In vitro evaluation of microleakage in Class II composite restorations: High-viscosity bulk-fill vs conventional composites

This study compared marginal microleakage of Class II cavities restored with bulk-fill resin (Filtek (TM) Bulk Fill) and conventional composite resin (Filtek (TM) Supreme XTE). Two standardized Class II cavities were prepared in forty extracted human molars. The gingival margin was located above the cemento-enamel junction for twenty molars (groups 1 and 2) and apically for the other twenty (groups 3 and 4) (n=20). The occlusomesial cavity was filled with bulk-fill resin by insertion in bulk (groups 1 and 3) and the occlusodistal cavity was restored with conventional composite using incremental technique (groups 2 and 4). The teeth were thermocycled (500 cycles 5-55 degrees C), stained and observed under light microscope. The microleakage was significantly lower in gingival margins located in enamel compared with dentin margins (p