Abstract

Background: In the field of esthetic restorative dentistry, Class II cavity restoration using composite resin has become a common clinical choice. To minimize microleakage, several techniques can be applied, particularly incremental layering methods, which are widely used to reduce polymerization shrinkage. However, incremental techniques require multiple clinical steps and may create voids or gaps between layers if performed improperly. The introduction of bulk–fill composite materials has provided an alternative option, allowing a thicker increment to be placed and cured in a single step, thereby reducing clinical working time. This study aimed to compare the degree of microleakage between incremental layering techniques and the bulk–fill technique for Class II composite restorations. Materials and Methods: The study was conducted on 40 extracted permanent maxillary and mandibular premolars. Standardized Class II cavities were prepared on both mesial and distal surfaces, yielding 40 cavities that were randomly divided into four groups (20 cavities per group): Group 1: bulk–fill technique; Group 2: incremental horizontal layering; Group 3: incremental vertical layering; and Group 4: incremental oblique layering. Samples underwent thermocycling and were then immersed in 2% methylene blue dye for 24 hours. Each tooth was sectioned buccolingually through the center of the restoration, and microleakage was evaluated at the gingival margin. Results: The bulk–fill group showed a significantly higher microleakage score compared to the horizontal, vertical, and oblique incremental layering groups (p < 0.05). The mean dye penetration length in the bulk–fill group was significantly greater than that in the vertical and oblique layering groups (p < 0.05). No statistically significant difference in dye penetration length was observed between the bulk–fill group and the horizontal layering group. Conclusion: The bulk–fill technique produces greater microleakage than incremental layering techniques in Class II composite restorations.

Keywords: Class II restoration, bulk–fill composite, incremental layering, microleakage.