The effect of flowable composite lining thickness with various curing techniques on microleakage in class II composite restorations: an in vitro study.

AIM Aim of this study was to compare class II composite restoration using flowable composites as lining with various thickness and curing techniques by evaluating cervical marginal microleakage. MATERIALS AND METHODS Fifty intact molars, each prepared with two box-only class II cavities, were randomly divided into five groups: Group I, P60 filling alone; group II, ultrathin flowable composite lining (0.5-1mm) cocured with overlying composite; group III, thin lining (1-1.5) cocured with overlying composite; group IV, ultrathin lining (0.5-1 mm) precured and group V, thin lining (1-1.5) precured. The teeth were then thermocycled for 1500 cycles (between 5 and 60 °C) and immersed in dye for 24 hours. Cervical microleakage was measured as the extent of dye penetration. RESULTS Cocured specimens (groups II and III) showed least microleakage and control specimens (group I) showed maximum microleakage. On comparison of curing techniques, cocured specimens (groups II and III) showed less microleakage than precured (groups IV and V). On comparison of lining thickness and type of curing, group IV showed less microleakage than group V. Groups II and III were statistically not significant. CONCLUSION It was concluded from the results that ultrathin cocured flowable composite lining specimens improved the marginal sealing with decreased microleakage. CLINICAL SIGNIFICANCE In this study, the application of additional flowable composite lining with various thicknesses presented different influences in marginal quality of class II box only composite restorations. A new technique applying an ultrathin flowable composite lining with cocuring technique improved the marginal sealing with decreased microleakage. Restorations with thin lining presented reduced marginal integrity after thermocycling.