Effect of sodium ascorbate on surface microhardness of bleached enamel

Abstract

Recently sodium ascorbate has been recommended for reverse of the reduced bond strength after bleaching of teeth. The purpose of this study was to investigate the effect of a chemical agent, 10% sodium ascorbate, on surface microhardness of bleached enamel. Methods and Material: 60 enamel slabs measuring 3 3 2 mm were obtained from the bovine crowns using a double sided diamond disk. Then the teeth were mounted in a self cure acrylic resin and were wet polished with soflex discs. The specimens were randomly divided into three groups, each group included 20 specimens , as follows: 1- Specimens were bleached with 35% carbamide peroxide gel for 30 min/w, for 3 weeks. 2- Specimens were bleached simillary group 1 and then were treated with 10% sodium ascorbate solution for 30 min . 3- control (no treatment, stored in distilled water). After three weeks microhardness of each specimens was measured and recorded by hmw- 2000 shimadzu mashin in Vickers hardness and at room temperature. The data were analyzed by one way ANOVA (P<0.05). Results: The highest mean of microhardness (365.2930.59) was for group 3 and the lowest was for group 1 (347.7224.26); however, no significant changes were recorded in mean of enamel surface microhardness between three groups (P=0.12). Conclusion: Use of 35% carbamide peroxide as alone or with 10% sodium ascorbate has no effect on bovin 's enamel microhardness.