Influence of fluoride concentration and pH Value of 35% hydrogen peroxide on the hardness, roughness and morphology of bovine enamel

The aim of this in vitro study was to evaluate the effects of different sodium fuoride (NaF) concentrations and pH values on the Knoop hardness (KHN), surface roughness (SR), and morphology of bovine incisors bleached with 35% hydrogen peroxide (HP). Sixty-five bovine incisors were fragmented (5 mm(...

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Bibliographic Details
Published in:	The journal of contemporary dental practice Vol. 15; no. 4; pp. 392 - 398
Main Authors:	Nascimento, Wilcilene Costa, Gomes, Yasmin do Socorro Batista de Lima, Alexandrino, Larissa Dias, Costi, Hilton Tulio, Silva, Jr, Josá Otévio Carrera, Silva, Cecy Martins
Format:	Journal Article
Language:	English
Published:	India 01-07-2014
Subjects:	Animals Cariostatic Agents - analysis Cariostatic Agents - pharmacology Cattle Dental Enamel - drug effects Dental Enamel - ultrastructure Dentistry Hardness Hydrogen Peroxide - pharmacology Hydrogen-Ion Concentration Materials Testing Microscopy, Electron, Scanning Sodium Fluoride - analysis Sodium Fluoride - pharmacology Tooth Bleaching Agents - analysis Tooth Bleaching Agents - pharmacology
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Summary:	The aim of this in vitro study was to evaluate the effects of different sodium fuoride (NaF) concentrations and pH values on the Knoop hardness (KHN), surface roughness (SR), and morphology of bovine incisors bleached with 35% hydrogen peroxide (HP). Sixty-five bovine incisors were fragmented (5 mm(2) × 2 mm) and distributed in 5 groups: Control (unbleached), Low NaF/Acidic (35% HP + 1.3% NaF, pH 5.5), Low NaF/Neutral (35% HP + 1.3% NaF, pH 7.0), High NaF/ Acidic (35% HP + 2% NaF, pH 5.5), and High NaF/Neutral (35% HP + 2% NaF, pH 7.0). KHN analysis was performed with a microhardness tester under a load of 25 gf for 5 seconds. The average SR was obtained with a rugosimeter. KHN and SR were analyzed before and after treatments. For morphological analysis, specimens were dehydrated and gold-sputtered, and scanning electron micrographs were obtained and analyzed by 3 examiners with a double-blinded technique. KHN and SR results were analyzed by one-way ANOVA and Tukey's test (p < 0.05). Only the Low NaF/Acidic and Low NaF/Neutral groups showed significant differences between the initial and final KHN values. All bleached groups presented significant differences between the initial and final SR values. Among the bleached groups, the least and most morphological changes were shown by the High NaF/Neutral and the Low NaF/Acidic group, respectively. Treatment with 35% HP and 2% NaF at pH 7.0 promoted the least changes in morphology, hardness and roughness among the bleached groups. In-office bleaching with high-concentration HP and 2% NaF at neutral pH promoted the least changes in enamel hardness, SR, and morphology compared to other treatments.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1526-3711 1526-3711
DOI:	10.5005/jp-journals-10024-1550