Influence of Remineralizing Gels on Bleached Enamel Microhardness In Different Time Intervals

Abstract

©Operative Dentistry, 2010, 35-2, 180-186 Clinical RelevanceDentists should be aware of the reduction in enamel microhardness after bleaching procedures. The use of remineralizing gels after bleaching treatment can significantly enhance bleached enamel microhardness. AB Borges • KCK Yui • TC D'Avila CL Takahashi • CRG Torres • ALS Borges SUMMARYThis study evaluated the influence of bleaching gel pH, the effect of applying remineralizing gels after bleaching and the effect of artificial saliva on enamel microhardness. Seventy bovine incisors were divided into three groups: Group 1 (n=10) received no bleaching procedure (control); Group 2 was bleached with a 35% hydrogen peroxide neutral gel (n=30) and Group 3 was bleached with a 35% hydrogen peroxide acid gel (n=30). Each experimental group was subdivided into three groups (n=10) according to the postbleaching treatment: storage in artificial saliva, application of a fluoride gel and application of a combination of calcium and fluoride gel. The specimens were stored in artificial saliva for 7, 15 and 30 days and enamel microhardness was evaluated. The Vickers microhardness data were analyzed by three-way RM ANOVA, which revealed a significant difference only for treatment factor. The Tukey's test showed that the groups bleached followed by no additional treatment exhibited microhardness means significantly lower than the bleached groups treated with remineralizing gels. The Dunnet's test showed a significant difference only for the group bleached with acid gel without remineralizing treatment compared to the control group measured immediately after bleaching. It was concluded that acid bleaching gel significantly reduced enamel microhardness and that use of remineralizing gels after bleaching can significantly enhance the microhardness of bleached enamel.

Will Resin Infiltration With Icon Prevent Enamel Demineralization Around Orthodontic Brackets?

“…Regarding surface micro-hardness,Vickers hardness values for sound enamel were used as reported in previous studies 15,16 .The results showed that after pH cycling there was no statistically significant difference in micro-hardness between the ICON surface pretreatment and the control groups which was in accordance with Burgess and Cakir 17 , and Mugisa 18 . Nadia et al in 2012 19 reported that ICON surface pretreatment sealed the enamel porosities in the infiltrated enamel and, hence the resulted absence of an increase in the surface hardness compared to sound enamel.…”

Clinical Effects of Prolonged Application Time of an In-office Bleaching Gel

“…Recently, Borges and others 33 evaluated the influence of two bleaching gels with different pH (acid 3.5 and neutral 6.6) on enamel microhardness. The authors concluded that the enamel microhardness decreased significantly when the most acidic bleaching agent was compared with the neutral formulation.…”

Effect of different storage conditions on the physical properties of bleached enamel: An in vitro vs. in situ study

“…However, the samples maintained in the other storage media showed no decrease in hardness at the same time analyses. A reduction in hardness after bleaching has been reported in other studies 5,8,9,13,24 and has often been associated with demineralization of the surface by the action of bleaching agents, probably due to its low pH and its oxidative power. 4 In this present study, a change in hardness was observed only in PW.…”

“…However, other studies that used artificial saliva as the storage medium were unable to reverse the demineralization effect. 3,9,10,24,27,28 This might have been caused by a lack of standardization in artificial saliva formulations, since different types of saliva may result in higher or lower remineralization. This lack of standardization impairs the comparison and application of various study results.…”