Sealing ability of occlusal resin composite restoration using four restorative procedures

The purpose of this work was to investigate fluid flow after restoration using four restorative procedures. Micro-gap, internal dye leakage, and micropermeability of bonded interfaces were also investigated. Each tooth was mounted, connected to a fluid flow-measuring device, and an occlusal cavity was prepared. Fluid flow after cavity preparation was recorded as the baseline measurement, and the cavity was restored using one of four restorative procedures: bonding with total-etch (Single Bond 2) or self-etch (Clearfil SE Bond) adhesives without lining; or lining with resin-modified glass-ionomer cement (GIC) (Fuji Lining LC) or conventional GIC (Fuji IX) and then bonding with the total-etch adhesive. Fluid flow was recorded after restoration and at specific time-points up to 6 months thereafter and recorded as a percentage. Micro-gap formation was analyzed using resin replicas and scanning electron microscopy. Internal leakage of 2% methylene blue dye was observed under a light microscope. In micro-permeability testing, fluorescent-dye penetration was investigated using confocal laser microscopy. None of the restorative procedures provided a perfectly sealed restoration. Glass-ionomer lining did not reduce fluid flow after restoration, and micro-gaps were frequently detected. The self-etch adhesive failed to provide a better seal than the total-etch adhesive, and even initial gap formation was rarely observed for the former. Penetration of methylene blue and fluorescent dyes was detected in most restorations.