Microleakage difference between bulk and incremental technique on bulk fill resin composite restoration (in vitro study)

Polymerization shrinkage is one major drawback of composite resin as dental restoration material. Polymerization shrinkage can cause microleakage that may impact on the occurence of secondary caries. Incremental placement technique has been widely suggested as an attempt to minimize polymerization shrinkage. Meanwhile, developments in dentistry has led to bulk fill composites that can be used up to a thickness of 4 mm with less polymerization shrinkage compared with conventional composites. Aim: To determine microleakage difference between bulk and incremental technique on bulk fill resin composite restoration. Cavity depth of 4 mm with diameter of 2 mm were made on two sample groups, each group consisted of 12 premolars. Group 1 with bulk technique (4 mm) and group 2 with incremental technique of 2 layers (2 mm) horizontally. Samples were submesed in 0.3% methylene blue for 24 hours. Samples were cut in bucco-lingual direction and microleakage determined with scoring system. There were significant differences between sample groups (p < 0.05). In general, microleakage produced by incremental technique was smaller than bulk technique. Incremental technique on bulk fill resin composite restoration creates less microleakage than bulk technique.