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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↗

PubMed2004

In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing.

The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive pastes. A perfilometer was used to measure roughness average (Ra) values of the initial surface roughness and at each 7-day-interval after the beginning of treatment. The bleaching was performed on the surface of the fragments for 1 hour a week, and the surface cleaning treatment for 3 minutes daily. The samples were stored in individual receptacles with artificial saliva. Analysis of variance and the Tukey test revealed significant differences in surface roughness values for G2 and G3, which showed an increase in roughness over time; G1 and G4 showed no significant roughness differences. The bleaching with 35% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with brushing with abrasive dentifrices, there was a significant increase in roughness values.

Analysis of Variance↗

PubMed1996

Antibacterial activity of 10% carbamide peroxide bleaching agents.

The antibacterial activity of three commercial 10% carbamide peroxide bleaching agents (Nite White, Karisma, and Opalescence) on Streptococcus mutans, Streptococcus mitis, Streptococcus sanguis, Lactobacillus casei, and Lactobacillus acidophilus was examined. Chlorhexidine (0.2%) was used as a positive control. Test materials and control solution were inserted in wells punched on the surface of disk sensitivity agars seeded with bacteria. After incubation of 24 to 48 h, zones of inhibition were measured. All three of the test materials displayed greater inhibition than the control. The pH of the solutions did not effect the bacterial inhibition.

Anti-Infective Agents, Local↗

PubMed2003

Effects of bleaching with carbamide peroxide gels on microhardness of restoration materials.

The objective of this in vitro study was to quantitatively assess the effects of bleaching with 10 and 15% carbamide peroxide (CP) on restoration materials by performing superficial microhardness analysis. Acrylic cylindrical containers (4 x 2 mm) were filled with the following restoration products: Charisma (Heraues Kulzer, Vila Santa Catarina, São Paulo, Brazil), Durafill VS (Heraeus Kulzer), Vitremer (3M, Sumaré, São Paulo, Brazil), Dyract (Dentsply, Petrópolis, Rio de Janeiro, Brazil), and Permite C (SDI, São Paulo, São Paulo, Brazil). Sixty samples were prepared of each restoration material. Twenty samples received bleaching treatment with 10% CP, 20 samples received bleaching treatment with 15% CP, and 20 samples were kept submerged in artificial saliva, which was replaced daily. The treatment consisted of immersion of the specimens in 1 cm3 of CP at 10 and 15% for 6 hours per day during 3 weeks, whereupon the test specimens were washed, dried, and kept immersed in artificial saliva for 18 hours. Then the test and control specimens were analyzed using a microhardness gauge. The Knoop Hardness Number (KHN) was taken for each test and control specimen at five different locations by applying a 25 g force for 20 seconds. The values obtained were transformed into KHNs and the mean was calculated. The data were submitted to statistical analysis by analysis of variance and Tukey test, p < .05. The means/standard deviations were as follows: Charisma: CP 10% 38.52/4.08, CP 15% 34.31/6.13, saliva 37.36/4.48; Durafill VS: CP 10% 18.65/1.65, CP 15% 19.38/2.23, saliva 18.27/1.43; Dyract AP: CP 10% 30.26/2.81, CP 15% 28.64/5.44, saliva 33.88/3.46; Vitremer: CP 10% 28.15/3.04, CP 15% 17.40/3.11, saliva 40.93/4.18; and Permite C: CP 10% 183.50/27.09, CP 15% 159.45/5.78, saliva 215.80/26.15. A decrease in microhardness was observed for the materials Dyract AP, Vitremer, and Permite C after treatment with CP at 10 and 15%, whereas no effect on either of the two composites (Charisma and Durafill) was verified. CLINICAL SIGNIFICANCE The application of the carbamide peroxide gels at 10 and 15% did not alter the microhardness of the composite resins Charisma and Durafill. In situ and clinical studies are necessary to enable one to conclude that the reduction in microhardness of the materials effectively results in clinical harm to the restorations.

Analysis of Variance↗

PubMed1998

Simultaneous bleaching of vital teeth and an open-chamber nonvital tooth with 10% carbamide peroxide.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of bleaching a nonvital tooth with an open pulp chamber while simultaneously bleaching the other vital teeth with 10% carbamide peroxide. METHOD AND MATERIALS: Ten discolored nonvital teeth were treated. Each nonvital tooth was prepared as in the conventional "walking bleaching" fashion, so that the gutta-percha was sealed from the pulp chamber. The 10% carbamide peroxide was injected into the chamber of the nonvital tooth and loaded into the custom-fitted tray for all teeth. The nonvital teeth were bleached from both the inside and the outside. The patient closed the orifice with a cotton pellet during the day and changed the cotton pellet after meals. The patient applied fresh solution nightly. RESULTS: All teeth were successfully lightened. The time required to lighten the nonvital tooth was related to the duration of the discoloration. CONCLUSION: With proper patient selection and education, this technique can provide an effective way to lighten nonvital and vital teeth simultaneously, especially where extended treatment time may be required for difficult discolorations.

Adult↗

PubMed2004

[Effect of 10-15% carbamide peroxide on enamel fluoride concentration in vital bleached teeth].

The objective of the study was to evaluate the concentration of fluoride in human enamel before and after bleaching using 10-15% carbamide peroxide and after application of the fluoride varnish. Microsamples of enamel were collected using acid biopsy and the concentration of fluoride in the superficial and underlying layer was assayed. No significant differences were observed in the concentration of fluoride in both layers of enamel before and after bleaching as well as after varnish application. Bleaching with 10-15% carbamide peroxide has no influence on the concentration of fluoride in enamel.

Biopsy↗

PubMed1999

Clinical trial of three 10% carbamide peroxide bleaching products.

BACKGROUND: A profusion of commercial bleaching systems exists on the market today, but there are few clinical comparisons of these systems. METHODS: In this study, three different commercial 10% carbamide peroxide bleaching systems were used by 24 patients in an overnight protocol for two weeks. Each patient used two of the bleaching products simultaneously in a side-by-side comparison. RESULTS: The mean onset of tooth whitening was 2.4 +/- 1.7 days. Tooth sensitivity was the most frequent side effect, as 64% of the patients reported tooth sensitivity occurring after 4.8 +/- 4.1 days and lasting for 5.0 +/- 3.8 days. Although intrapatient differences were recorded for the three commercial 10% carbamide peroxide bleaching systems by the patients, there were no statistical differences in the time of onset of subjective tooth whitening and the onset, frequency and duration of tooth sensitivity among the three commercial bleaching systems when compared pairwise or independently (p < 0.05). CONCLUSION: Selection of which bleaching product to use should be based on the concentration of the active ingredient, the viscosity of the product and other marketing features. Further research is needed to investigate the causes of tooth sensitivity and methods to reduce its severity and frequency.

Adolescent↗

PubMed2006

Brushing effect of abrasive dentifrices during at-home bleaching with 10% carbamide peroxide on enamel surface roughness.

During tooth bleaching abrasive dentifrices might change the outer superficial enamel. The aim of this in vitro study was to evaluate the roughness of human enamel exposed to a 10% carbamide peroxide bleaching agent at different times and submitted to different superficial cleaning treatments. The study consisted of 60 sound human enamel slabs, randomly assigned to different treatment groups: G1--not brushed; G2--brushed with a fluoride abrasive dentifrice; G3--brushed with a non-fluoride abrasive dentifrice; and G4--brushed without a dentifrice. There were 15 enamel slabs per group. Slabs of molar teeth were obtained and sequentially polished with sandpaper and abrasive pastes. A perfilometer was used to obtain the mean of Ra value on the surface of each specimen to initial and experimental times. Bleaching was performed on the enamel surface for six hours daily. After that, each slab received a cleaning surface treatment and was stored in artificial saliva. Analysis of variance (ANOVA) and Tukey's HSD hoc analysis (alpha =0.05) revealed significant differences in roughness values over time for enamel bleached and treated with different superficial cleaning methods. G1 and G4 showed no significant differences in roughness over time, G2 and G3 showed a significant increase in the surface roughness values. This in vitro investigation showed the sole use of 10% carbamide peroxide did not alter the enamel surface roughness, but the cleaning treatments that employed the use of brushing with abrasive dentifrices resulted in a significant increase of enamel surface roughness.

Analysis of Variance↗

PubMed2002

Comparative 3-week clinical tooth-shade evaluation of a novel liquid whitening gel containing 18% carbamide peroxide and a commercially available whitening dentifrice.

A randomized, controlled, examiner-blind, parallel-group clinical trial was performed to compare the tooth-whitening benefits of a novel, nontray, "paint-on" liquid gel containing 18% carbamide peroxide (Colgate Simply White Clear Whitening Gel) to those of a commercially available whitening dentifrice. Efficacy was measured by using Vita shade scores obtained at baseline and after 2 and 3 weeks of product use. Eighty subjects were first balanced according to gender, age, and shade scores into two groups. Half were then randomly assigned to either alpha 3-week routine of tooth-brushing (using a nonwhitening dentifrice) and twice-daily 18% carbamide peroxide gel application or a 3-week routine of twice-daily brushing with the commercially available whitening dentifrice. At the completion of the study, the results showed that subjects' teeth in the liquid whitening gel-treated group exhibited a statistically significant (P < .05) 4.12 mean tooth-shade improvement compared to baseline and exhibited a mean score that was 3.7 units higher than the corresponding mean score of the group assigned to use the whitening dentifrice (statistically significant, P < .05). It can therefore be concluded that the combined use of Colgate Simply White Clear Whitening Gel immediately after brushing with a regular toothpaste is clinically superior at whitening teeth than solely using a clinically proven, commercially available whitening dentifrice.

Adolescent↗

PubMed2006

Thirty-five percent carbamide peroxide application causes in vitro demineralization of enamel.

OBJECTIVES: The objective of this in vitro study was to investigate whether a high concentration 'in-office' bleaching agent affected the mineral content of enamel and dentin. METHODS: A commercially available 35% carbamide peroxide bleaching agent was applied for 2h to sectioned teeth (n=11). Specimens were then immersed in artificial saliva at 37 degrees C for a further 24h to simulate the oral environment. Tomographic images of these sections were obtained (micro-CT 80, Scanco, Switzerland) prior to and post-bleach application. Eight three-dimensional regions of interest (ROI), starting from the enamel surface extending to the dentinoenamel junction, were selected for each section. The hydroxyapatite equivalent mineral concentrations (g/cm(3)) of the ROIs were calculated. Any changes in mineral content as a consequence of the bleaching procedure were calculated in relation to each ROI. RESULTS: There was a significant reduction in the mineral content of enamel specimens post-bleach application extending to a depth of 250microm (paired t-test, p<0.05); this reduction in mineral content was greatest in the ROI's closest to the tooth surface. There was, however, no significant difference in the mineral content of dentin as a consequence of bleaching. SIGNIFICANCE: This in vitro study has shown that significant demineralization of enamel occurred following bleaching with 35% carbamide peroxide. The concept that 'in-office' bleaching is a non-destructive cosmetic procedure should be reconsidered.

Carbamide Peroxide↗

PubMed2005

The effect of carbamide peroxide treatment on metal ion release from dental amalgam.

OBJECTIVES: There is concern that hydrogen peroxide generated by tooth bleaching agents may cause enhanced metal ion release (including mercury) from dental amalgam following contact. The aim of this in vitro study was therefore to investigate the effect of a carbamide peroxide (CP) based tooth bleaching gel on metal ion release from dental amalgam. METHODS: Dental amalgam discs were prepared according to the manufacturers' instructions. These were treated with either a 10% carbamide peroxide (CP) gel or a 0% CP gel for 24h. Discs were carefully wiped with cotton wool before immersion in distilled water (20 ml) for 24h at 37 degrees C. Following immersion, water samples were taken for metal ion release determination (Ag, Cu, Hg and Sn) using inductively coupled plasma mass spectrometry methods. The specimens were further evaluated for surface changes using scanning electron microscopy (SEM) and Talysurf surface roughness measurements. RESULTS: The differences in concentration of metal ions released after treatment with the 10% CP gel and a placebo gel treatment were not statistically significant (p>0.05). For example, mercury release following treatment with the 10% CP gel and the 0% CP gel was found to be 1.17(0.5) and 0.57(0.1)microgcm(-2), respectively. Roughness measurements for samples treated with the 10% CP gel and 0% CP gel were 2.23(0.47) and 1.74(0.16)microm, respectively, again showing no significant difference between groups (p>0.05). SEM images of the amalgam surfaces showed no apparent differences between treatments. SIGNIFICANCE: Treatment with a 10% CP gel did not significantly enhance subsequent metal ion release from dental amalgams compared to a control gel, contradicting previously published studies.

Carbamide Peroxide↗

PubMed2003

Influence of dental biofilm on release of mercury from amalgam exposed to carbamide peroxide.

Tooth bleaching is a popular procedure in modern aesthetic dentistry. Bleaching agents may affect amalgam restorations by altering the release of mercury. The aim of this study was to explore the effect of biofilm-coated amalgam restorations on the release of mercury in the presence of carbamide peroxide. Samples of SDI and Valliant amalgams were submerged for either 14 days or 7 months in buffered KCl after which they were coated with saliva, bacteria, and polysaccharides. The samples were exposed to 10% carbamide peroxide (CP) for 24 h. The amount of mercury released was examined for 120 h. Results showed that most of mercury release occurred within the first 24 h, after which the release rate decreased sharply. After 120 h the release of mercury from the tested samples was minimal and similar to the control group. The presence of biofilm coating on the amalgam samples did not induce the release of mercury but tended to reduce mercury release into the surrounding environment. CP induces the release of mercury from amalgam samples. However, the presence of biofilm did not prevent large amounts of mercury release from amalgam coated with biofilms and exposed to CP. This study indicates that dental biofilm may retard the release of mercury from amalgam restorations.

Biofilms↗

PubMed2004

The efficiency of 10% carbamide peroxide gel on dental enamel.

This study investigated the effect of 10% carbamide peroxide gel on human tooth color, vibrational mode, and mineral loss. The exposed enamels were bleached for two weeks (six hours' bleaching and 18 hours' storage in distilled water per day). Color change was calculated from the CIE L*a*b* color values. Vibrational mode in Fourier transform Raman spectrum and mineral content were also estimated. The bleached enamels showed an apparent color change (deltaE* = 5.35). Within the test period, their whiteness increased linearly as the period increased. A slight decrease in Raman peak at 1068 cm(-1)--compared with the peak at 430 cm(-1)--was observed after bleaching. The total mineral content was decreased from 90.39 to 86.01 after bleaching. Also, the calculated Ca/P ratio decreased from 2.10 to 2.07. However, these changes were negligibly different from the enamels stored in distilled water except for a color change.

Analysis of Variance↗

PubMed1994

The effect of carbamide peroxide bleach on the tensile bond strength of ceramic brackets: an in vitro study.

Recent advances in cosmetic dentistry have led to the development of a variety of new products and techniques including vital bleaching and ceramic brackets. Therefore this study was conducted to see whether the use of an at-home carbamide peroxide bleaching agent before bonding affected the tensile bond strength of a precoated ceramic orthodontic bracket. Sixty extracted human premolar teeth were randomly separated into three groups of 20. Group 1 was a control group that was etched and bonded in the usual manner. Group 2 was immersed in a carbamide peroxide home bleaching agent for 72 hours before pumicing and bonding. Group 3 was also bleached for 72 hours but was immersed in distilled water for 1 week before bonding. The results indicated that recently bleached teeth have significantly reduced bond strength values when compared with both groups 1 and 3. We suggest that if a patient is using a tooth whitening product, that they discontinue its use at least 1 week before the bonding of orthodontic attachments.

Acid Etching, Dental↗

PubMed2003

Effectiveness of treatment with carbamide peroxide and hydrogen peroxide in subjects affected by dental fluorosis: a clinical trial.

Dental fluorosis is an endemic dental health problem around the world; so, it is important to develop clinical alternatives that are non-invasive and inexpensive. In this study, nightguard vital bleaching technique (NVBT), using carbamide and hydrogen peroxide as active agents, has shown itself to be effective in whitening teeth affected by dental fluorosis. Carbamide peroxide at 10 and 20% and hydrogen peroxide at 7.5% showed good clinical effectiveness in improving clinical appearence, but it is important to point out that clinical success is only in cases of class 1 to 3 of the Tooth Surface Index of Fluorosis. When comparing 10 and 20% concentrations of carbamide peroxide, there was no difference in the clinical effectiveness (p > 0.05); but when comparing both concentrations of carbamide peroxide against hydrogen peroxide, results showed that carbamide peroxide was more effective in whitening in cases of dental fluorosis, the difference being statistically significant (p < 0.05). NVBT has two advantages: it is a non-invasive technique and the relationship cost/benefit is excellent; only a few patients reported tenderness or mild tooth sensitivity.

Adolescent↗

PubMed1993

Evaluation of a 10 percent carbamide peroxide gel vital bleaching agent.

A clinical study determined the whitening effect of a 10 percent carbamide peroxide gel on the teeth of 10 subjects. Histological evaluation of the effect of this agent on human tooth pulps and hamster cheek pouch tissues was also undertaken. The gel provided a modest, but unpredictable, whitening of discoloured teeth. A localised mild to moderate inflammatory response was found in some of the pulps of teeth that had been bleached. No soft-tissue changes were observed in the hamster cheek pouches.

Adolescent↗

PubMed2002

Greening of the tooth-amalgam interface during extended 10% carbamide peroxide bleaching of tetracycline-stained teeth: a case report.

UNLABELLED: At-home bleaching with 10% carbamide peroxide in a custom-fitted tray has been shown to have some minor effects on certain brands of amalgam, pertaining to mercury release, but generally, effects on amalgam are not considered clinically significant. However, in this case report, a greening of the tooth structure in certain areas immediately adjacent to amalgam restorations in the maxillary and mandibular first molars occurred during tooth whitening. Other amalgam restorations in mandibular and maxillary second molars in the same mouth did not demonstrate any green discoloration of the teeth. Upon removal of the affected amalgam restorations, recurrent decay was present in the areas of tooth greening but not in other areas adjacent to the restoration. The teeth were restored with posterior composite restorations. Whether the green discoloration was a result of some loss of material from a particular brand of amalgam, indicating leakage, or indicative of original or recurrent tooth decay is unclear in this single-patient situation. Other patients in the same study did not demonstrate this occurrence. Dentists should be ready to replace amalgam restorations should this green discoloration in adjacent tooth structure occur during bleaching, in case decay is present. CLINICAL SIGNIFICANCE: The unusual discoloration cited suggests that amalgam restorations in potentially esthetic areas, including the lingual of anterior teeth, should be replaced prior to bleaching, to avoid the problem of difficult stain removal or translucency allowing restoration visibility following bleaching.

Adult↗

PubMed1994

Salivary pH changes during 10% carbamide peroxide bleaching.

The purpose of this study was to evaluate the effect on salivary pH of a 10% carbamide peroxide solution when used with a custom-fitted guard for bleaching teeth. Baseline pH values were established for unstimulated saliva and on saliva produced while wearing an empty guard. After insertion of a guard half filled with Proxigel, salivary pH measurements were made at 5-minute intervals until the values returned to baseline levels. Mean salivary pH values were 6.81 +/- 0.11 for unstimulated samples and 6.91 +/- 0.18 after insertion of the empty guard. After insertion of the filled guard, there was a statistically insignificant decrease in salivary pH during the first 5 minutes, followed by an increase above baseline at 10 minutes, to a mean peak value of 7.32 +/- 0.27 at 15 minutes. The difference between the baseline values and the mean peak value at 15 minutes was statistically significant. The results of the study indicated that the pH of saliva increased significantly during the first 15 minutes of nightguard vital bleaching and did not significantly drop below baseline in the first 2 hours after insertion with a moderately low-pH solution.

Adult↗