ABSTRACT The research objective was the effect on the surface microhardness of human dental enamel exposed to two bleaching agents and subjected to the action of sodium fluoride. Two bleaching agents were employed; 35% hydrogen peroxide and 35% carbamide peroxide. 25 agents were used by the bleaching agent, taking into account the inclusion and exclusion criteria. Subsequently using a low speed handpiece these teeth were separated from the root crown which used a carbide disc, and the sound was given a finished type on each surface. Each enamel fragment was placed in a ring made of plastic tube with 2.0 cm in diameter incorporating a self-curing polyester resin, called a probe. Each enamel fragment was then exposed to the bleaching agent based on 35% carbamide peroxide (Opalescence Ultradent) for 30 minutes; and 35% hydrogen (Whiteness HP Maxx-FGM) for 45 minutes respectively. The microh...