Effect of 10% Sodium Ascorbate on Bleached Bovine Enamel Surface Morphology and Microhardness

Parnian Alizadeh Oskoee1, Elmira Jafari Navimipour1 , *, Siavash Savadi Oskoee 1, Najmeh Moosavi 2
1 Department of Operative Dentistry, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran
2 Department of Prosthodontics, Faculty of Dentistry, Ahvaz University of Medical Sciences, Ahvaz, Iran

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© Oskoee et al.; Licensee Bentham Open.

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* Address correspondence to this author at the Department of Operative Dentistry, Tabriz School of Dentistry, Golgasht Street, Daneshgah Avenue, Tabriz, Post Code: 5166614713, Iran; Tel: 0098 4113355965-6; Fax: 0098 4113346977; E-mail: or


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.

Keywords: Enamel, Sodium Ascorbate, Carbamide Peroxide, Microhardness, Morphology.