In vitro evaluation of the microhardness of human enamel exposed to the acid solution after bleaching

Abstract

Introduction: Acid erosion is the superficial loss of enamel caused by chemical processes that do not involve bacteria. Intrinsic and extrinsic factors, such as the presence of acid substances in the oral cavity, may cause a pH reduction, thus potentially increasing acid erosion. Objective: Aim of this study was to evaluate the microhardness of bleached and unbleached human enamels after the immersion in a soft drink for 7 and 14 days. Materials and Methods: Thirty freshly extracted human teeth were used in the experiment. The specimens were submitted to initial microhardness measurement. The specimens of groups non-hydrogen peroxide and hydrogen peroxide, each of which was exposed to one of the respectively assigned acid solutions for 5 minutes and stored in artificial saliva for 23 hours and 55 minutes to complete a period of 24 hours. This process was repeated for 7 days in a row, where all the specimens were submitted to microhardness measurement. Results: The main effects of enamel microhardness revealed the statistical significance of the bleaching agent, as a greater microhardness mean value was observed for the unbleached condition, as compared with the bleached condition.

Keywords

• Bleaching
• enamel
• human enamel
• microhardness