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VOLUME 8 , ISSUE 3 ( March, 2007 ) > List of Articles


Effect of Different Time Periods of Vital Bleaching on Flexural Strength of Bovine Enamel and Dentin Complex

Marjaneh Ghavamnasiri, Sara Abedini, Alireza Mahdizadeh Tazangi

Citation Information : Ghavamnasiri M, SA, Tazangi AM. Effect of Different Time Periods of Vital Bleaching on Flexural Strength of Bovine Enamel and Dentin Complex. J Contemp Dent Pract 2007; 8 (3):21-28.

DOI: 10.5005/jcdp-8-3-21

License: CC BY-NC 3.0

Published Online: 01-05-2008

Copyright Statement:  Copyright © 2007; The Author(s).



The aim of this in vitro study was to evaluate the effect of 20% carbamide peroxide (CP) on the flexural strength (FS) of bovine enamel and dentin complex.

Methods and Materials

One hundred sound bovine teeth were selected for use. Blocks (2×3×8 mm) from the middle portion of the facial surfaces of each crown were sectioned from the teeth. The specimens were randomly divided into five groups (n=20) based on the time period of vital bleaching. Group 1 comprised the control group kept in artificial saliva. The experimental groups subjected to immersion in 20% CP, Opalescence, for four, six and eight weeks, respectively (eight hours daily). Mechanical testing was performed 24 hours after the last treatment using an Instron Universal Testing Machine with a crosshead speed of 0.5 mm/min. The results were analyzed by one-way analysis of variance (ANOVA) and Tukey's test (α=0.05).


Mean values for FS were 141.27, 103.06, 120.71, 130.23, and 117.90 (Mpa), respectively. Statistically significant differences in FS were noted among the groups. A statistically significant difference was observed between Group 2 (two week bleach) and the control.


Application of 20% CP bleach for two weeks provided significant decreases in FS of bovine enamel and dentin complex. Similar decreases were not observed among the other groups.


Ghavamnasiri M, Abedini S, Tazangi AM. Effect of Different Time Periods of Vital Bleaching on Flexural Strength of Bovine Enamel and Dentin Complex. J Contemp Dent Pract 2007 March;(8)3:021-028.

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