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J. appl. oral sci ; 26: e20170589, 2018. tab, graf
Artículo en Inglés | LILACS, BBO | ID: biblio-954496

RESUMEN

Abstract High concentrations of hydrogen peroxide can cause adverse effects on composition and structure of teeth. However, the addition of calcium and fluoride in bleaching agents may reduce enamel demineralization. Objective: To evaluate chemical changes of sound and demineralized enamels submitted to high concentrations of hydrogen peroxide containing fluoride (F) or calcium (Ca). Material and Methods: Enamel blocks of bovine incisors with standard dimensions were obtained and half of them were submitted to pH-cycling to promote initial enamel caries lesions. Sound and demineralized enamel samples were divided into (n=10): (C) Control (no whitening treatment); (HP) 35% hydrogen peroxide; and two experimental groups: (HPF) 35% HP+0.2% F and (HPC) 35% HP+0.2% Ca. Experimental groups were submitted to two in-office bleaching sessions and agents were applied 3 times for 15 min to each session. The control group was kept in remineralizing solution at 37°C during the bleaching treatment. The surface mineral content of sound and demineralized enamels was determined through Fourier Transform Raman spectroscopy (FT-Raman), Energy dispersive Micro X-ray fluorescence spectroscopy (μ-EDXRF); and the subsurface, through cross-sectional microhardness (CSMH). In addition, polarized light microscopy (PLM) images of enamel subsurface were observed. Results: According to three-way (FT-Raman and μ-EDXRF analyses) or two-way analysis of variance (ANOVA) (CSMH) and Tukey test (α=5%), the calcium or fluoride added to high-concentrated bleaching agents increased phosphate and carbonate concentrations on sound and demineralized enamels (p<0.05). However, HPC and HPF were unable to completely reverse the subsurface mineral loss promoted by bleaching on sound and demineralized enamels. The calcium/ phosphate (Ca/P) ratio of sound enamel decreased after HP treatment (p<0.001). Conclusion: Even though experimental bleaching agents with Ca or F reduced mineral loss for both sound and demineralized enamel surfaces, these agents were unable to reverse the enamel subsurface demineralization.


Asunto(s)
Animales , Bovinos , Calcio/química , Desmineralización Dental/inducido químicamente , Esmalte Dental/efectos de los fármacos , Blanqueadores Dentales/química , Fluoruros/química , Peróxido de Hidrógeno/química , Fosfatos/química , Valores de Referencia , Espectrometría por Rayos X , Espectrometría Raman , Propiedades de Superficie/efectos de los fármacos , Factores de Tiempo , Blanqueamiento de Dientes/efectos adversos , Blanqueamiento de Dientes/métodos , Ensayo de Materiales , Carbonatos/química , Reproducibilidad de los Resultados , Esmalte Dental/química , Blanqueadores Dentales/efectos adversos , Pruebas de Dureza , Microscopía de Polarización
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