Effect of Different Topical Fluorides on the Microhardness of Bleached Enamel: In Vitro Study

Esthetic dentistry plays an important role in providing several treatment options for tooth discoloration out of which the most common is tooth bleaching. Although it is less invasive and cost-effective but repeated bleaching could reduce the microhardness of enamel; this loss of microhardness after bleaching could be regained by incorporating topical fluoride agents.

To analyze and compare the effect of fluoride and additional fluoride application on the microhardness of the enamel prior to and postbleaching.

Fifty sound extracted human premolars were divided into five groups and subjected to specific fluoride treatment pre- and postbleach period for 42 days. Microhardness of each specimen was recorded at baseline, 14th, 28th, and 42nd day.

An intergroup comparison of each enamel specimen at different timelines was done by analysis of variance (ANOVA) test. Intragroup comparison at baseline was done using a post hoc test, and at 14th, 28th, and 42nd day was done by Bonferroni correction. The F-and p-value for baseline were 1.718 and 0.163, respectively, which were not significant. While F-value at 14th, 28th, and 42nd day was 33.036, 5.395, and 9.505, respectively, which shows all these timelines had a p-value <0.001 and the difference was statistically significant. A statistically significant increase was observed between specimens treated with combined fluoride therapy and only fluoridated toothpaste application at the end of 14th day, and no statistically significant difference was there at the end of 42nd day.

A significant increase in the microhardness of bleached enamel on fluoridated toothpaste application was observed. Further additional application of fluoride was not very effective when fluoridated toothpaste was used twice daily.

Das S, Jain M, Sogi HPS, et al. Effect of Different Topical Fluorides on the Microhardness of Bleached Enamel: In Vitro Study. Int J Clin Pediatr Dent 2025;18(11):1365-1372.