Clareamento dental com peróxido de hidrogênio 40% com diferentes phs: avaliação da eficácia, morfologia do esmalte e penetração na câmara pulpar

Abstract

The present study evaluated the efficacy, enamel surface morphology and concentration of hydrogen peroxide in the pulp chamber of human teeth submitted to 40% hydrogen peroxide bleaching gels (Opalescense Boost, Ultradent) modified by the manufacturer with different pHs. Forty premolars were used for the evaluation of the efficacy and penetration of hydrogen peroxide in the pulp chamber, these were divided into 4 groups (n = 10): control (exposed to distilled water); pH 5.1 (exposed to pH 5.1 bleaching agent); pH 6.3 (exposed to pH 6.3 bleaching agent) and pH 7.0 (exposed to pH 7.0 bleaching agent). The teeth were sectioned leaving 3 mm of root, the pulp tissue was removed and an acetate buffer was placed in the pulp chamber. The bleaching gel was applied in one session according to manufacturers recommendations (two applications of 20 min each). After the bleaching procedure, the buffer was removed and leucocrystal violet and peroxide enzyme were added. The optical density of the solution was determined on UV-VIS spectrophotometer (Carry 50, Varian) and converted to the equivalent concentration (μg/mL) of the hydrogen peroxide. The efficacy was assessed using the CIELab system by means of a digital spectrophotometer (Easyshade Advance 4.0,VITA) before and one week after the bleaching treatment. Five additional premolars were divided into the vestibular-lingual and mesio-distal, resulting in four parts, which were divided in the four experimental groups and analyzed by scanning electron microscope (VEGA3, TESCAN). Data was submitted to ANOVA and Tukey’s test (α = 0.05). The bleaching agent with pH 5.1 presented the highest concentration of hydrogen peroxide in the pulp chamber (p < 0.001) and evident morphological alterations such as porosities and irregularities on the enamel surface. Bleaching gels of pH 6.3 and pH 7.0 showed similar hydrogen peroxide concentrations and similar morphology.