Comparative evaluation of microleakage in Class II cavities restored with snowplow technique using flowable or preheated packable bulk-fill composite resin as gingival increment by dye extraction method: An in vitro study

Context: One of the undesirable characteristics of dental composite resin is the polymerization shrinkage and the associated microleakage. The snowplow technique of placement and the preheating of the composite resins are methods to minimize microleakage. Aim: The aim of this study was to comparatively evaluate microleakage in Class II cavities restored with snowplow technique using either preheated packable or flowable bulk-fill composite resin. Methodology: Fifty sound first molars were selected. Class II mesio-occlusal box preparations were made. The test specimens were randomly divided into two groups. Group 1: Tetric N-Flow Bulk Fill and Tetric N-Ceram Bulk Fill co-cured in snowplow technique. Group 2: Tetric N-Ceram Bulk Fill preheated to 60°C and Tetric N-Ceram Bulk Fill co-cured in snowplow technique. Restored teeth were processed for dye extraction. Statistical Analysis: Mann-Whitney U-test was applied to compare the microleakage between the groups. Results: Results indicate that specimens in Group 2 showed lower microleakage (median 0.041750) when compared to specimens in Group 1 (median 0.059400). Conclusion: The results imply that the preheated packable bulk-fill composite resin showed less microleakage as compared to flowable composite while restoring Class II cavities by the snowplow technique. Keywords: Bulk fill, dye extraction, microleakage, preheating, snowplow