Evaluation of human enamel permeability exposed to bleaching agents

AIM: To evaluate the human enamel permeability after different external bleaching techniques. METHODS: The coronal portions of 20 maxillary human incisors were covered with an acid resistant varnish, except the labial surface, to prevent dye penetration of silver nitrate. The specimens were divided randomly into four groups (n=5) according to the bleaching treatments: Group 1 (G1) - without bleaching agent (control group), Group 2 (G2) - 35% hydrogen peroxide (HP) - one session of three 10-min applications, Group 3 (G3) - 35% HP - 2 sessions of three 10-min applications, and Group 4 (G4) - 6% ...