Effect of Various Resin Cements as Liner on the Microleakage of Restored Composite Class II restoration Using Closed Sandwich Technique

Aim: Gingival margins of posterior composite restorations is usually more apical compared to CEJ. The present study was aimed to determine the microleakage in gingival margins of Class II composite restorations through using three different types of resin cements as liners. Materials and Methods: In this in-vitro study, two mesial and distal Class II cavities with 1mm gingival margins were created under CEJ on 24 healthy human premolar teeth. The teeth were randomly divided into four groups: Group 1: Rely X Unicem liner, Group 2: PAN F2 liner, Group 3: RMGI liner, and Group 4: the control group where no liner was used. Then, teeth were restored using SE bond and Z-250 composite. The teeth were placed in 2% fushin solution after 24 hours of thermocycling. Then, the teeth were cut mesiodistally in order to analyze the microleakage under stereomicroscope. Statistical data were analyzed at significance level of 0.05 using SPSS version 16 by Kruskal-Wallis and Mann-Whitney statistical tests. Results: Microleakage of cavities in experimental groups were significantly different (p<0.05). Groups 1 and 3 had significantly lower microleakages compared to group 2 (p<0.05). However, these two groups had no significant difference with each other (p=0.590). Conclusion: Placing liner in posterior composite restorations reduced microleakage significantly compared to the control group. RXU and RMGI cements had similar effects on reducing microleakage and had significantly lower microleakage than PAN F2 cement.