RESUMEN
The study was carried out to evaluate and compare dentine margin microleakage of nano-filled resin composite restorations placed with a RMGIC using the co-cure technique and those placed with an 'all-in-one' self-etch DBA. In premolar teeth, that had to be extracted for orthodontic reasons, two proximal boxes with gingival margins placed in dentine were prepared. Restorations were inserted using co-cure method with RMGIC plus a nano-filled resin composite in one proximal box, and self-etch DBA plus nano-filled resin composite in other proximal box. After two weeks, teeth were extracted and was sectioned mesio-distally. The dye leakage length was measured using a stereomicroscope. The mean value of microleakage for co-cure technique was found to be lesser than that for all-in-one dentine bonding agent. Co-cure technique was found significantly superior to all-in-one DBA in its sealing ability at gingival margin