The results of this meta- analysis showed no significant changes in enamel microhardness when using the 10 % carbamide peroxide bleaching gel over periods of 7 , 14 and 21 days
Several studies have investigated the effect of bleaching on dental tissues .
The evaluation of the effect of home bleaching with 10 % carbamide peroxide is important for assessing alterations in enamel microhardness that may affect dental health in terms of resistance to masticatory forces .
This meta- analysis was performed in order to determine scientific evidence regarding the effects of home vital bleaching with 10 % carbamide peroxide gel on the microhardness of human dental enamel .
Effect of tray-based and trayless tooth whitening systems on microhardness of enamel surface and subsurface.
PURPOSE To evaluate the effect of tray-based and trayless tooth whitening systems on  surface and subsurface microhardness of human enamel . METHODS Enamel slabs were obtained from recently extracted human third molars . Specimens were r and omly assigned to six groups according to tooth whitening treatment ( n = 10 ) : 6.0 % hydrogen peroxide ( HP ) ( Crest Whitestrips ) , 6.5 % HP ( Crest Professional Whitestrips ) , 7.5 % HP ( Day White Excel 3 ) , 9.5 % HP ( Day White Excel 3 ) , 10 % carbamide peroxide ( Opalescence ) , and a control group ( untreated ) . Specimens were treated for 14 days following manufacturers ' recommended protocol s , and were immersed in artificial saliva between treatments . Enamel surface Knoop microhardness ( KHN ) was measured immediately before treatment , and at days 1 , 7 , and 14 of treatment . After treatment , subsurface microhardness was measured at depths of 50 - 500 microm . Data were analyzed for statistical significance using analysis of variance . RESULTS Differences in microhardness for treated vs. untreated enamel surface were not statistically significant at any time interval . For 6.5 % and 9.5 % HP , there was a decrease in surface microhardness values during treatment , but at the end of treatment the microhardness values were not statistically different from the baseline values . For the enamel subsurface values , no differences were observed between treated vs. untreated specimens at each depth . Trayless and tray-based tooth whitening treatments do not significantly affect surface or subsurface enamel microhardness
The results of this meta- analysis showed no significant changes in enamel microhardness when using the 10 % carbamide peroxide bleaching gel over periods of 7 , 14 and 21 days
Several studies have investigated the effect of bleaching on dental tissues .
The evaluation of the effect of home bleaching with 10 % carbamide peroxide is important for assessing alterations in enamel microhardness that may affect dental health in terms of resistance to masticatory forces .
This meta- analysis was performed in order to determine scientific evidence regarding the effects of home vital bleaching with 10 % carbamide peroxide gel on the microhardness of human dental enamel .