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PubMed2006

The effect of 16 percent carbamide peroxide on enamel staining susceptibility.

STATEMENT OF PROBLEM: Recently, vital bleaching by carbamide peroxide has become more popular; therefore, it is necessary to study the effect of this agent on enamel and dentin. PURPOSE: The purpose of this study was to evaluate the effect of a 16 percent carbamide peroxide bleaching gel, Vivastyle, on enamel staining susceptibility. MATERIALS AND METHODS: Thirty bovine specimens were selected and randomly divided into two groups of 15. The experimental group was subjected to Vivastyle gel and then was immersed in coffee for half an hour daily for three weeks. The control group was only immersed in coffee. The teeth were evaluated using a colorimeter to measure L*, a*, b* of each tooth. Value (black to white) is denoted as L*, wheres chroma (a* b*) is denoted as red (+a*), green (_a*), yellow (+b*), and blue (_b*). Total color differences between two colors (deltaE) were calculated using the following formula: deltaE = [(deltaL*)2 + (deltaa*)2+(deltab*)2]: deltaE1.Bleached, AE2: bleached and immersed in coffee, deltaE3: immersed in coffee. RESULTS: Mean differences were: deltaE1 = 9.478, deltaE2 = 13.808 and deltaE3 = 7.230. Paired comparison by use of Duncan test showed there was a significant difference between deltaE1 and deltaE2 (P0.000); and t test showed there was no significant difference between deltaE3 and deltaE1. (P0.08 > 0.05), but deltaE3 showed a significant difference with deltaE2(P0.000). CONCLUSION: After vital bleaching, the enamel staining susceptibility significantly increased.

Animals↗
PubMedDate not supplied

Effects of carbamide peroxide whitening agents on enamel surfaces and caries-like lesion formation: an SEM and polarized light microscopic in vitro study.

Whitening enamel with carbamide peroxide (CP) to remove cosmetically displeasing stains has become common-place in dental practice. This in vitro study evaluated CP treatment effects on enamel surface morphology and caries-like lesion susceptibility. Tooth quarters were prepared from 10 caries-free human molars following a fluoride-free prophylaxis. The tooth quarters were assigned to the following treatment groups: 1) Distobuccal-10 percent NW gel (Nite White, Discus Dental); 2) Distolingual-10 percent PL paste (Platinum, Colgate); 3) Mesiobuccal-16 percent NW gel; and 4) Mesiolingual-Control. Following the manufacturers' recommended treatment, each quarter was sectioned with one portion prepared for SEM and the other portion for caries-like lesion formation. Intact enamel surfaces were present with all treatments. Enamel prism markings with exaggerated prism peripheries and mild to moderate prism core loss were seen with both 10 percent NW and 16 percent NW gels, but was more prominent with 16 percent NW gel. Amorphous surface layers with occasional exposure of indistinct prism markings occurred with 10 percent PL paste. Body of lesion mean depths were 135 microns control, 159 microns 16 percent NW, 144 microns 10 percent NW, and 122 microns 10 percent PL. Lesion depths were significantly different (p < 0.05 DMR paired design) between 10 percent PL and 16 percent NW, and between control and 16 percent NW. Whitening enamel surfaces in vitro with 10 percent carbamide peroxide paste containing dicalcium phosphate dihydrate (Colgate-Platinum) produced an amorphous surface layer and reduced caries susceptibility when compared with 16 percent carbamide peroxide gel (Nite White).

Carbamide Peroxide↗
PubMed1996

Assessing the effects of 10 percent carbamide peroxide on oral soft tissues.

To examine the effects of a 10 percent carbamide peroxide bleaching gel on the oral soft tissues, the authors conducted a prospective, double-blind, placebo-controlled clinical investigation. Fifty-two patients completed a two-week treatment regimen, applying either a placebo or a 10 percent carbamide peroxide gel in a soft tray for eight hours a day. Clinicians examined the participants' oral soft tissues at baseline and one week, two weeks and six weeks after the first treatment. The examiners recorded the Silness and Löe plaque and gingival indexes, nonmarginal gingival index and nongingival oral mucosal index at each examination. The data collected at these intervals did not indicate that any soft tissue damage had occurred as a result of the bleaching regimen.

Adult↗
PubMed1998

Use of different concentrations of carbamide peroxide for bleaching teeth: an in vitro study.

OBJECTIVE: This in vitro study compared the shade changes in extracted teeth during 2 weeks' whitening with 5%, 10%, or 16% carbamide peroxide. METHOD AND MATERIALS: After color calibration, the sole examiner selected 110 extracted unrestored, noncarious teeth, shade A3 or darker on a value-oriented guide. The teeth were randomly distributed into equal color groups. The control group (11 teeth) was treated with 0.9% saline, while the experimental groups (33 teeth each) were treated with 5%, 10%, or 16% carbamide peroxide. The solutions remained on the teeth for 8 hours. The teeth and tray were rinsed with tap water for 2 minutes, then rehydrated in 0.9% saline for 16 hours in the humidifier. The shade was assessed, and the process was repeated daily for 2 weeks. RESULTS: Repeated-measures analysis of variance indicated a significant difference in overall shade values between the control and all carbamide peroxide-treated groups at days 8 and 15. A Kaplan-Meier Survival Analysis indicated a quicker two-tab color change for the 10% and 16% groups than the 5% group. However, continuation of the 5% treatment to 3 weeks resulted in shades that approached the 2-week 10% and 16% values. CONCLUSION: Lower concentrations of carbamide peroxide take longer to whitening teeth but eventually achieve the same result as higher concentrations. Higher concentrations may cause increased sensitivity.

Analysis of Variance↗
PubMed1993

Characterization of enamel exposed to 10% carbamide peroxide bleaching agents.

The purpose of this investigation was to evaluate the effect of three 10% carbamide peroxide bleaching agents on enamel microhardness and surface morphology. Seventy-two enamel slabs were subjected to one of three carbamide peroxide solutions or an artificial saliva solution for 15 hours a day for 2- and 4-week periods. During the remaining 9 hours, slabs were exposed to human saliva in vivo. Although differences were not statistically significant, microhardness values of all treated specimens 2 weeks after treatment were less than those of control specimens. These trends, however, were not evident at 4 weeks. Scanning electron microscopic evaluation revealed significant surface alterations in enamel topography for slabs treated with the bleaching solutions for 4 weeks. The most severe alterations were found in slabs exposed to the lower-pH solutions.

Adult↗
PubMed1995

Acute toxicity of carbamide peroxide and a commercially available tooth-bleaching agent in rats.

Previous studies have indicated that tooth-bleaching agents contain potentially hazardous chemicals. The present study evaluates the acute toxicity of a commercially available tooth-bleaching agent and carbamide peroxide, which is the active bleaching ingredient. Rats were dosed by stomach gavage, i.e., via a stomach tube, with 5, 15, and 50 mg carbamide peroxide/kg body weight and 150 and 500 mg tooth-bleaching agent/kg body weight, corresponding to 15 and 50 mg carbamide peroxide/kg body weight. Animals were killed after either one or 24 h. Autopsies were performed, and the distal part of the esophagus and the stomach were removed and processed for light microscopy investigation. Liver and kidney were evaluated histologically in animals killed after 24 h. Carbamide peroxide gave dose-dependent ulcerations of the gastric mucosa, with the 15 mg/kg body weight as the lowest observed effect level. The lesions were clearly visible after one h and seemed to be healing after 24 h. The ulcerations of the gastric mucosa were more pronounced after exposure to the tooth-bleaching agent than those observed after a comparable dose of carbamide peroxide. This may be attributed to the hydrophobic gel and the content of a carbopol (which increases the tissue adherence and retards the release of oxygen) in the bleaching agent. No apparent injury was observed in livers and kidneys. An exposure limit based on the lowest observed effect level (15 mg carbamide peroxide/kg body weight) and a safety factor of 100 were established and utilized in a risk assessment which indicated that daily human exposure during a bleaching procedure may come close to or even exceed this limit.

Acrylic Resins↗
PubMedDate not supplied

Comparison of 10% carbamide peroxide and sodium perborate for intracoronal bleaching.

The purpose of this study was to compare 10% carbamide peroxide to the combination of sodium perborate and water as intracoronal bleaching agents. Forty-four extracted teeth were discolored in vitro. Bleaching agents were placed intracoronally to the level of the cemento-enamel junction for 12 days; solutions were replaced after four and eight days. Standardized slides were used to rank color changes; a colorimeter was used to quantify color change. After 12 days, 65% of the discolored teeth in the 10% carbamide peroxide group and 67% of the discolored teeth in the sodium perborate group had lightened to their original shade or lighter. While there was no statistical difference between the two treatments, sodium perborate was easier to use.

Borates↗
PubMed2000

A clinical evaluation of 10 percent vs. 15 percent carbamide peroxide tooth-whitening agents.

BACKGROUND: Agents with carbamide peroxide, or CP, in various concentrations are widely prescribed for at-home tooth whitening. It is not clear, however, if the more concentrated gels will whitening teeth to a greater extent, as no controlled clinical trials have been reported. The authors conducted a double-blind study of human subjects to evaluate whether a 15 percent CP tooth-whitening system was more effective than a 10 percent CP system, and to determine if tooth sensitivity increased with use of the higher concentration. METHODS: The authors recruited 57 subjects with maxillary anterior teeth of shade A3 or darker (as gauged against a value-oriented shade guide). The subjects were 18 to 65 years of age and in good general and dental health. After matching the subjects by sex and age, the authors randomly assigned them to either a control group, which used a 10 percent CP whitening agent, or an experimental group, which used a 15 percent CP agent. RESULTS: The results indicated that there was no significant difference in shade change between the groups after one week of treatment (t = 1.455, P = .05), but there was a significant difference at the end of the treatment period (t = 2.303, P < .05), as well as two weeks after treatment concluded (t = 2.248, P < .05). There was no significant difference in sensitivity (t = 1.399, P > .05). CONCLUSIONS: There was a significant difference in color change between the 10 percent CP and 15 percent CP groups at the end of the study period. There was no significant difference in level of tooth sensitivity between the two groups, and the incidence was equal; there was, however, a significant difference in variability of tooth sensitivity between the two groups. CLINICAL IMPLICATIONS: If performed under the careful guidance of a dentist, at-home whitening is an effective treatment, regardless of whether 10 percent CP or 15 percent CP is used. There may be added color change and varying sensitivity with the use of 15 percent CP.

Adolescent↗
PubMed1999

Clinical study of tooth shade lightening from dentist-supervised, patient-applied treatment with two 10% carbamide peroxide gels.

PURPOSE: Prescribed, patient-applied tooth lightening agents, or nightguard vital bleaching, typically utilizes a 10% carbamide peroxide agent applied during nocturnal hours. The purpose of this randomized double-blind study was to compare the amount of tooth color change in two groups of subjects using dentist-supervised, patient-applied 10% carbamide peroxide gel. MATERIALS AND METHODS: One group used Opalescence (Ultradent Products Inc., South Jordan, Utah) and the other NiteWhite Excel (Discus Dental, Inc., Los Angeles, California). Evaluation of tooth color for the six maxillary anterior teeth was done using a Vita shade guide at baseline, 1, 2, and 4 weeks. Subjects were instructed to apply the gel nocturnally using a custom-made soft tray 8 hours per day for 2 weeks. The 16 tabs of the shade guide were ranked according to value from darkest to lightest. The number (1-16) that correlated to the shade tab selected as the match for each tooth was the outcome variable. A Kruskal-Wallis one way analysis of variance on ranks was used. RESULTS: The test revealed no statistically significant difference between Opalescence and NiteWhite Excel for lightening the teeth (p = .807). The color change was still significant after 2 weeks without further bleaching activity. The baseline evaluation of the maxillary incisors and canines for all subjects, regardless of group, demonstrated a significant shade difference, with the canines being darker. This difference was not seen after 2 weeks of active bleaching or at the 4-week evaluation. CLINICAL SIGNIFICANCE: In this study comparing bleaching products, patients using Opalescence and NiteWhite Excel experienced a significant change in the color of their teeth relative to baseline values after 2 weeks of active treatment.

Adult↗
PubMed2006

Surface change of dental amalgam after treatment with 10% carbamide peroxide.

The aim of this study was to explore the effect of bleaching agents on the release of metal ions and change in physical and chemical characteristics of amalgams. Amalgam surface changes resulting from bleaching on amalgam were assessed with inductively coupled plasma atomic emission spectrophotometer, an automatic mercury analyzer, a colorimeter, and atomic force microscopy. Analysis of the release of metal ions indicated that the bleaching agent caused more copper, tin, and mercury ions to be released into the immersion solution. Furthermore, metal ion release increased progressively as immersion time was increased from 42 to 84 hours. Morphological examination revealed no significant effects of the 10% carbamide peroxide bleaching agent on the surface morphology of any of the amalgams tested. These results demonstrated that bleaching using 10% carbamide peroxide did not adversely affect the two types of amalgam tested. In other words, a 10% carbamide peroxide bleaching agent can be safely used on a short-term basis in dentist-monitored bleaching of the dental amalgam.

Analysis of Variance↗
PubMed2004

Shear bond strength after dentin bleaching with 10% carbamide peroxide agents.

This in vitro study evaluated the shear bond strength (SBS) of dentin treated with two 10% carbamide peroxide bleaching agents 15 days after bleaching and storage in artificial saliva. Dentin fragments were randomly divided into 3 groups (n = 20) for the treatment with the two different bleaching agents (Rembrandt 10% or Opalescence 10%) or with a placebo agent, applied to the tooth surface for 8 hours a day. During the remaining time, the specimens were stored in artificial saliva. After 42 days, the fragments were stored in artificial saliva for 14 days. Another group (n = 20) was exposed to distilled and deionized water for 56 days. An adhesive system and microhybrid composite resin were used to prepare specimens for the SBS test. SBS tests were performed and the fractured surfaces were visually examined using a stereoscope at 30 x magnification. The analysis of variance (ANOVA) and SIDAK tests showed higher SBS values for dentin treated with Opalescence 10% than for dentin treated with Rembrandt 10% or placebo. Groups treated with Rembrandt 10%, Opalescence 10% or placebo did not differ from the group treated with distilled and deionized water. Ten percent carbamide peroxide agents or a placebo agent caused no differences in SBS of dentin after 15 days of storage in artificial saliva.

Analysis of Variance↗
PubMed2006

Effect of 10% carbamide peroxide dental bleaching on microhardness of filled and unfilled sealant materials.

PURPOSE: The purpose of this study was to quantitatively evaluate the effect of 10% carbamide peroxide on the microhardness of pit and fissure sealant materials. METHODS: Fluroshield, Vitroseal Alfa, and one unfilled (Clinpro) sealants were placed in Teflon matrices (4 mm in diameter by 2 mm in height) and polymerized for 40 seconds. A total of 20 specimens were prepared for each material, in which half were assigned as the control group (stored in artificial saliva and no bleaching treatment). For the remaining half, Clarigel Gold bleaching agent (10% carbamide peroxide) was placed over the specimen surface for 4 hours/day during 4 weeks. When specimens were not under bleaching treatment, they were kept in artificial saliva. Afterwards, specimens were subjected to Knoop microhardness testing using a 25-g load for 5 seconds. Five measurements were made on the sealants' surfaces and then calculated in Knoop hardness values. The data were statistically analyzed by two-way analysis of variance and Tukey's tests with a 5% confidence level. RESULTS: The results of this in vitro study showed that the application of a carbamide peroxide-based bleaching material significantly affected the microhardness values of filled sealant materials. The bleaching agent did not affect the microhardness of the unfilled sealant. CLINICAL SIGNIFICANCE The results of this in vitro study suggest that the bleaching agents altered the surface hardness of filled sealant restorative materials. This could possibly lead to increased wear and surface roughness.

Carbamide Peroxide↗
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↗
PubMed1998

Clinical evaluation of two carbamide peroxide tooth-whitening agents.

A blinded study was conducted to evaluate the efficacy and safety of a dentist-prescribed, accelerated carbamide peroxide tooth-whitening system. Fifty-one patients with discolored teeth completed a clinical trial using an overnight bleaching regimen. One group used an experimental bleaching (whitening) regimen with 10% carbamide peroxide bleaching paste, and another group used the Colgate Platinum Professional Overnight Whitening System. The study included an initial 1-week control/compliance phase using a placebo gel, followed by a 1-week active phase using the assigned bleaching agent. The shade of each participant's maxillary anterior teeth was evaluated by 2 trained and calibrated evaluators at the start of the control/compliance phase, the beginning of the active phase, and days 3, 5, and 7 of the active phase. A value-oriented Vita shade guide with 16 rankings was used to measure color changes, and the number of shade guide units of change (delta sgu) was calculated. Potential side effects, such as tooth hypersensitivity and gingival irritation, also were assessed at each recall examination, as well as recorded by the patients in their daily diaries. At the end of the 7-day active phase, the mean delta sgu for the group using the experimental bleaching agent was 7.1 +/- 2.4, and for the Colgate Platinum Overnight group, the delta sgu was 7.5 +/- 2.2. There were no statistically significant (p > or = 0.05) differences between the results of both groups at the 0-, 3-, 5-, and 7-day evaluations. After 7 days, the change in shade guide units for both groups ranged from 3 to 13 units, far exceeding the minimum required change by the American Dental Association Guidelines (delta sgu = 2 units) for demonstrating efficacy. There was no statistical difference in the whitening achieved at day 5 vs. day 7 for either tooth-whitening group. There were no notable changes in any gingival, bleeding, or plaque indexes for the 50 patients completing the active phase. The number of days of mild tooth sensitivity during the active phase was 0.9 +/- 1.3 days for the experimental agent group and 1.1 +/- 1.5 days for the Colgate Platinum group.

Adolescent↗
PubMed2005

Carbamide peroxide bleaching agents: effects on surface roughness of enamel, composite and porcelain.

This study examined the effect of 10 and 35% carbamide peroxide bleaching agents on the surface roughness of enamel, feldspathic porcelain, and microfilled and microhybrid composite resins. Standardized cylindrical specimens were prepared for restorative materials. Enamel samples were obtained from buccal and lingual surfaces of human molars. Samples from each substrate were divided in three subgroups (n=10), according to surface treatment: distilled water (control), and 10 and 35% carbamide peroxide. The 10% agent was applied 3 h daily and the 35% agent was applied for 30 min/week, at 37 degrees C, during 21 days. Control samples remained stored in distilled water, at 37 degrees C. Roughness measurements (Ra, microm) were made at 24 h and repeated after 7, 14 and 21 days of exposure. Data were analyzed using ANOVA (split-plot design) and Tukey's test (5% significance level). Samples from control groups showed no significant alteration during all test periods, while for exposure to 10% agent, only the porcelain presented a rougher surface after 21 days (p<0.05). For the 35% product, roughness means significantly increased during the first and second weeks for enamel (p<0.05), and after 21 days for porcelain (p<0.05) and for the microhybrid composite (p<0.05). Microfilled samples showed no significant alteration throughout the 21-day period, regardless of the surface treatment.

Aluminum Silicates↗
PubMed2006

Spectrophotometric and visual evaluation of vital tooth bleaching employing different carbamide peroxide concentrations.

OBJECTIVE: The aim of the present study was to assess the hypothesis that the efficiency of vital tooth bleaching depends on the concentration of carbamide peroxide agents. METHODS: The front teeth of 30 subjects were bleached at home with 10%, 17% or 0% (control) carbamide peroxide for 1 week in a double-blind study design. Tooth shades were determined in the LCH color space employing a visual shade matching system and a spectrophotometer. Differences in lightness (Deltal), chroma (Deltac) and hue (Deltah) were measured to assess the treatment process. After 2 weeks of no treatment, tooth shades were evaluated again to assess stability of the resultant shade. RESULTS: First-time changes of shade values could be observed after 3 days in the 17% group and after 7 days in the 10% group. After 1 week, in both the 17% group (Deltal: 2.80, Deltac: -3.33, Deltah: 0.60) and the 10% group (Deltal: 2.61, Deltac: -2.54, Deltah: 0.09), values for lightness and chroma were significantly different from the control (Deltal: 0.13, Deltac: 0.14, Deltah: 0.21, p<0.05) with no difference between the test groups (p>0.05). Two weeks after treatment, a rebound of shade values could be observed in the test groups (p<0.05). SIGNIFICANCE: The study indicates that higher concentration bleaching agents might whiten teeth faster with major changes in lightness and chroma. However, by bleaching daily for 1 week, similar effects can be achieved with both a high and a low concentration agent. After treatment, a regression of the resultant shade has to be expected.

Carbamide Peroxide↗
PubMed2004

Use of 37% carbamide peroxide in the walking bleach technique: a case report.

Dental bleaching represents an effective, conservative, and relatively low-cost method for improving the appearance of discolored pulpless teeth. Among the bleaching techniques, the walking bleach technique with sodium perborate associated with water or hydrogen peroxide stands out because of its esthetic results and safety. A modified walking bleach technique with the use of 37% carbamide peroxide as the bleaching agent is presented. Additionally, the adverse effects of dental bleaching in the following restorative procedures are discussed, showing the advantages with the use of 37% carbamide peroxide.

Carbamide Peroxide↗