Interfacial gaps following ceramic inlay cementation vs direct composites.
This study compared the interfacial integrity of Class II ceramic inlay restorations and direct resin composite restorations. The influence of a flowable resin composite liner was also evaluated. Class II DO cavities were prepared in 40 recently extracted mandibular molars and assigned to four treatment groups. Group A: direct composite restoration; Group B: Cerec inlays fabricated and cemented with a resin cement; Group C: adhesive lining with a flowable resin composite used prior to resin composite restoration; Group D: lining with a flowable resin composite prior to cementation of Cerec inlays. After finishing, polishing and thermocycling (4 degrees C and 60 degrees C x 500), the samples were cross-sectioned in a mesio-distal direction along the center of the fillings or inlays. The cross-sectioned surface was polished, and the adhesive interfaces between resin and enamel or dentin were observed under a scanning laser measurement microscope. Ceramic inlay restorations showed no interfacial gaps in enamel, but direct resin composite restorations showed a significantly higher incidence of gaps at the interface or cracks in the interfacial enamel (p=0.0002). No differences were found in the resin-dentin interfaces for both the inlay and direct resin composite restorations. The use of a flowable resin composite as an adhesive liner produced a significantly greater gap-free resin-dentin interface in Cerec inlay and direct resin composite restorations (p=0.0233 & 0.0009), but it did not reduce gap formation at the resin-enamel interface.