Effect of the thickness of flowable composite as intermediate layer to reduce microleakage on gingival wall

Microleakage of composite restoration in proximal composite restoration often occurs on the gingival wall. The purpose of this study is to evaluate the influence of flowable composite as an intermediate layer to reduce microleakage on the gingival wall. Thirty whole,extracted, upper premolars were divided into three groups. Within box-like cavities, the first group was restored with packable composite only. Group 2 was restored with flowable composite of a1mm thickness and then was restored with incrementally packable composite. Group 3 was restored similarly to group 2, however with a flowable composite thickness of 2mm. After thermocycling, the penetration of 1% methylene blue was investigated along the gingival wall. There were significant differences between group 1 and groups 2 and 3. No significant differences were found between groups 2 and 3. Flowable composite, as an intermediate layer, reduces microleakage of the gingival wall of proximal composite restorations. Nonetheless, the thickness of the flowable composite has no influence on the amount of microleakage observed.