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PubMed2000

Effect of whitening agents containing carbamide peroxide on cariogenic bacteria.

PURPOSE: The purpose of this study was to investigate the in vitro antibacterial effects of three different carbamide peroxide products (Nitewhite, Opalescence, and Proxigel) on cariogenic microorganisms (mutans streptococci [MS] and lactobacilli), and to evaluate the effects of a 10% carbamide peroxide solution (Proxigel) on salivary levels of MS and lactobacilli clinically. MATERIALS AND METHODS: Growth inhibition studies were performed to determine the concentration and exposure time of carbamide peroxide to give total inhibition of recoverable growth of MS and lactobacilli. Paraffin-stimulated saliva samples were collected from subjects before and after 6 weeks of treatment with 10% carbamide peroxide in bleaching trays, and levels of MS and lactobacilli were determined. RESULTS: The growth inhibition studies showed no visible growth of MS or lactobacilli at 24-, 48-, or 72-hour incubation, after a 2-hour exposure to 1% carbamide peroxide. Identical results were obtained with all three carbamide peroxide products. In the clinical study, the mean salivary MS levels, expressed as logarithm colony-forming units per milliliter (CFU/mL), were 5.38 for the pretreatment samples and 5.23 for the post-treatment samples. The differences were not statistically significant (p > .05). However, there was a reduction in logarithm lactobacilli counts from a mean of 4.12 pretreatment to a mean of 2.74 post-treatment. This was statistically significant (p < .05).

Adult↗
PubMed1999

In vitro penetration of the pulp chamber by three brands of carbamide peroxide.

PURPOSE: Vital tooth bleaching has become a popular procedure for whitening teeth. Most home bleaching products contain 10% carbamide peroxide. The purpose of this in vitro study was to measure the quantity of hydrogen peroxide that reaches the pulp chamber from three carbamide peroxide products: Opalescence, Sparkle, and Rembrandt. MATERIALS AND METHODS: Seventy roots of extracted premolars were amputated approximately 3 mm apical to the cementoenamel junction, and the pulp tissues were removed. They were divided into three experimental groups (n = 20) and a control group of 10 teeth. An acetate buffer solution was placed in the pulp chamber before the crown was exposed to the bleaching agent at 37 degrees C for 25 minutes. The buffer solution was removed and reacted with leukocrystal violet and horseradish peroxidase. The optical density of blue color that developed was measured at a wavelength of 596 nm and read from a standard curve for hydrogen peroxide quantity. RESULTS: The measured amounts of hydrogen peroxide were 3.605 +/- 1.405, 1.282 +/- 0.762, and 0.339 +/- 0.251 micrograms for the Opalescence, Sparkle, and Rembrandt groups, respectively. A statistically significant difference in the hydrogen peroxide levels was observed by analysis of variance (p < .05) among the three groups. It was concluded that the penetration of commercial bleaching products was different even though the products were labeled as having the same 10% carbamide peroxide. CLINICAL SIGNIFICANCE: Carbamide peroxide penetration to the pulp varies significantly for various commercial bleaching products. This may result in different levels of tooth sensitivity or bleaching efficacy.

Carbamide Peroxide↗
PubMed2005

Effects of a 10% carbamide peroxide bleaching agent on roughness and microhardness of packable composite resins.

PURPOSE: Bleaching agents containing 10% carbamide peroxide may be applied to the surface of preexisting packable resin-based composite restorations. The aim of this in vitro study was to evaluate the effect of a 10% carbamide peroxide bleaching agent (Review, SS White, Rio de Janeiro, Brazil) on surface roughness and microhardness of three packable resin-based composites (Fill Magic condensable, Vigodent, Rio de Janeiro, Brazil; Alert, Jeneric Pentron, Wallingford, CT, USA; Definite, Degussa, Hanau, Germany). MATERIALS AND METHODS: For the control (no bleaching) and experimental (bleaching treatment) groups, 12 specimens of each material were prepared in cylindrical acrylic molds. The experimental specimens were exposed to the bleaching agent for 6 hours a day for 3 weeks. During the remaining time (18 h), they were stored in artificial saliva. The control specimens remained immersed in artificial saliva throughout the experiment. Surface roughness and microhardness measurements were performed on the top surface of each specimen. RESULTS: Analysis of variance and the Tukey test showed no significant differences in roughness among the packable composites evaluated (p = .18), but those submitted to the treatment with a 10% carbamide peroxide bleaching agent displayed significantly higher mean surface roughness than did the corresponding control group for each material. For the microhardness tests, there were significant differences among materials (p < .0001). Alert showed the highest microhardness values followed by Definite and Fill Magic condensable. CONCLUSIONS: Ten percent carbamide peroxide bleaching agents may change the surface roughness of packable composites, but they do not alter their microhardness. CLINICAL SIGNIFICANCE: Under the conditions of this study, a 3-week bleaching regimen with 10% carbamide peroxide agents affected the roughness of packable composites. Nevertheless, the surface microhardness was not affected, although there were differences among the materials evaluated inherent to their composition.

Carbamide Peroxide↗
PubMed2004

Safety evaluation of a novel whitening gel, containing 6% hydrogen peroxide and a commercially available whitening gel containing 18% carbamide peroxide in an exaggerated use clinical study.

OBJECTIVES: The aim of this study was to compare the effect on oral soft tissue of a self-applied tooth whitening gel containing 6% hydrogen peroxide (Xtra White) with a marketed paint-on whitening gel containing 18% carbamide peroxide (Colgate Simply White) after 2-weeks of using products four times daily. METHODS: A 2-week, examiner-blind, stratified, parallel design clinical trial was conducted. Twenty subjects were divided into two groups, balanced according to age and gender. Subjects followed a 2-week, twice-daily regimen of brushing with standard fluoride toothpaste and applied gel product to facial aspects of six upper and six lower incisors/canines, twice in succession with 30 min between applications. Soft tissue examinations were performed on Day 1, before the first application of the test products, and on Day 2, 5, 8 and 15. RESULTS: During the 2-week treatment period, twelve adverse reactions were recorded as potentially attributable to the study products, evenly split between the two test groups. All reports were mild in symptoms and resolved without the need of medical intervention. None of the subjects experiencing an adverse event requested to be withdrawn from the study. CONCLUSIONS: Under the exaggerated use conditions of this test, there was no evidence to suggest that either of the whitening gels produced irritation that was building or developing during the course of the study. It is concluded that both products are safe for their intended use.

Adolescent↗
PubMed2004

Effect of fluoride and 10% carbamide peroxide on the surface roughness of low-fusing and ultra low-fusing porcelain.

STATEMENT OF PROBLEM: The effect of repeated applications of fluoride solutions and 10% carbamide peroxide on the surface roughness of newer dental porcelains is not completely known. PURPOSE: The purpose of this study was to compare the surface roughness of 3 different porcelains when exposed to 2 fluoride solutions, a 10% solution of carbamide peroxide, and distilled water. MATERIAL AND METHODS: Forty discs (10-mm diameter, 2 mm thick) were made of each of the following porcelains: feldspathic porcelain (Ceramco II), low-fusing porcelain (Finesse), and an aluminous porcelain (All-Ceram). Each disc was abraded with a medium-grit diamond bur and auto-glazed. One side of each disc was abraded with a diamond bur and polished using a porcelain polishing kit to simulate a chairside adjustment and polishing. The discs (10 specimens/group) were immersed in 1.23% APF, 0.4% stannous fluoride, 10% carbamide peroxide, and distilled water for 50 seconds (control). The discs in the 10% carbamide peroxide solution were immersed for 48 hours. The surface of each disc was evaluated with surface profilometry (0.1 mm/s speed, 600-microm range). The data were analyzed by factorial analysis of variance and a Tukey multiple comparison test, (alpha=.05). RESULTS: The data showed that the acidulated phosphate fluoride etched the auto-glazed surface of all 3 porcelains. For Finesse specimens, the mean Ra values for the auto-glazed surface were significantly higher than that of the control after immersion in 1.23% APF (mean Ra 0.3 +/- 0.06 microm, P<.031). All-Ceram auto-glazed surface specimens had a significantly higher mean Ra value when immersed in the 3 solutions than the control (1.23% APF, 0.4% stannous fluoride, and 10% carbamide peroxide, 0.245 +/- 0.115 microm, 0.22 +/- 0.104 microm, 0.22 +/- 0.04 microm, respectively; P<.002). Ceramco II specimens were affected by all 3 solutions, with the auto-glazed surface having higher Ra values (1.23% APF, 0.4% stannous fluoride, and 10% carbamide peroxide, with mean Ra values of 0.35 +/- 0.1 microm, 0.26 +/- 0.08 microm, and 0.24 +/-.0.05 microm, respectively, P=.001). Immersion in the 3 solutions had no effect on the polished surfaces of all-ceramic specimens tested. CONCLUSION: Prior to the use of fluoride and 10% carbamide peroxide, dentists should ascertain the type of porcelain restoration present to prevent a roughened surface from occurring.

Acidulated Phosphate Fluoride↗
PubMedDate not supplied

Bleaching primary teeth with 10% carbamide peroxide.

Bleaching teeth with 10% carbamide peroxide in a custom-fitted tray has been popular for more than 10 years. However, primary teeth are seldom considered for bleaching due to the need for compliance by the child and the natural whiteness of the primary teeth. This report describes an indication-teeth darkened from trauma-as well as the technique and outcome for bleaching discolored primary teeth.

Carbamide Peroxide↗
PubMed2004

An in vitro comparison of the bleaching efficacy of 35% carbamide peroxide with established intracoronal bleaching agents.

AIM: To evaluate the bleaching efficacy of 35% carbamide peroxide, 35% hydrogen peroxide and sodium perborate for intracoronal bleaching of root filled discoloured teeth. METHODOLOGY: Extracted premolars were artificially stained using whole blood then root canal treatment was performed. After obturation, a 2 mm intermediate base was placed 1 mm below the buccal amelo-cemental junction. Intracoronal bleaching was performed in 11 teeth per group, using either 35% carbamide peroxide gel (group CP), 35% hydrogen peroxide gel (group HP) or sodium perborate mixed with distilled water (group SP). The bleaching agents were replaced after 7 days. The shade of the teeth was evaluated at day 0, 7 and 14. The results were analysed using Kruskal-Wallis one-way analysis of variance and Mann-Whitney U-test. RESULTS: At the end of 7 days, both groups CP and HP lightened by 8 +/- 3 Vita tab positions, respectively, whereas group SP lightened by 5 +/- 3 tab positions (P < 0.05). At the end of the second bleaching period at day 14, group CP and HP lightened by a further 2 +/- 2 and 2 +/- 3 tab positions, respectively, whereas group SP lightened by a further 3 +/- 4 tab positions. There were no statistical differences between groups at day 14. CONCLUSIONS: Thirty-five per cent carbamide peroxide and 35% hydrogen peroxide were equally effective for intracoronal bleaching, and significantly better than sodium perborate after 7 days. After 14 days, there were no significant differences between the groups. Thirty-five per cent carbamide peroxide can be recommended as an equally effective alternative to hydrogen peroxide for intracoronal bleaching.

Adolescent↗
PubMed2005

Microcomputerised tomography evaluation of 10% carbamide peroxide applied to enamel.

OBJECTIVES: There is still some controversy in the dental literature whether carbamide peroxide bleaching causes demineralization of teeth. One of the reasons for this controversy is that there is as yet no reliable, non-destructive in vitro method for assessing mineral loss in bleached teeth. The objective of this study was to investigate the possible demineralization effect of 10% carbamide peroxide bleaching agent on enamel and dentine non-destructively. METHODS: microCT images were obtained of 12 human molar tooth sections. These sections had 10% carbamide peroxide applied for eight hours a day over a period of 15 days. Further tomographic images were obtained and the mineral content prior to and post bleaching assessed. RESULTS: A total of 144 regions were evaluated using the image processing language available in the work station. The application of 10% carbamide peroxide was found to cause demineralization of the enamel extended to a depth of 50 microm below the enamel surface (Paired t-test, p<0.05). CONCLUSIONS: This study confirmed that microCT was indeed a highly suitable method for assessing mineral content of dental enamel after bleach application. It is recommended that application of bleaching agents should be carefully considered in patients susceptible to caries and tooth wear.

Carbamide Peroxide↗
PubMed2006

Influence of carbamide peroxide on enamel fluoride uptake.

OBJECTIVE: Aim of the study was to evaluate the influence of carbamide peroxide (CP) on enamel fluoride uptake by comparing enamel fluoride uptake from a 1% amine fluoride (AmF) gel with the fluoride acquisition from a 10% carbamide peroxide agent supplemented with 1% AmF. MATERIALS AND METHODS: Three enamel cylinders (4mm in diameter) were prepared from the buccal surfaces of 60 bovine incisors. One sample of each tooth was used for determination of baseline fluoride content of the respective tooth. The two remaining samples were allocated to the experimental series 1 or 2, respectively. Each series consisted of five experimental groups (A-E, n=12) and differed with respect to the length of the treatment period with the gels (A-D). The experimentally designed gels (pH 5.5) used in the study were as follows: A (10% CP), B (10% CP, 1% F(-) as AmF), C (1% F(-) as AmF), D (no CP, no F(-)) and were formulated on the same basis. The enamel samples were covered for 4h with the respective gel at 37 degrees C and were then transferred to artificial saliva for 20 h (series 1). The samples of group E served as controls and were not treated with a gel. In series 2, treatment with the gels and storage in saliva was conducted seven times. Finally, the samples were assessed for KOH-soluble and structurally bound fluoride. RESULTS: Only the enamel samples treated with the fluoridated bleaching gel (group B) and with the amine fluoride gel (group C) exhibited significant fluoride acquisition. Thereby, both gels showed significantly lower uptake in series 1 as compared to series 2. Both KOH-soluble and structurally bound fluoride acquisition was significantly higher in group C than in group B. CONCLUSION: Treatment with a carbamide peroxide gel supplemented with amine fluoride causes less fluoride acquisition in enamel than a pure amine fluoride gel. Under the conditions of the study, it is assumed that carbamide peroxide seems to influence enamel fluoride uptake.

Amines↗
PubMedDate not supplied

Effect of potassium nitrate and fluoride on carbamide peroxide bleaching.

OBJECTIVES: The purpose of this study was to assess the effect on tooth sensitivity when potassium nitrate and fluoride were added to a 10% carbamide peroxide bleaching gel. METHOD AND MATERIALS: Seventeen maxillary and four mandibular arches were bleached using the at-home bleaching technique. The bleaching treatment consisted of the simultaneous use of a 10% carbamide peroxide gel containing 3% potassium nitrate wt/vol and 0.11 fluoride ion wt/vol on one side of the midline and a 10% carbamide peroxide gel only (control) on the other side of the midline for 14 nights. A visual analog scale for each side of the dental arch was used by the patients to assess tooth sensitivity and tooth whitening. Preoperative and postoperative photographs were also taken. RESULTS: The addition of potassium nitrate and fluoride significantly decreased the total tooth sensitivity reported by the patients. The addition did not significantly change the whitening efficacy of the carbamide peroxide bleach. CONCLUSION: A 10% carbamide peroxide bleaching gel containing potassium nitrate and fluoride produced less tooth sensitivity than did the control bleaching gel during a 2-week at-home bleaching treatment.

Adult↗
PubMedDate not supplied

Internal bleaching with 10% carbamide peroxide in vitro.

This in vitro study assessed the efficacy of 10% carbamide peroxide to internally bleach discolored teeth. Following pulp removal, 38 tooth crowns were stained with erythrocytes and bleached 3 times over 14 days using either 10% carbamide peroxide or 30% H2O2 and sodium perborate. The pulp chambers were subsequently filled, and the tooth crowns stored for 3 months. The shades of the crowns were measured using reflectance spectroscopy prior to and at several time points following bleaching. Using statistical analysis, the authors determined that both materials significantly improved the shade of the crowns, and that 10% carbamide peroxide could be utilized clinically to internally bleach nonvital discolored teeth.

Analysis of Variance↗
PubMed2000

Protective effect of Copalite surface coating on mercury release from dental amalgam following treatment with carbamide peroxide.

The effect of Copalite coating on mercury release from dental amalgam following treatment with 10%, 20%, 30% and 40% carbamide peroxide was assessed in vitro, using a cold-vapour atomic absorption Mercury Analyzer System. Eighty samples of dental amalgam were automatically mixed in a dental amalgamator and condensed into silicon embedding molds. Forty amalgam samples were coated with three uniform layers of Copalite intermediary varnish and the other 40 samples were left uncoated. The coated and non-coated amalgam samples were exposed for 24 h to 10%, 20%, 30% or 40% carbamide peroxide preparations and compared with samples exposed to phosphate buffer. In the non-coated samples a significant increase of mercury concentration in solution was found following exposure to all carbamide peroxide preparations tested. Mercury concentration was directly related to carbamide peroxide concentration. In the Copalite-coated samples, significantly lower concentrations of mercury in solution were found as compared to the non-coated samples (P < 0.01). In conclusion, exposure of amalgam restorations to 10%-40% carbamide peroxide-based bleaching agents increased the mercury release. Pre-coating of the external amalgam surfaces with Copalite significantly reduced the release of mercury.

Analysis of Variance↗
PubMed2003

The effects of seven carbamide peroxide bleaching agents on enamel microhardness over time.

BACKGROUND: Different concentrations of carbamide peroxide (10 to 22 percent) have been used successfully as bleaching agents, but the adverse effects on enamel microhardness at different times are unknown. METHODS: The authors analyzed seven bleaching agents and a placebo. The agents were applied on the surface of human dental fragments for eight hours per day for 42 days and stored in vials containing artificial saliva. Microhardness measurements were performed at baseline, eight hours and seven, 14, 21, 28, 35 and 42 days, as well as at seven and 14 days after treatment had ended. RESULTS: Enamel treated with different bleaching agents or a placebo experienced a similar decrease in microhardness values over time, with the exception of fragments exposed to Opalescence PF 20 percent (Ultradent Products, South Jordan, Utah), or OPA20. Until the 49th day, the enamel exposed to OPA20 exhibited the lowest differences from baseline values. After 14 posttreatment days, enamel treated with placebo, Nite White 10 percent Excel (Discus Dental, Los Angeles), Nite White 16 percent Excel and Opalescence 10 percent exhibited the greatest differences from baseline values. An increase in enamel microhardness occurred at the end of the posttreatment period, although baseline values were not reached. CONCLUSIONS: Different concentrations of carbamide peroxide agents result in decreases in enamel microhardness. A post-bleaching period in artificial saliva resulted in recovery of baseline microhardness values (one agent) or an increase in values, although baseline values were not reached for these products. Clinical Implications. Higher concentrations of carbamide peroxide containing 0.11 percent ion fluoride can bleach teeth in a shorter period, with fewer hazardous effects on the enamel mineral content.

Carbamide Peroxide↗
PubMed2003

Effects of a carbamide peroxide agent and desensitizing dentifrices on enamel microhardness.

PURPOSE: To evaluate the in vitro microhardness of enamel treated with a 10% carbamide peroxide agent and two desensitizing dentifrices at different bleaching times. MATERIALS AND METHODS: A 10% carbamide peroxide bleaching agent was evaluated (Rembrandt 10%) (REM). A placebo agent was used as a control group (PLA). The bleaching and the placebo agents were applied to human enamel dental fragments for 8 hours per day, followed by immersion for 5 minutes in a slurry solution of desensitizing dentifrices: Sensodyne (S) or Sensodyne Fluor (SF). During the remaining time, the enamel fragments were individually stored in 13.5 ml of artificial saliva. Knoop microhardness measurements were performed at baseline, 8 hours, 7, 14, 21, 28, 35 and 42 days of treatment and at 7 and 14 days of a post-treatment period. RESULTS: Analysis of variance and Tukey's test showed no differences in enamel microhardness for REM + SF (P=0.069) and PLA + SF (P=0.93) within each time interval. The dental fragments treated with REM + S and PLA + S showed an increase in microhardness values within each time interval (P<0.0001). There were significant differences among the treatment agents from the 28th to the 56th day. The use of 10% carbamide peroxide bleaching and a desensitizing dentifrice significantly increased the enamel microhardness values during the bleaching treatment and after 14 days after the completion of the treatment. After the post-treatment period, the enamel fragments treated with a placebo agent and with a 10% carbamide peroxide agent and with a desensitizing fluoride dentifrice maintained the baseline values.

Carbamide Peroxide↗
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

Degradation of bleaching gels in vivo as a function of tray design and carbamide peroxide concentration.

This study determined the degradation of nine bleaching agents with different concentrations after two hours in vivo following the manufacturers' recommendations. The nine carbamide peroxide products are 10%, 15% and 20% Opalescence, 10%, 15% and 22% Rembrandt and 10%, 16% and 22% Nite White Excel 2. Each subject wore the tray with the bleaching agent for two hours on three separate occasions. The amount of remaining carbamide peroxide was determined after each use. Evaluation of remaining amount of carbamide peroxide was calculated by the US Pharmacopeia method. The study showed that the total carbamide peroxide percent recovered was significantly higher for Opalescence products (47% to 54%) compared to Nite White (22% to 25%) and Rembrandt bleaching gels (15% to 16%). It concluded that this difference was mostly due to the use of facial reservoirs with Opalescence products, and also that whitening gel in trays with reservoirs and trays without reservoirs degraded at the same rate.

Adult↗
PubMed1994

Change in pH of plaque and 10% carbamide peroxide solution during nightguard vital bleaching treatment.

The purpose of this study was to evaluate in vivo changes in the pH of plaque and of a 10% carbamide peroxide solution occurring within the bleaching guard during a 2-hour nightguard vital bleaching procedure. Baseline pH values for plaque and the carbamide peroxide solution were established. A small hole was placed in the anterior interproximal region of the guard to allow placement of the pH electrode. The pH of the carbamide peroxide solution was measured at 5-minute intervals. After 2 hours, the guard was removed and pH of the plaque was remeasured. The procedure was repeated three times on each of four subjects. The mean baseline pH reading for plaque was 6.31 and mean final pH reading was 6.86. The difference was statistically significant. At initial placement of the carbamide peroxide-filled guard, the mean intraguard pH was 4.50 (range of 2.80 to 7.80). The mean peak intraguard pH of 8.06 (range of 7.30 to 8.43), which was significantly different from baseline, was obtained within 31 minutes. The pH of plaque, saliva, and a 10% carbamide peroxide bleaching solution within the guard increased significantly during bleaching and remained significantly elevated for the duration of the study (2 hours).

Carbamide Peroxide↗
PubMed2000

Effect of 10% carbamide peroxide bleaching gel on enamel microhardness, microstructure, and mineral content.

The effect of 10% carbamide peroxide on human enamel subsurface layers was examined. Microhardness, microstructure, and mineral content were studied in such a manner that control and test side were located on the same tooth. Longitudinally sectioned samples were obtained from six teeth and Vickers microhardness of the enamel was measured. Enamel microstructure was analyzed using a scanning electron microscope and subjected to electron probe microanalysis for chemical analysis of calcium (Ca) and phosphorus (P). The concentration of Ca in the bleaching gel was measured spectrophotometrically and the concentration of P was measured photometrically. Results showed that a bleaching gel of 10% carbamide peroxide did not significantly affect the microhardness of the enamel. Scanning electron microscopic analysis showed local changes in enamel microstructure similar to those of initial caries. Electron probe microanalysis showed lowered concentrations of Ca and P; in addition the Ca:P ratio was lowered. There was some Ca and P in the bleaching gel after use. It is concluded that 10% carbamide peroxide causes local microstructural and chemical changes in enamel that are likely not clinically significant.

Adolescent↗