Microleakage of Posterior Restorations: Effect of Different Shades of Flowable-Composite

Objective:This in vitro study evaluated the effect of using different shades of flowable composite in the form of gingival increment on microleakage of posterior composite restorations.Methods:Standardized box-shaped class II cavities, 3mm in width, 2mm in depth, and extended 1mm apical to the CEJ, were prepared on thirty six freshly extracted sound human premolars. In all specimens Clearfil SE Bond system (Kuraray Medical Inc, Japan) was used according to the manufacturer's instructions. The prepared teeth were then randomly divided into 6 groups. The flowable composite resin (Bisco Co., USA) shades A1, A2, A3.5, C2, and D3 were used as the first increment in the gingival portion of groups 1 to 5, respectively. In the last group the flowable composite was not applied. The rest of the cavities were restored with hybrid composite A3 (Bisco Co., USA), incrementally, then polished. After 24 hours of immersion in distilled water, the specimens were thermocycled (500 cycles, 5-55 , 30 seconds of dwell time), sealed with nail polish and immersed in 2% basic fuschin solution for 24 hours. The restorations were sectioned longitudinally, and microleakage was evaluated using a 0-3 score scale. Data were analyzed with Kruskal-Wallis Non-Parametric Analysis of Variance (ANOVA) followed by the Mann-Whitney U test at a significance level of p<.05.Results:According to Kruskal-Wallis test, no statistically significant difference were observed between study groups (p<.056). However, Mann-Whitney U test showed statistically significant differences between first and sixth groups and also between first and fifth groups (p<.05). The application of flowable composite as gingival increment may be the reason for the decreased gingival microleakage in study groups compared to the control group for which no such increment is applied.Conclusions:The application of flowable composite with lower chroma such as A1 shade in posterior composite restorations might be recommended.