Mineral loss and morphological changes in dental enamel induced by a 16% carbamide peroxide bleaching gel.
The aim of this study was to compare the effect of a 16% carbamide peroxide (CP) gel and a 10% CP gel on mineralized enamel content and morphology. Enamel blocks from bovine incisors were subjected to a 14-day treatment (8 h/day) with 10% or 16% CP gels. Knoop microhardness was evaluated before bleaching and at 1, 7 or 14 days after this treatment (50 g/15 s). Mineral content (energy-dispersive x-ray spectroscopy), surface roughness and topography (atomic force microscopy) were evaluated at the 14-day period. Data were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). Significant microhardness reduction was observed at the 7 th and 14 th days for 10% CP gel, and for all bleaching times for 16% CP gel (p<0.05). At the 14-day period, a significant decrease in Ca and P content, increase on surface roughness (p<0.05) as well as on picks and valleys distance were observed when both bleaching gels were used. These enamel alterations were more intense for 16% CP gel. It was concluded that both CP-based gels promoted loss of mineral structure from enamel, resulting in a rough and porous surface. However, 16% CP gel caused the most intense adverse effects on enamel.
Department of Dental Materials and Prosthodontics, Araraquara School of Dentistry, UNESP - Univ Estadual Paulista, AraraquaraSP, Brazil.
Diana Gabriela
DG
Soares
Department of Dentistry, School of Dentistry, UNIB - University of Brasília, BrasíliaDF, Brazil.
Ana Paula Dias
AP
Ribeiro
Department of Stomatological Sciences, School of Dentistry, UFG - Federal University of Goiás, GoiâniaGO, Brazil.
Nancy Tomoko
NT
Sacono
Department of Restorative Dentistry, School of Dentistry, UEPG - State University of Ponta Grossa, Ponta GrossaPR, Brazil.
Alessandro Dourado
AD
Loguércio
Department of Pediatric Dentistry and Orthodontics, Araraquara School of Dentistry, UNESP - Univ Estadual Paulista, AraraquaraSP, Brazil.
Josimeri
J
Hebling
Department of Physiology and Pathology, Araraquara School of Dentistry, UNESP - Univ Estadual Paulista, AraraquaraSP, Brazil.
Carlos Alberto de Souza
CA
Costa
D000077463:Carbamide Peroxide; D003743:Dental Enamel / Q000187:drug effects*; D005782:Gels; D006245:Hardness Tests; D006801:Humans; D018625:Microscopy, Atomic Force; D010545:Peroxides / Q000008:administration & dosage / Q000009:adverse effects*; D013052:Spectrometry, X-Ray Emission; D014073:Tooth Bleaching / Q000379:methods*; D017001:Tooth Demineralization / Q000139:chemically induced*; D014508:Urea / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*
D005782:Gels; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea