p<0.05). Conclusion: Both techniques demonstrated comparable microleakage, suggesting that the stamp technique is a viable alternative for Class I restorations, offering efficient occlusal anatomy replication without compromising marginal integrity. Further in vivo studies are needed to validate clinical performance.