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Results for “Carbamide Peroxide”

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At least 19 recordsLinked to original sources
PubMed1992

The effect of carbamide-peroxide gel on the shear bond strength of a microfil resin to bovine enamel.

Cylinders of a visible-light-cured microfil resin were formed on, and bonded to, the flattened labial enamel surfaces of young bovine incisor teeth which had previously been subjected to four different treatments: (1) immersion in 10% carbamide-peroxide gel, pH 4.7, for three h; (2) immersion in 10% carbamide-peroxide gel, pH 4.7, for six h; (3) immersion in 10% carbamide-peroxide gel, pH 7.2, for three h; and (4) immersion in 10% carbamide-peroxide gel, pH 7.2, for six h. For each experimental group, a control group of resin-bonded to saline-immersed teeth was prepared. In addition, two groups, prepared according to treatment 4, were leached in distilled water for one and seven d, respectively, prior to resin application. Specimens were stored in distilled water at 37 degrees C for seven d prior to shear-bond-strength testing. A total of 90 teeth was tested. Statistical analysis of the results indicated that there was a highly significant reduction in the shear bond strength to carbamide-peroxide-treated enamel as compared with that to saline-treated enamel. The effects of duration of peroxide treatment and pH, as well as the interaction term, were not statistically significant. Leaching of the peroxide-treated enamel in water for either one or seven d prior to resin application restored the adhesiveness of the enamel. Scanning electron microscopic examination of randomly selected, fractured test specimens indicated that the peroxide-induced reduction in enamel adhesiveness was related to alterations in both attachment-surface area at the resin-enamel interface and resin quality.

Analysis of Variance↗
PubMedDate not supplied

Carbamide peroxide bleaching: effects on enamel surface hardness and bonding.

Three 10% carbamide peroxide home bleaching agents were evaluated to determine their effects on tensile bond strength of resin to enamel and enamel surface hardness. Eighty extracted bicuspid crowns were divided into four groups (three bleaching agents and control), and treated with the bleaching agents for five consecutive days. A bonding site on the buccal surface of each crown was etched with phosphoric acid and an orthodontic bracket bonded in place. The specimens were thermocycled and loaded to failure in an Instron Universal Testing Machine. Five hardness specimens per group were measured prebleaching and after five days' exposure. Analysis by one-way ANOVA indicated no significant differences in bond strength between the four groups (P > 0.05). There were also no differences in pre- or postbleaching Knoop hardness values for the four groups (P > 0.05). This study indicated that in short-term regimens 10% carbamide peroxide does not significantly affect enamel surface hardness or bonding ability.

Analysis of Variance↗
PubMed1992

Penetration of the pulp chamber by carbamide peroxide bleaching agents.

Hydrogen peroxide readily penetrates the pulp chamber of freshly extracted teeth. This study was undertaken to determine whether carbamide peroxide also penetrates the pulp chamber. Freshly extracted teeth were sectioned 2 to 3 mm apical to the cementoenamel junction and the coronal pulpal tissue was removed. Acetate buffer was placed in the pulp chamber to absorb and stabilize any peroxide that might penetrate. The coronal portion of each tooth was immersed in either carbamide peroxide gel or gelled hydrogen peroxide at various concentrations for 15 min at 37 degrees C. The buffer was removed, leukocrystal violet was added, and the optical density of the resulting blue solution was determined spectrophotometrically. Amounts of peroxide found in the pulp chamber after 15 min ranged from 3.3 +/- 0.38 micrograms for the 10% sample to 40.4 +/- 3.51 micrograms for the 30% sample.

Carbamide Peroxide↗
PubMedDate not supplied

Bond strength of composite resin to enamel bleached with carbamide peroxide.

Bleaching with 35 percent hydrogen peroxide causes enamel surface changes, which result in lower bond strengths of composite resin. Although a previous SEM study showed that home bleaching with 10 percent carbamide peroxide does not cause such surface changes, the results of our study indicate that carbamide peroxide bleaching reduces the shear bond strength of composite to etched enamel. Removal of surface enamel, however, restores bond strengths to normal levels.

Acid Etching, Dental↗
PubMed1992

Carbamide peroxide at-home bleaching agents. An update.

Interest in the use of bleaching for treatment of discolored teeth is increasing. Bleaching, especially at-home mouthguard bleaching, is considered by many professionals to be the most conservative, non-invasive treatment modality currently available.

Carbamide Peroxide↗
PubMedDate not supplied

Double-blind whitening Night-Guard study using ten percent carbamide peroxide.

The conservative technique of professionally dispensed and supervised, home-administered vital bleaching is now a routine treatment in the dental profession. This double-blind study evaluated the Rembrandt Lightening Gel and Whitening Toothpaste for shade change, colorimeter shade change. As well, it evaluated soft tissue health by periodontal probing, plaque index, and bleeding index. A patient questionnaire evaluated perception of whitening, perception of oral hygiene, average hours per day, and average days per week. Bleaching trays were worn over a 4-week period. The bleaching system showed definitive whitening effects as evaluated with the Vita shade guide and the colorimeter. The bleaching system had no deleterious effects on the soft tissue. The Rembrandt toothpaste alone demonstrated two-shade lightening. This vital bleaching system shows definitive whitening of the teeth in short periods of time with no adverse effects.

Carbamide Peroxide↗
PubMed1991

The safety and efficacy of tooth bleaching: a review of the literature 1988-1990.

Two hundred fifty-six major medical and dental journals were searched, and a comprehensive study was completed on the chemistry of hydrogen peroxide and carbamide peroxide. The results indicate that safety and efficacy of hydrogen peroxide is well established, while carbamide peroxide is much more complicated and no long-term safety studies are available for tooth bleaching using carbamide peroxide.

Carbamide Peroxide↗
PubMedDate not supplied

Is home tooth bleaching gel cytotoxic?

Tooth whitening systems are widely used clinically and for home usage. The aim of this study was to determine the effects of two bleaching gels, each containing 10 percent and 15 percent carbamide peroxide, respectively, a 'bleaching gel' without carbamide peroxide, and carbamide peroxide alone on the viability of human endothelial cells in vitro in comparison with culture medium that acted as a negative control. The incubation period used was 30 minutes. A colorimetric viability assay (MTT assay) was employed. The results showed that the gel without carbamide peroxide is not cytotoxic compared to the negative control, while carbamide peroxide on its own and 10 percent and 15 percent carbamide peroxide bleaching gels were cytotoxic, but there were no significant differences (p greater than 0.05) among these latter three test groups. These data indicate that 10 percent and 15 percent carbamide peroxide bleaching gels are cytotoxic and that carbamide peroxide is the component responsible for this cytotoxic effect. This paper also discusses why this in vitro cytotoxic effect appears not to be significant in vivo.

Analysis of Variance↗
PubMed1992

Catalase/peroxidase activity in dental pulp.

Extrinsic stains on vital teeth are bleached with 30% hydrogen peroxide (H2O2) or carbamide peroxide, H2O2 greatly inhibits the activity of several enzymes. Free H2O2 and carbamide peroxide readily enter the pulp through the coronal wall of the tooth. Nevertheless, adverse effects have been remarkably rare. This study was undertaken to determine whether dental pulp exhibits any catalase or peroxidase activity that might protect it from damage during vital bleaching procedures. Pulpal tissue from healthy human teeth was assayed for catalase and glutathione peroxidase activity. A phosphate buffer extract of the tissue served as the source of the enzymes. The rate of breakdown of H2O2 by the tissue extract was measured and the rate constant for catalase was determined. The catalase activity, defined as microM H2O2 broken down/min/mg wet tissue, was determined and found to be only 2 x 10(-2), which is very low. The fibrous pulpal tissue was found to exhibit virtually no glutathione peroxidase activity.

Catalase↗
PubMed1992

Effect of peroxide bleaches on resin-enamel bonds.

Human third molar teeth were divided into three groups: untreated control; enamel treated with 35% hydrogen peroxide for 2 hours; and enamel treated with 10% carbamide peroxide gel for 14 days. All teeth were ground to present a flat enamel surface, to which cylinders of light-cured composite resin were bonded. Shear bond strengths were determined for each specimen. The mean shear bond strengths of resin-enamel bonds after pretreatment with both 35% hydrogen peroxide and 10% carbamide peroxide were significantly lower than those for untreated controls. External bleaching with these materials prior to resin bonding procedures may reduce the quality of resin-enamel bonds.

Acrylates↗
PubMed1991

Nightguard vital bleaching: how safe is it?

The conservative technique for bleaching vital teeth using a nightguard and a 10% carbamide peroxide solution has captured the esthetic interests of the dental profession. The purpose of this article is to assess the safety of the products used in this bleaching technique based on results from past related research and current research. Ten percent carbamide peroxide solutions used in numerous studies have demonstrated tissue-healing properties as well as a propensity for the reduction of plaque and gingivitis. None of these clinical studies revealed any untoward or detrimental side effects, and all demonstrated beneficial effects. Although some concern exists regarding the potentiating effects of peroxide solutions in the presence of known carcinogens, concerns of toxicity or damage to hard and soft tissues appear unfounded. The majority of current and past research and literature indicates that the current use of a 10% carbamide peroxide solution in the method advocated for bleaching vital teeth is apparently safe when administered properly under the supervision of a dentist.

Carbamide Peroxide↗
PubMed1992

Post-operative bleaching: effect on microleakage.

The effect of a carbamide peroxide bleaching gel on the microleakage of Class V resin composite restorations with two dentin bonding agents was evaluated using extracted human teeth. Class V cavity preparations were placed at the cementoenamel junction of the facial and lingual surfaces of 20 teeth for a total of 40 preparations. Half of the teeth were restored with Scotchbond 2/Silux Plus and half were restored with Prisma Universal Bond 3/AP.H. Five teeth were randomly selected from each of the two groups and were stored in water at 37 degrees C to serve as controls. The remaining teeth were exposed to a carbamide peroxide gel for three 2-hour periods per day for 9 days. The specimens were stored in distilled water at 37 degrees C except during treatment periods. All teeth were then thermally stressed for 100 cycles. Microleakage was assessed by dye penetration. The results demonstrated that the carbamide peroxide agent adversely affected the marginal seal of both restorative systems.

Carbamide Peroxide↗
PubMed1990

Nightguard vital bleaching: effects on enamel surface texture and diffusion.

A recently reported technique for bleaching vital discolored teeth involves the use of a mouthguard and 10% carbamide peroxide without preoperative etching or postoperative polishing of the enamel. This in vitro study evaluated the effects of the bleaching agent on the surface texture of the enamel. Thirty-three extracted teeth were subjected to 10% carbamide peroxide for a period equivalent to 5 weeks of nighttime wear. A control area on each tooth had been covered and sealed. All discolored teeth experienced lightening, but there was no difference in color between the treated and control areas; the color-changing effects apparently extend to portions of the tooth not in direct contact with the solution. Epoxy replicas of the teeth were examined under a scanning electron microscope. No etching was apparent, and no difference in surface texture between treated and control areas was detected.

Bicuspid↗
PubMedDate not supplied

Overview and status of mouthguard bleaching.

Since the bleaching of vital teeth using a tray delivery system with a 10 percent carbamide peroxide first became common knowledge in March, 1989, there has been much discussion, improvement, and questions concerning the process and the various products available. This article presents an overview of its history, the variations in techniques, and questions concerning safety, including the impact on tooth structure, the pulp, soft tissue of the mouth, and systemic ingestion. It divides currently available products according to their composition, into either a carbamide peroxide with and without carbopol, a hydrogen peroxide of varying concentrations, a hydrochloric acid, or other categories. It discusses the various delivery mechanisms and comments on their apparent effectiveness, as well as reflecting the current knowledge base of the profession.

Carbamide Peroxide↗
PubMed1992

Enamel microabrasion followed by dental bleaching: case reports.

Certain enamel coloration defects can best be eliminated by a combination of treatment methods. This report describes the treatment of two patients whose enamel discoloration was corrected with a combination of enamel microabrasion and patient-administered dental bleaching with a carbamide peroxide gel solution.

Adolescent↗
PubMed1992

Effects of home bleaching preparations on composite resin color.

The lightening of teeth is done professionally by exposure to warm hydrogen peroxide solutions or at home with an active bleaching gel of perhydrol urea or carbamide peroxide. This study compared the effects of two commercial bleaching gels on the color of composite resin with those in a previous study using the dental office technique. Commercial composite resins test specimens were exposed to the bleaching gels or water (control) for 312 hours at 37 degrees C at 100% relative humidity. Color change value was calculated with before-and-after solution exposure L*a*b* color values. ANOVA (alpha = 0.01) revealed no differences in the color of the specimens after use of the test solutions. All color change values were less than 2 or the normal limit of visual acuity. No visual color change was evident for these composite resins. The at-home method recorded no shade-altering effects compared with the professional technique, which created a noticeable color change.

Analysis of Variance↗
PubMed1992

Alterations in human enamel surface morphology following vital bleaching.

Extracted intact human teeth (n = 4) were treated for 30 days by three protocols: Home 1 (Proxigel, n = 4) for 8 hours daily, Home 2 (White & Bright, n = 4) for 24 hours with 3 minutes of stannous fluoride gel, or an Office protocol (n = 4) using 30% hydrogen peroxide (Superoxol) warmed by a high-intensity light while the controls remained untreated. "Home" bleaching agents contain approximately 10% carbamide peroxide. After treatment, the coronal surfaces were examined with a scanning electron microscope (SEM) at 2000 power magnification, and the surface topography was measured by a profilometer. The SEM photomicrographs of the controls and office-treated groups were similar to previously reported descriptions, while the home bleached surfaces appeared similar to each other. Profilometric analysis was used to examine surface roughness and surface waviness. Mean surface roughness in microns was: control, 1.9; Home 1, 0.6; Home 2, 0.9; and Office, 0.6. Surface waviness was ranked control > office > Home 1 = Home 2. Enamel surface alterations were evident after the three bleaching methods. The differences between the office and home-treated surfaces were unrelated to the pH of the bleaching agents.

Carbamide Peroxide↗