Home About us Contact
|
Home About us Contact | ||
|
|
||
Hydrogen Peroxide Solution (hydrogen + peroxide_solution)
Selected AbstractsSealing capacity of a photochromatic flowable composite as protective base in nonvital dental bleachingINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2006C. Llena Abstract Aim, To evaluate microleakage of a flowable composite used as a protective isolating base, applied with different adhesive systems. Methodology, Seventy root-filled teeth were divided into seven groups. A flowable composite base (Tetric Flow Chroma) was used with three adhesive techniques (Syntac, Excite, Excite DCS; in the three cases with and without acid etching) and in a control group without dentine conditioning or adhesive placement. A 30% hydrogen peroxide solution was applied for 24 h in the pulp chambers, followed by the placement of a dye (silver nitrate) for 4 h. Each tooth was sectioned longitudinally, and examined under 4× magnification to assess the tooth/restoration dye leakage following a four-degree scale. Percentage of dye penetration was registered. Statistical analysis was made through the Tukey and Mann,Whitney U -tests. Results, Maximum leakage (100% of specimens) was recorded in the control group without an adhesive system. In the groups subjected to acid etching, the percentage of leakage corresponded to Excite DSC (10%), followed by Syntac (20%) and Excite (30%). In the groups in which only an adhesive system was used, 50% of the teeth demonstrated dye leakage. Statistically significant differences in terms of leakage were observed between the control group and the experimental groups (P < 0.05). There were no significant differences among the experimental groups, but comparing the leakage percentages obtained between the groups in which the teeth were subjected to prior acid etching, and those in which no etching was carried out, observed differences were significant (P = 0.04). Conclusions, There were no significant differences between the adhesive systems in terms of leakage. Acid etching significantly reduced leakage. [source] Measurement of stain on extracted teeth using spectrophotometry and digital image analysisINTERNATIONAL JOURNAL OF DENTAL HYGIENE, Issue 3 2007DL Lath Abstract:, Aim:, The aim of this study was to assess the reliability and validate a customized image analysis system, designed for use within clinical trials of general dental hygiene and whitening products, for the measurement of stain levels on extracted teeth and to compare it with reflectance spectrophotometry. Method:, Twenty non-carious extracted teeth were soaked in an artificial saliva, brushed for 1 min using an electric toothbrush and a standard toothpaste, bleached using a 5.3% hydrogen peroxide solution and cycled for 6 h daily through a tea solution. CIE L* values were obtained after each treatment step using the customized image analysis system and a reflectance spectrophotometer. A statistical analysis was carried out in SPSS. Results:, Fleiss' coefficient of reliability for intra-operator repeatability of the image analysis system and spectrophotometry was 0.996 and 0.946 respectively. CIE L* values were consistently higher using the image analysis compared with spectrophotometry, and t -tests for each treatment step showed significant differences (P < 0.05) for the two methods. Limits of agreement between the methods were ,27.95 to +2.07, with a 95% confidence of the difference calculated as ,14.26 to ,11.84. The combined results for all treatment steps showed a significant difference between the methods for the CIE L* values (P < 0.05). Conclusion:, The image analysis system has proven to be a reliable method for assessment of changes in stain level on extracted teeth. The method has been validated against reflectance spectrophotometry. This method may be used for pilot in vitro studies/trials of oral hygiene and whitening products, before expensive in vivo tests are carried out. [source] Enamel Microabrasion: A New ApproachJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2000THEODORE P. CROLL DDS ABSTRACT Enamel microabrasion is a proven method of removing superficial intrinsic enamel discoloration defects. The method is safe, easily performed, and causes no discomfort for the patient. A new commercially available microabrasion system has been introduced by Ultradent Products Inc. In addition, a new tooth isolation material is available, along with a visible light-activated in-office hydrogen peroxide solution. This article describes these new products and documents tooth-color correction for two young patients using this new tooth-color correction approach. CLINICAL SIGNIFICANCE Enamel microabrasion and vital bleaching can be used effectively to treat enamel dysmineralization and associated discoloration in children and adolescents. [source] Effect of traditional and alternative intracoronal bleaching agents on microhardness of human dentineJOURNAL OF ORAL REHABILITATION, Issue 8 2004H. K. Chng summary, The purpose of this study was to compare the effect of traditional and alternative bleaching agents on microhardness of human dentine when used intracoronally. Thirty-six premolars were divided into six groups and bleaching agents were sealed into the pulp chambers as follows: group 1 , distilled water (control), group 2,30% hydrogen peroxide solution, group 3 , sodium perborate mixed with distilled water, group 4 , sodium perborate mixed with 30% hydrogen peroxide solution, group 5,35% carbamide peroxide gel, group 6,35% hydrogen peroxide gel. Access cavities were sealed and the teeth were stored in distilled water at 37°C. After 7 days, each tooth was sectioned at the cemento-enamel junction level and microhardness testing was carried out on dentine. The results showed that treatment with 35% hydrogen peroxide gel, 30% hydrogen peroxide solution and 35% carbamide peroxide gel reduced the microhardness of outer dentine to a small extent while treatment with sodium perborate mixed with water and sodium perborate mixed with 30% hydrogen peroxide solution did not significantly alter the microhardness of dentine. [source] Tetrabromohydroquinone and riboflavin are possibly responsible for green luminescence in the luminous acorn worm, Ptychodera flavaLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2005Akira Kanakubo Abstract 2,3,5,6-Tetrabromohydroquinone was isolated as a luminous substance from Ptychodera flava. This compound emitted light after addition of hydrogen peroxide under basic conditions. Since hydroquinone had no fluorescence, further investigation by spectral analysis revealed that riboflavin was the only possible light emitter having green fluorescence. In the presence of both tetrabromohydroquinone and riboflavin under a basic condition containing 70% 1,4-dioxane, green light emission was observed following the addition of hydrogen peroxide. We succeeded in recording the same emission spectrum as that in the bioluminescence caused by the addition of aqueous diluted hydrogen peroxide solution in P. flava. Copyright © 2005 John Wiley & Sons, Ltd. [source] Aqueous photolysis of 8:2 fluorotelomer alcoholENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2005Suzanne A. Gauthier Abstract The 8:2 fluorotelomer alcohol (8:2 FTOH) was photodegraded in aqueous hydrogen peroxide solutions, synthetic field water (SFW) systems, and Lake Ontario (Canada) water samples. It was found to undergo indirect photolysis, with the data suggesting that the hydroxyl radical was the main degradation agent and that nitrate promoted photolysis whereas dissolved organic carbon inhibited it. The half-lives of 8:2 FTOH were 0.83 ± 0.20 h (10 mM H2O2), 38.0 ± 6.0 h (100 ,M H2O2), 30.5 ± 8.0 to 163.1 ± 3.0 h (SFW systems), and 93.2 ± 10.0 h (Lake Ontario). No significant loss of the parent compound by direct photolysis could be observed. The major monitored products were the 8:2 fluorotelomer aldehyde, the 8:2 fluorotelomer acid (8:2 FTCA), and perfluorooctanoate (PFOA); the minor monitored products were the 8:2 fluorotelomer unsaturated acid (8:2 FTUCA) and perfluorononanoate (PFNA). The intermediates, 8:2 FTCA and 8:2 FTUCA, were photodegraded to verify the degradation pathway, and a mechanism for the photolysis was proposed whereby the end products of the photolysis pathway were PFOA (major) and PFNA (minor). [source] Low-Temperature Growth of Monolayer Rutile TiO2 Nanorod FilmsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2007Jin-Ming Wu Low-temperature growth of well-crystallized titania thin films with controlled nanofeatures are of great interest because of their potential uses in catalysts, gas sensors, photovoltaic cells, photonic crystals, etc. This paper reports the synthesis of a well-crystallized, pure rutile monolayer consisting of well-aligned nanorods with average diameters of ca. 25 nm and an aspect ratio of ca. 6 through a simple solution approach at a low temperature of 80°C. The monolayer nanorods precipitate from the precursors that were obtained through the reaction between metallic titanium and hydrogen peroxide solutions at 80°C for 24,60 h. The nanoporous titania thin layer derived by oxidizing the titanium substrate with hydrogen peroxide at 80°C for 10 min facilitates the growth of the monolayer rutile TiO2 nanorod films. [source] | ||||||||||