title: Effect of 10% sodium ascorbate on bleached bovine enamel surface morphology and microhardness.
abstract: Sodium ascorbate has recently been suggested to compensate decreased bond strength of composite resin to bleached tooth surfaces. The aim of present study was to evaluate the effect of 10% sodium ascorbate on bleached bovine enamel morphology and microhardness considering the possibility of its effect on enamel surface characteristics. A total of 69 bovine enamel slabs were prepared and mounted in acrylic resin. Subsequent to polishing, they were randomly divided into 3 groups of 23 specimens each; 3 for Scanning Electron Microscopy (SEM) analysis and 20 for hardness test. In group 1 the specimens were immersed in distilled water as control group; in group 2 the specimens were bleached with 35% carbamide peroxide for 30 min a week for 3 consecutive weeks; and in group 3 the specimens were exposed to 10% sodium ascorbate for 30 min subsequent to bleaching similar to group 1. After 3 weeks Vickers hardness of the specimens was measured at 3 points with equal distances from each other under a force of 50 g. The mean of the hardness values of each specimen was calculated and data was analyzed by one-way ANOVA (P < 0.05). The highest and lowest microhardness values were observed in group 1 and group 2, respectively. However, there were no statistically significant differences in microhardness between the groups (P = 0.12). The use of 35% carbamide peroxide alone or with 10% sodium ascorbate does not affect bovine enamel hardness. SEM analysis showed a network of sodium ascorbate adsorbed to the bleached enamel surface.
authors.affiliation: Department of Operative Dentistry, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Parnian Alizadeh
authors.initials: PA
authors.lastname: Oskoee
authors.forename: Elmira Jafari
authors.initials: EJ
authors.lastname: Navimipour
authors.forename: Siavash Savadi
authors.initials: SS
authors.lastname: Oskoee
authors.forename: Najmeh
authors.initials: N
authors.lastname: Moosavi