| dc.description.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. | |
