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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↗

Evaluating tooth color change from carbamide peroxide gel.

A double-blind experiment assessed the efficacy, longevity and safety of a tooth whitener in young adults. Significant color changes occurred after active treatment but were substantially reversed after one week. No permanent changes were found in either pulpal or gingival health.

Adult↗

Effects of carbamide peroxide containing bleaching agents on the morphology and subsurface hardness of enamel.

The purpose of this study is to evaluate the effects of nightguard bleaching agents (Karisma and Yotuel) on the enamel surface of forty anterior teeth. Ten teeth of each group were evaluated with SEM and ten teeth of each group were tested with a microhardness tester Morphologic alterations were observed on the enamel surfaces with SEM. Karisma group showed a significant decrease in enamel hardness (p<0.05) and microhardness values of enamel were increased significantly in Yotuel group (p<0.05).

Carbamide Peroxide↗

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↗

Clinical evaluation of a new 10% carbamide peroxide tooth-whitening agent.

NUPRO Gold Tooth Whitening System was evaluated for efficacy according to the proposed ADA guidelines for acceptance. Sixty participants with discolored anterior teeth participated in a 14-day, double-blind, clinical trial. The participants were matched for age, gender, and oral health status and were given either a placebo gel without the active agent or the NUPRO Gold active gel, which they wore in a custom-fabricated mouth guard for home use. The shade of each participant's maxillary anterior teeth was evaluated using a value-oriented Vita Lumin Vacuum Shade Guide before the study. The same shade guide was used to determine shade changes. Time of use of the agent and potential side effects, such as tooth and gingival hypersensitivity and tissue irritation, were assessed at all recall examinations and were recorded by participants in daily diaries. The average shade change for the placebo users was less than one shade. The average shade change for the NUPRO Gold users was 6.96 shades. Tooth hypersensitivity varied from none to severe. Tissue irritation was minimal. The results of these evaluations indicate that NUPRO Gold is effective as a tooth-whitening system, when administered properly under the supervision of a dentist, with commonly reported side effects of transient tooth sensitivity and minimal gingival sensitivity. Little or no change in tissue health was noted. This study was supported by Dentsply Preventive Care (York, Pennsylvania).

Adolescent↗

Effects of carbamide peroxides on wear resistance and color change of enamel opposing porcelain.

PURPOSE: This study evaluated the effects of a simulated 1- and 2-week night guard bleaching technique using various bleaching gel concentrations on wear resistance and color change of human enamel opposing a feldspathic porcelain substrate. MATERIALS AND METHODS: VMK 68 feldspathic porcelain was formed into 15-mm disks (n = 63) and fired according to manufacturer's recommendations. Enamel cusps were formed and shaped from extracted third molars and treated with 1 of 3 bleaching materials for 7 or 14 days. Specimens were kept at 37 degrees C in 100% humidity. The control group was subjected to identical conditions but with water replacing the bleaching gel between and during bleaching treatments. After simulated bleaching, the enamel cusp specimens were subjected to 3-body wear testing opposite a highly polished porcelain substrate. Enamel wear was evaluated using optical scanning methods, and color was measured with a small-aperture colorimeter. Data were subjected to a one-way repeated- measure analysis of variance and various post hoc statistics. RESULTS: Results indicated that the within effect of treatment time (7 or 14 days) did not significantly affect (p = 0.13) the size of the resulting enamel wear facet, whereas the between effect of bleaching concentration was significant (p = 0.01). Statistical analysis of unbleached control groups suggests that between-group differences can be explained by variations in wear rates of the 3 enamel groups, not by the concentration differences in bleaching gels. All bleaching treatments resulted in significant color changes (p = 0.04) compared to the unbleached control, but the bleach concentration did not significantly influence the magnitude of color change (p = 0.81). CONCLUSIONS: A simulated night guard vital bleaching treatment of 1 or 2 weeks had no significant effect on the wear resistance of human enamel in vitro. The increased bleaching treatment time and concentration did not significantly affect the amount of enamel color change.

Aluminum Silicates↗

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↗

Flexural strength and modulus properties of carbamide peroxide-treated bovine dentin.

BACKGROUND: The effects of carbamide peroxide bleach on tooth structure are uncertain. PURPOSE: The purpose of this study was to investigate the effects of direct or indirect carbamide peroxide application on dentin flexural strength and modulus in vitro. MATERIALS AND METHODS: Dentin bars were machined from bovine incisors and treated with 10% carbamide peroxide for 6 h/d for 14 days. Four groups were created, with eight bars in each group: group 1-direct bleach application only; group 2-indirect bleach application only; group 3-direct bleach application followed by a 2-week storage in artificial saliva; group 4-direct bleach application followed by a 2-week storage in artificial saliva and daily topical fluoride treatments. The specimens' flexural strength and modulus were tested after 24 hours, and the results were compared with water controls using independent t-tests (p < .05). RESULTS: Flexural strength results (in megapascals) for bleached versus control dentin (1=205+/-26 vs 215+/-14, 2=257+/-25 vs 261+/-14, 3=180+/-22 vs 193+/-36, 4=157+/-18 vs 184+/-11) were significantly lower in group 4 (p=.005). Modulus results (in gigapascals) for bleached versus control dentin (1=10.7+/-1.4 vs 12.2+/-0.6, 2=14.2+/-1.7 vs 14.4+/-1.6, 3=10.0+/-2.0 vs 10.9+/-1.3, 4=9.0+/-1.2 vs 11.1+/-1.0) were significantly lower in groups 1 and 4 (p=.013 and p=.003, respectively). There were no significant differences in strength and modulus results between the bleached and control dentin in groups 2 and 3. A direct application of carbamide peroxide to bovine dentin significantly decreased some dentin mechanical properties in vitro. An indirect application of carbamide peroxide to dentin did not significantly decrease dentin strength and stiffness. CLINICAL SIGNIFICANCE: This in vitro study suggests that a bleaching treatment, when applied to the enamel of intact teeth, does not significantly affect the mechanical properties of the underlying dentin. However, when applied directly to dentin in clinical situations such as root exposure or occlusal attrition, the bleaching treatment may result in altered mechanical properties of dentin. The clinical consequences of this observation are, however, unknown.

Animals↗

Ultra-morphological study of the interaction of dental adhesives with carbamide peroxide-bleached enamel.

PURPOSE: To evaluate the effects of a carbamide peroxide bleaching agent on interfaces formed by two one-bottle dental adhesives to etched enamel. The null hypotheses tested in this study were that vital bleaching with a commercial 10% carbamide peroxide gel would not (1) increase the concentration of oxygen in the superficial layer of enamel or (2) induce ultra-morphological changes in resin-enamel interfaces. MATERIALS AND METHODS: Five extracted human incisors were treated with 10% carbamide peroxide (Opalescence) for 4 h/day for 1 week and were compared with non-bleached teeth for oxygen, calcium, and phosphorus relative concentration using EDS. Mean elemental concentrations were analyzed using a t-test (bleached vs. unbleached enamel), one-way ANOVA (for surface location and also for depth) and three-way ANOVA (with bleaching treatment, surface location, and depth as the main factors). For TEM, fifteen extracted human molars were sectioned to obtain two crown halves. After roughening the occlusal surface, one half was bleached with Opalescence while the other half was stored in artificial saliva for 1 week. Enamel was etched for 15 s with a 35% phosphoric acid and bonded with one of three adhesives (Prime & Bond 2.1, Syntac Single-Component, or Scotchbond Multi-Purpose Adhesive-control) and a composite resin (Protect Liner F). Small enamel/resin sticks with a cross-section of 1.0 mm x 1.0 mm were removed and the specimens were processed for TEM observation. RESULTS: Vital bleaching with 10% carbamide peroxide caused no significant changes in relative oxygen concentration of enamel. For calcium and phosphorus, bleaching resulted in significant decreased relative concentrations. Bleaching also resulted in morphological alterations in the most superficial enamel crystallites. Some altered crystallites exhibited electron-lucent cores and reduced thickness of material around the core.

Acid Etching, Dental↗

Use of hydrogen peroxide-based tooth whitening products and its relationship to oral cancer.

UNLABELLED: Tooth whitening products containing hydrogen peroxide or carbamide peroxide were evaluated in this review for potential oral cancer risk from their use. Hydrogen peroxide is genotoxic in vitro, but not in vivo. Hydrogen peroxide was not considered to pose a genotoxic risk to humans. The animal toxicology data relevant to the assessment of the carcinogenicity of hydrogen peroxide do not indicate that it has significant carcinogenic activity at any site, including the oral cavity. Hydrogen peroxide was found to enhance the carcinogenic effects of potent DNA reactive carcinogens in experimental animals. However, these experimental conditions are artificial as they are related to high exposures and are of no relevance to potential human exposures to low quantities of hydrogen peroxide from the use of tooth whitening products. Clinical data on hydrogen peroxide-containing tooth whitening products show no evidence for the development of preneoplastic or neoplastic oral lesions. Exposures to hydrogen peroxide received by the oral cavity are exceedingly low, of short duration (30-60 minutes), and could not plausibly enhance any carcinogenic risk associated with exposure of the oral cavity to chemicals in cigarette smoke or to alcohol, both known risk factors for the development of oral cancer. CLINICAL SIGNIFICANCE: Based on a comprehensive review of the available literature and research, the use of tooth whitening products containing hydrogen peroxide or carbamide peroxide does not appear to pose an increased risk of oral cancer in the general population, including those persons who are alcohol abusers and/or heavy cigarette smokers.

Journal Article↗

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↗

The effect of different bleaching agents on the surface texture of restorative materials.

This blind in vitro study evaluated the effect of a home and an in-office bleaching agent on the surface texture of different tooth-colored restorative materials. Four composites (a hybrid, a flowable, a microhybrid and a nano-hybrid), an ormocer and a ceramic were used, and 2 bleaching agents were tested: 38% hydrogen peroxide and 15% carbamide peroxide. For 38% hydrogen peroxide, the surface morphology of the restorative materials was evaluated after the following time periods: before bleaching, after 15, 30 and 45 minutes of bleaching, 24 hours and 1 month after bleaching. For 15% carbamide peroxide, the time periods were: before bleaching, after 8 and 56 hours of bleaching and 24 hours and 1 month after bleaching. For the 4 composite materials and the ormocer, 2 samples groups were prepared; in 1 group, the specimens were polished and in the other, they stayed unpolished. For the ceramic group, polished samples were prepared. For every material, 3 samples per category and time period were prepared, respectively. Subsequently, the appropriate bleaching procedure was performed on samples of every group. Scanning electron micrographs were produced at 60x, 200x and 2000x magnifications of respective areas of the samples. The results showed that the effect of bleaching on the surface texture was material- and time-dependent. Within the limitations of this study, it was concluded that bleaching with 38% hydrogen peroxide and 15% carbamide peroxide did not cause major surface texture changes on the polished surfaces of the restorative materials.

Carbamide Peroxide↗

Effect of internal bleaching agents on dentinal permeability of non-vital teeth: quantitative assessment.

The aim of this in vitro study was to assess quantitatively dentin permeability of pulpless teeth after intracoronal bleaching therapy with three different agents. Twenty-four maxillary central incisors were randomly assigned to four groups according to the bleaching agent used: I--non-bleached control; II--37% carbamide peroxide; III--sodium perborate/20% hydrogen peroxide paste; IV--27% carbamide peroxide. After standard access and root-canal preparation the access opening, biomechanical preparation and root-canal filling, a cervical glass ionomer plug was prepared and intracoronal bleaching procedures were carried out in a standardized fashion. The access cavities were opened and the teeth were externally sealed and immersed in a 10% copper sulfate aqueous solution for 30 min, in vacuum for the first 5 min. Then, samples were removed, dried with absorbing paper and immersed in a 1% rubianic acid alcohol solution, for the same above-mentioned period in solution and in vacuum. Copper ion penetration was indicated by the rubianic acid staining. Mean values and SD for the experimental groups were: I--7.88% (+/-1.33), II--16.94% (+/-5.72); III--11.45% (+/-3.90) and IV--8.98% (+/-4.19). Data were submitted to one-way anova. The results showed that the 37% carbamide peroxide provided the highest increase in dentin permeability, followed by sodium perborate with 20% hydrogen peroxide. The 27% carbamide peroxide provided the lowest results and showed statistical similarity to the control group. On basis of these findings, it may be concluded that, among the tested intracoronal bleaching agents, 37% carbamide peroxide presented an optimized overall performance in increasing dentinal permeability.

Analysis of Variance↗

Immediate bonding to bleached enamel.

This research sought to determine the shear bond strength, degree of resin infiltration and failure mode when organic solvent-based adhesives (acetone or ethanol) were used in immediate bonding to enamel bleached with 10% carbamide peroxide or 38% hydrogen peroxide systems. Seventy-two non-carious bovine incisors were randomly assigned to three groups of 24 specimens each-control group (deionized water), 38% hydrogen peroxide bleach group and 10% carbamide peroxide bleach group. Each group was further subdivided into two subgroups of 12 specimens each according to the adhesive system used to bond the resin composite to enamel surfaces. The two adhesive systems used were Single Bond, an ethanol-based adhesive, and One Step, an acetone-based adhesive. The shear bond strengths of 38% hydrogen peroxide and 10% carbamide peroxide were significantly lower compared to the non-bleached controls. Fractography revealed an adhesive failure mode in all specimens. Qualitative comparisons of resin tags present in the bleached and unbleached specimens using scanning electron microscopy (SEM) revealed few, thin and fragmented resin tags when 38% hydrogen peroxide and 10% carbamide peroxide were used.

Acetone↗

The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.

This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P <0.05) for Nite-White and Opalescence. All the bleaching agents decreased the microhardness of the porcelain and increased that of the light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

Aluminum Silicates↗

Influence of carbamide peroxide-based bleaching agents on the bond strength of resin-enamel/dentin interfaces.

In this bond strength study, a bleaching agent containing 10% carbamide peroxide was applied over composite-teeth bonded interfaces of two adhesive systems applied to enamel and dentin. Sixteen human third molars were used for bonding procedures. Single Bond (SB) and Clearfil SE Bond (CB) were applied to enamel and dentin according to the manufacturers' instructions. A resin composite cube-like structure was incrementally built on the bonded surfaces. The restored teeth were sectioned into 0.7 mm thick slices that were trimmed at enamel or dentin bonded interfaces to an hourglass shape with a cross-sectional area of approximately 0.5 mm2. Specimens were assigned to 8 groups (n = 10) according to the following factors under study: dental substrate (enamel and dentin); adhesive system (SB and CB) and treatment (10% carbamide peroxide and not bleached/control). The bleaching gel (Opalescence) was applied at the bonded interfaces for 6 hours during 14 days and after daily treatment specimens were stored in artificial saliva. Unbleached specimens were stored in artificial saliva for 14 days. Specimens were tested for tension and the data were analyzed by three-way ANOVA and Tukey's test (p < 0.05). Enamel tensile bond strength of CB was reduced after carbamide peroxide application. The bleaching treatment did not alter dentin bond strength of both adhesives. The results suggest that bleaching significantly affects bond strength of CB to enamel, but no influence on bond strength to dentin was noted for both adhesive systems.

Analysis of Variance↗