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Brazilian Journal of Oral Sciences
Piracicaba Dental School - UNICAMP
EISSN: 1677-3225
Vol. 14, No. 4, 2015, pp. 262-266
Bioline Code: os15047
Full paper language: English
Document type: Research Article
Document available free of charge

Brazilian Journal of Oral Sciences, Vol. 14, No. 4, 2015, pp. 262-266

 en Effect of bleaching agents containing fluoride or calcium on enamel microhardness, roughness and permeability
Rauen, Charles Alex; Filho, Júlio Cezar Chidoski; Bittencourt, Bruna Fortes; Gomes, Giovana Mongruel; Gomes, João Carlos & Gomes, Osnara Maria Mongruel


Aim: To evaluate the effect of different in-office bleaching agents on the permeability, roughness and surface microhardness of human enamel.
Methods: For evaluation of roughness and microhardness, 40 hemi-faces of 20 premolars were subjected to initial roughness (Ra parameter) and microhardness (VHN) measurements. Thirty-two premolar’s crowns were used for permeability test. Then, all specimens were randomly divided into four groups: C - without bleaching (control), HP35 - bleaching with 35% hydrogen peroxide (HP), HPF38 - 38% HP+fluoride, HPC35 - 35% HP+calcium. Final roughness (FR) and microhardness (FM) measurements were evaluated. For permeability, the 32 crowns were immersed in 1% sodium hypochlorite (20 min) and silver nitrate solutions (2 h) and subjected to developing solution under fluorescent light (16 h). Three sections from the crowns were analyzed in light microscope (100x) to evaluate the scores of permeability: Score 0 - no tracer agent penetration; Score 1 - less than half the thickness of enamel penetration; Score 2 - tracer agent reaching half the enamel thickness; Score 3 - entire enamel depth penetration, without reaching dentin and Score 4 - tracer agent reaching dentin. For roughness and microhardness evaluation were used one-way ANOVA and Dunnet post-test for independent samples, and t test for paired samples. For permeability, the data were analyzed by Kruskal Wallis and Dunn tests.
Results: A significantly higher permeability and surface roughness were observed in groups HP35, HPF38 and HPC35 compared to the C group, as well as decreased microhardness (p<0.05).
Conclusions: All bleaching agents increased permeability and surface roughness, and decreased microhardness of human enamel; thus, the addition of fluoride or calcium was not beneficial.

tooth bleaching; dental enamel permeability; hydrogen peroxide; surface properties

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