GIANINA IOVAN, CRISTINA ANGELA GHIORGHE, SIMONA STOLERIU, GALINA PANCU, IRINA NICA, IONUT TARABOANTA, SORIN ANDRIAN EFFECT OF DENTAL BLEACHING ON MARGINAL SEALING OF COMPOSITE RESIN RESTORATIONS BONDED WITH A UNIVERSAL ADHESIVE The aim of this study was to evaluate the postoperative effect of one bleaching agent containing 40% peroxide hydrogen on the interface between dental tissues and a microhybrid composite resin bonded with a universal adhesive applied in total-etch and self-etch technique. Standardized Class V restorations were performed in oral surfaces of 40 extracted human molars with the gingival margins placed bellow the cement-enamel junction. For 20 restorations the adhesive was applied with preliminary etching and for the others the adhesive was applied by using the self-etch technique. Half of the samples of each group were bleached using Opalescence Boost in one session 20 minutes-application. The sealing quality of both enamel and cervical margins of the restorations was evaluated using a microleakage test by immersion in 1% methylene blue for 24 hours. The microleakage scores were assessed using an optical microscope and the data were statistically analyzed. No statistical significant differences were recorded between the bleached and control groups and between the study groups according to the etching strategy used for bonding.