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PubMed1999

Colorimetric assessment of laser and home bleaching techniques.

PURPOSE: This study recorded in vitro color change of three tooth bleaching techniques that included laser-activated hydrogen peroxide and two concentrations of carbamide peroxide. MATERIALS AND METHODS: Forty extracted human central incisors were exposed to argon laser-activated 35% H2O2, 10% carbamide peroxide, or 20% carbamide peroxide. A fourth group (control) did not receive any bleach treatment (n = 10/group). Commission International de l'Eclariage (CIE) L*a*b* coordinates were recorded prior to bleaching (baseline), at 1 week, and at 2 weeks. The color difference (delta E*ab) between baseline and subsequent measurements was calculated. RESULTS: The control group did not demonstrate significant color difference over time (p > .05). The laser group was not statistically different from the control group (p > .01). The color difference of the 10% and 20% carbamide peroxide groups was statistically different from the control group (p < .01). CLINICAL SIGNIFICANCE: Exposure to 20% carbamide peroxide produced the greatest perceivable change in color. The recommended one-time application of laser-activated hydrogen peroxide did not demonstrate any perceivable color change. The clinician should be aware that additional or longer applications may be required.

Carbamide Peroxide↗
PubMed1996

Biological properties of peroxide-containing tooth whiteners.

Peroxides have been used in tooth whitening for more than 100 years. Current peroxide-containing whiteners can be classified into three categories: (1) those containing high concentrations of peroxides for professional use only; (2) materials dispensed by dentists and used by patients at home; and (3) over-the-counter products available directly to consumers for home use. Hydrogen peroxide (H2O2) and carbamide peroxide are the most commonly used active ingredients in these whiteners. Both peroxides have long been used safely in oral health products and are accepted by the US Food and Drug Administration. However, questions have been raised regarding the safety of at-home whiteners because the peroxides appear to constitute a new use. Substantial differences exist in the manner of application between at-home whiteners and oral health products. In addition, tooth whiteners are a mixture of various ingredients; possible interactions may occur because of the active nature of peroxides. Therefore, the safety evidence for peroxide-containing whiteners is considered inadequate. This paper will review the history of using peroxides for tooth whitening, the toxicology of H2O2 and carbamide peroxide, and available information on the safety of whiteners. The rationale and approaches for evaluating biological properties of peroxide containing whiteners are also discussed.

Carbamide Peroxide↗
PubMedDate not supplied

In vitro colorimetric evaluation of the efficacy of various bleaching methods and products.

OBJECTIVE: Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficacy is unknown. The aim of this in vitro study was to evaluate the ability of different bleaching products and protocols to lighten enamel and dentin. METHOD AND MATERIALS: Bovine tooth samples of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thicknesses) were prepared and stained with whole blood and hemolysate before being submitted to 11 different bleaching regimens: home bleaching using 10%, 15%, 16%, or 20% carbamide peroxide, power bleaching using 15% hydrogen peroxide, 30% hydrogen peroxide, or 25% carbamide peroxide with or without light activation, and over-the-counter bleaching strips containing 5.3% hydrogen peroxide. Colorimetric measurements were performed on each sample side, according to the CIE L*a*b* system, before and after staining as well as after each series of 5 bleaching sessions (number of applications varied from 5 to 20 times, according to the bleaching protocol). RESULTS: All products and protocols produced a similar bleaching effect on enamel, while the home bleaching regimen proved largely superior to lighten dentin. CONCLUSION: In-office bleaching techniques proved less efficient than home bleaching for removing stains deposited in dentin.

Analysis of Variance↗
PubMed2004

Effect of different peroxide bleaching regimens and subsequent fluoridation on the hardness of human enamel and dentin.

STATEMENT OF PROBLEM: Bleaching of teeth by "in-office" or "home" bleaching techniques are popular methods of whitening teeth. However, bleaching may reduce the surface hardness of enamel and dentin. PURPOSE: The purpose of this study was to evaluate (1) the effect of different concentrations of 2 "in-office bleaching" and 2 "home bleaching" agents applied for different time periods on the hardness of enamel and dentin and (2) the effect of subsequent immersion in a low-concentration fluoride solution on the hardness of bleached enamel and dentin. MATERIAL AND METHODS: The enamel and dentin of 12 extracted intact human molar teeth were sectioned lengthwise, ground, polished, embedded in acrylic resin and divided into 4 groups each (n=12). An area of approximately 5 x 5 mm of enamel and dentin tested for Knoop hardness number (KHN; kg/mm 2 ) at a load of 100 g for 20 seconds (baseline). The specimens were stored in distilled water for 1 hour and the microhardness testing repeated as a control group. The groups were bleached as follows: Group OX and Group OQ were bleached "in office" with Opalescence Xtra (35% hydrogen peroxide) and Opalescence Quick (35% carbamide peroxide), respectively, for 5, 15, or 35 minutes and retested for KHN at the end of each time period. "Home bleaching" products Opalescence F (15% carbamide peroxide) and Opalescence (10% carbamide peroxide) were applied in 14-hour applications at 24-hour intervals to Groups OF and O, respectively, which were then tested for KHN. Specimens were immersed in 0.05% fluoride solution (Meridol) for 5 minutes and retested for KHN. The hardness values were analyzed by 2-way ANOVA and Scheffe post hoc test (alpha=.05). Comparisons of KHN between each time and the baseline measurement for each group were of interest. RESULTS: Significant decreases in KHN of enamel and dentin were found after bleaching for all test groups, dependent on the accumulated bleaching time. Group OX showed a 25% KHN reduction for enamel and 22% for dentin after 35 minutes bleaching (P < .0001). Group OQ showed a 13% KHN reduction (P < .0001) for enamel and 10% for dentin after 35 minutes (P < .005). Group OF showed a KHN reduction of 14% for enamel (P < .05) and 9% for dentin (P < .0001) after 14 hours bleaching, and Group O showed an 18% reduction in enamel (P < .0001) and 13% in dentin (P < .0001) for the same period. Fluoridation completely restored the softened dental tissues. CONCLUSION: The "in-office" bleaching technique reduced the hardness significantly more than the "home" bleaching technique. Low-concentration fluoride mouth rinse (Meridol) restored the softened dental tissues.

Analysis of Variance↗
PubMed1996

Surface morphology changes in human enamel, dentin and cementum following bleaching: a scanning electron microscopy study.

Extracted human premolars were cut, cleaned and divided into 6 experimental groups. Each group was treated with one of the following bleaching materials: 30% hydrogen peroxide, 10% carbamide peroxide, sodium perborate, Nu-Smile, Opalescence and DentlBright. Morphological changes in tooth surface occurred following treatment with most bleaching agents. Hydrogen peroxide and DentlBright were associated with surface changes in all dental tissues. Hydrogen peroxide, DentlBright, Nu-Smile and Opalescence were mainly associated with surface changes in the cementum, which exhibited more changes than the other tissues.

Borates↗
PubMed2002

Overview of a professional tooth-whitening system containing 6.5% hydrogen peroxide whitening strips.

Professionally dispensed, at-home tooth whitening began with 10% carbamide peroxide gels applied to the dentition with custom-made trays. In the 1990s, higher-concentration carbamide peroxide gels were introduced to achieve faster results. Today, 15% and 20% carbamide peroxide gels are commonly used. Recently, a new vital tooth-whitening technique that uses a flexible strip rather than a tray to apply a 5.3% hydrogen peroxide whitening gel was introduced. The new strip-based product was shown to provide whitening equivalent to a 10% carbamide peroxide tray with half the wear time. In addition, the strip eliminated the need to custom fabricate trays for each patient. This article provides an overview of a professionally distributed strip-based whitening system and reviews some of the clinical data which supports the efficacy of the product. This new whitening system includes 42 mandibular and 42 maxillary strips at a higher concentration of 6.5% hydrogen peroxide. In addition, the system also includes a novel dual-action whitening dentifrice to prevent future staining postbleaching and an extrasoft toothbrush. Clinically, the professionally distributed strip-based whitening system provided 96% more efficacy than a popular carbamide plus hydrogen peroxide (equivalent to 10% carbamide peroxide) tray system and 52% more whitening than the 5.3% hydrogen peroxide strip system.

Carbamide Peroxide↗
PubMed1992

Catalase/peroxidase activity in dental pulp.

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

Catalase↗
PubMed2004

Clinical response of three whitening products having different peroxide delivery: comparison of tray, paint-on gel, and dentifrice.

OBJECTIVE: Comparative clinical research was conducted to evaluate the efficacy and safety of three peroxide-containing tooth whitening products having different peroxide delivery. METHODOLOGY: A total of 43 healthy adults who met entrance criteria were randomly assigned to either a dual-phase, anticavity, 1% hydrogen peroxide dentifrice with a manganese gluconate activator, an 18% carbamide peroxide paint-on gel, or a 5% carbamide peroxide professional custom tray system. Following manufacturer's instructions, the activated dentifrice was used at least twice daily for two minutes, while the paint-on gel was applied twice daily. The custom tray, a barrier system and the experimental control for this study, was worn continuously for six to eight hours daily. Tooth color (L*a*b*) was measured on the maxillary anterior teeth from standard digital images, while safety was assessed from examination and subject report. RESULTS: At Day 15, the custom tray group had a significant (p < 0.002) reduction in yellowness and increased lightness, with adjusted mean (SE) deltab* of -1.83 (0.210) and deltaL* of 1.45 (0.292). The custom tray group experienced on average greater color improvement compared to either the paint-on gel or activated peroxide whitening dentifrice, differing significantly (p < 0.01) from either of the barrier-free systems with respect to deltab*, deltaL*, deltaE*, and deltaW*. In comparison, 14-days' use of the paint-on gel and activated dentifrice did not result in significant (p > 0.10) color improvements from baseline for deltab*, deltaL*, or deltaW*, with these two barrier-free systems not differing significantly (p > 0.26) with respect to any individual or composite color parameters. Tooth sensitivity and oral irritation were the most common safety findings in the tray and dentifrice groups (there were no adverse events in the paint-on group), and no subject discontinued treatment early because of a treatment-related adverse event. CONCLUSION: In head-to-head 14-day testing, a low concentration (5% carbamide peroxide) barrier-based tray system yielded superior tooth color improvement compared to two barrier-free delivery systems-an 18% carbamide peroxide paint-on gel and a 1% hydrogen peroxide dentifrice with a metal activator.

Adolescent↗
PubMed2002

Tooth whitening in children.

Although there are several case reports of vital tooth bleaching in children, there is limited clinical trial evidence of the safety or efficacy of this practice. Accordingly, a new clinical trial was conducted to evaluate the effects of 2 different bleaching systems, a 6.5% hydrogen peroxide strip system and a 10% carbamide peroxide tray system, in a population of preteens and teens. A total of 106 volunteers, aged 11 to 18 years, took part in this 8-week study. Patients were randomized by a ratio of 2:1 to the strip or tray groups, with each group treating the maxillary arch first and then the mandibular arch for 4 consecutive weeks each. Individuals assigned to the strip group used the system twice daily for 30 minutes (a total of 56 contact hours over the 8-week study). Those assigned to the tray group used that system overnight (approximately 448 contact hours). Digital images were obtained at baseline and after every 2-week treatment period. Average tooth color was determined in L*, a*, b* color space, where L* indicated lightness, a* indicated red-green, and b* indicated yellow-blue. Both systems significantly whitened teeth (P < 0.0001). While there were no significant differences between groups with respect to the primary whitening response (delta b*) on the maxillary teeth, 4 weeks of overnight treatment with the 10% carbamide peroxide tray (approximately 224 contact hours) yielded statistically significant whitening (P < 0.05) on the mandibular teeth compared with the 6.5% hydrogen peroxide strip used for 28 hours. Both tooth-whitening systems had similar sensitivity/irritation reported after instructed use. This research demonstrates that tooth whitening in teens may be safely accomplished using either the short-contact-time hydrogen peroxide bleaching strips or the overnight carbamide peroxide tray systems tested in this study.

Adolescent↗
PubMed2004

Effect of traditional and alternative intracoronal bleaching agents on microhardness of human dentine.

The purpose of this study was to compare the effect of traditional and alternative bleaching agents on microhardness of human dentine when used intracoronally. Thirty-six premolars were divided into six groups and bleaching agents were sealed into the pulp chambers as follows: group 1--distilled water (control), group 2--30% hydrogen peroxide solution, group 3--sodium perborate mixed with distilled water, group 4--sodium perborate mixed with 30% hydrogen peroxide solution, group 5--35% carbamide peroxide gel, group 6--35% hydrogen peroxide gel. Access cavities were sealed and the teeth were stored in distilled water at 37 degrees C. After 7 days, each tooth was sectioned at the cemento-enamel junction level and microhardness testing was carried out on dentine. The results showed that treatment with 35% hydrogen peroxide gel, 30% hydrogen peroxide solution and 35% carbamide peroxide gel reduced the microhardness of outer dentine to a small extent while treatment with sodium perborate mixed with water and sodium perborate mixed with 30% hydrogen peroxide solution did not significantly alter the microhardness of dentine.

Antioxidants↗
PubMed2004

Extraradicular diffusion of hydrogen peroxide and pH changes associated with intracoronal bleaching of discoloured teeth using different bleaching agents.

AIM: To evaluate the extraradicular pH and hydrogen peroxide (HP) diffusion when either 35% carbamide peroxide (CP), 35% HP or sodium perborate (SP) is used for intracoronal bleaching of artificially discoloured teeth. METHODOLOGY: Single rooted extracted human premolars were stained with whole blood cells. After shaping and cleaning, they were root filled and a base cement placed 1 mm below the buccal cementoenamel junction (CEJ). Four cemental defects were prepared just below the CEJ on each root surface. The teeth were randomly divided into four groups of 11 specimens, and intracoronally bleached using CP, HP, SP or distilled water (CL). Each tooth was suspended in a vial of distilled water and bleached for 7 days. The pH of the extraradicular distilled water was tested at 0, 1, 2 and 7 days and the HP that diffused through the root quantified using the Ferrous Oxidation-Xylenol Orange 2 Assay. The results were analysed using the one-way anova and Scheffe tests. RESULTS: Carbamide peroxide produced the greatest increase and HP the least pH change (P < 0.05 except day 1), SP was intermediate. From day 1 onwards, radicular diffusion of HP was greatest with HP and least with CP (P < 0.01), again SP was intermediate. There was no significant difference between CP and SP. CONCLUSIONS: Carbamide peroxide had very low levels of extraradicular diffusion of HP, in the presence of cemental defects. It could be an alternative to the other intracoronal bleaching agents.

Adolescent↗
PubMed2003

Tooth bleaching--a critical review of the biological aspects.

Present tooth-bleaching techniques are based upon hydrogen peroxide as the active agent. It is applied directly, or produced in a chemical reaction from sodium perborate or carbamide peroxide. More than 90% immediate success has been reported for intracoronal bleaching of non-vital teeth, and in the period of 1-8 years' observation time, from 10 to 40% of the initially successfully treated teeth needed re-treatment. Cervical root resorption is a possible consequence of internal bleaching and is more frequently observed in teeth treated with the thermo-catalytic procedure. When the external tooth-bleaching technique is used, the first subjective change in tooth color may be observed after 2-4 nights of tooth bleaching, and more than 90% satisfactory results have been reported. Tooth sensitivity is a common side-effect of external tooth bleaching observed in 15%-78% of the patients, but clinical studies addressing the risk of other adverse effects are lacking. Direct contact with hydrogen peroxide induced genotoxic effects in bacteria and cultured cells, whereas the effect was reduced or abolished in the presence of metabolizing enzymes. Several tumor-promoting studies, including the hamster cheek pouch model, indicated that hydrogen peroxide might act as a promoter. Multiple exposures of hydrogen peroxide have resulted in localized effects on the gastric mucosa, decreased food consumption, reduced weight gain, and blood chemistry changes in mice and rats. Our risk assessment revealed that a sufficient safety level was not reached in certain clinical situations of external tooth bleaching, such as bleaching one tooth arch with 35% carbamide peroxide, using several applications per day of 22% carbamide peroxide, and bleaching both arches simultaneously with 22% carbamide peroxide. The recommendation is to avoid using concentrations higher than 10% carbamide peroxide when one performs external bleaching. We advocate a selective use of external tooth bleaching based on high ethical standards and professional judgment.

Animals↗
PubMed2001

Experimental study to test the potential tumor promotion effect of a tooth bleaching agent.

Carbamide Peroxide is routinely employed as a whitener for tooth enamel. Oral mucosa protection is recommended to avoid inflammatory reactions. Experimental work has demonstrated its irritative effect on gastric mucosa when swallowed. The activity of certain oxidizing agents as tumoral promoters has been demonstrated and associated to their capacity to induce hyperplasia. Within this context it seemed of interest to assess the possible action of carbamide peroxide as a tumoral promoter in oral mucosa with or without a precancerous condition. Its action was tested in 2 models which are highly sensitive to chemical cancerization: a) Dorsum skin or SENCAR mice treated with carbamide peroxide daily or twice a week with or without prior initiation with dimethylbenz(a)anthracene (DMBA). Control mice were submitted to the standard carcinogenesis protocol, i.e. initiation with DMBA and promotion with 12-O-tetradecanoyl phorbol acetate (TPA). b) Hamster cheek pouch submitted to topical application of carbamide peroxide 3 times a week with or without prior initiation with DMBA, hamster cheek pouch submitted to repeated topical application of DMBA as a complete carcinogen: application twice a week in the control group and identical treatment + 1 weekly application of carbamide peroxide to evaluate its capacity to enhance the process. The effects were assessed between 1 and 14 weeks of treatment at different intervals for the different experimental protocols. The control cases exhibited hyperplasia and tumor induction in keeping with the known sequence for both carcinogenesis models. None of the cases revealed a promoter or enhancer capacity of carbamide peroxide. These results indicate the lack of risk involved in the application of carbamide peroxide even in oral mucosa with a precancerous condition due to the action of initiation agents such as tobacco and alcohol.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2003

Clinical response of three direct-to-consumer whitening products: strips, paint-on gel, and dentifrice.

A randomized, examiner-blind, parallel-group, 3-week clinical trial evaluated the efficacy and safety of 3, popular, direct-to-consumer whitening products: a paint-on gel, a whitening dentifrice, and whitening strips. Both the paint-on gel (18% carbamide peroxide) and the whitening strips (6% hydrogen peroxide) were peroxide-based systems, while the dual-phase whitening dentifrice incorporated surface cleaning agents and sodium fluoride, but contained no peroxide. Treatment consisted of twice-daily use over 3 weeks following label instructions, except that strips were applied only during the first 14 days as per the manufacturer's instructions. Tooth color was measured on the maxillary anterior teeth from polarized digital images. Safety was assessed by examination and subject report. A total of 48 healthy adults were randomized, and 42 completed 1 or more post-baseline visits. For the primary efficacy variable delta b*, the adjusted mean +/- standard error reduction in yellowness was -0.06 +/- 0.131 for the dentifrice with no peroxide and -0.21 +/- 0.109 for the 18% carbamide peroxide paint-on gel, compared with -2.53 +/- 0.244 for the whitening strip control. Only the strip group exhibited significant (P < 0.0001) delta b* improvement. Between-group comparisons demonstrated significant and improved whitening for the strip treatment compared with the whitening dentifrice or paint-on peroxide gel, as evidenced by the more than 2-unit improvement in delta b* at week 3. Regardless of the parameter (delta b*, delta L*, delta a*, or delta E*), this represented a significant (P < 0.0001) color improvement for the whitening strips relative to both of the comparative treatments. There were no significant differences in color improvement for the 18% carbamide peroxide paint-on gel used for up to 3 weeks continuously, compared with normal brushing with a dual-phase whitening dentifrice. All products were well tolerated, with no subjects discontinuing treatment early because of adverse events. In head-to-head testing conditions, 14-day use of the 6% hydrogen peroxide whitening strips resulted in superior improvement in tooth color compared with either of the experimental controls.

Adult↗
PubMed2003

The effect of current bleaching agents on the color of light-polymerized composites in vitro.

STATEMENT OF PROBLEM: Bleaching agents may affect the color of existing composite restorations. PURPOSE: The purpose of this study was to compare the effect of 10% carbamide peroxide and 10% hydrogen peroxide on the color of light-polymerized hybrid, macrofilled, and polyacid-modified composites. MATERIAL AND METHODS: Two light-polymerized hybrid composites (3M Valux and Spectrum TPH), 1 macrofilled condensable composite (Solitaire), and 2 polyacid-modified composites (Dyract AP and Compoglass) were used. The hybrid composites served as controls. The color of 8 specimens of each material was analyzed by use of a spectrophotometer before bleaching. The specimens were then divided randomly into 2 subgroups (n=4). One group was immersed in 10% carbamide peroxide solution and the other in 10% hydrogen peroxide, for 8 hours each for 14 consecutive days. After bleaching, color changes (Delta E) were determined for each material and compared by use of the Kruskal-Wallis test, followed by the Mann-Whitney U test (P<.05). RESULTS: After bleaching with carbamide peroxide, the color changes (Delta E) for Dyract AP (2.18; SD = 1.41), Compoglass (1.14; SD = 0.26) and Solitaire (1.56; SD = 0.89) were higher than the color changes recorded for 3M Valux (0.63; SD = 3.60), and Spectrum TPH (0.66; SD = 1.24). The differences between materials bleached with carbamide peroxide were not statistically significant. After bleaching with hydrogen peroxide, the color changes for Dyract AP (9.39; SD = 0.53) and Compoglass (5.15; SD = 0.52) were higher than the changes recorded for Spectrum TPH (4.53; SD = 1.53) and 3M Valux (3.41; SD = 4.40), whereas the color change of Solitaire (3.69; SD = 0.57) was significantly higher than that of 3M Valux (P=.01). The color changes for all restorative materials tested were clinically detectable after the application of 10% hydrogen peroxide. However, clinically noticeable discoloration was observed only for Dyract AP treated with 10% carbamide peroxide. CONCLUSION: In comparison to 10% carbamide peroxide, 10% hydrogen peroxide caused more color changes in the composites tested.

Carbamide Peroxide↗
PubMed2004

Effects of hydrogen peroxide bleaching strip gels on dental restorative materials in vitro: surface microhardness and surface morphology.

OBJECTIVE: This study examined the effects of peroxide tooth bleaching, including Crest Whitestrips hydrogen peroxide gel treatments, on the surface hardness and morphology of common dental restorative treatments. METHODOLOGY: American Dental Association (ADA) recommended dental restorative materials, including amalgam, dental gold, porcelain, glass ionomer, and composites, were prepared according to manufacturers' instructions. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching gels, which utilize hydrogen peroxide as the in situ bleaching source, and several commercial carbamide peroxide bleaching gels. Control treatments included placebo gels and an untreated group. Crest Whitestrips bleaching included treatment exposures simulating recommended clinical exposures (14 hours), along with excess bleaching simulating exposure to five times suggested Crest Whitestrips use. At the conclusion of treatments, surface microhardness measures and surface morphological assessments with standard and variable pressure (VP-) SEMs were conducted to assess the effects of bleaching exposure on the surface morphology and structural integrity of the restoratives. RESULTS: Surface microhardness and SEM measures revealed no significant deleterious effects on the restoration surfaces from Whitestrips gels. CONCLUSION: These results confirm that tooth bleaching from the selected commercial hydrogen peroxide or carbamide peroxide bleaching systems does not produce changes in surface morphology or microhardness of common dental restorative materials. These results support the clinical safety of the selected commercial bleaching systems to the oral environment, matching results obtained from long-term use of these ingredients applied in dental offices and available in commercial formulations.

Carbamide Peroxide↗
PubMed2003

Effects of Crest Whitestrips bleaching on surface morphology and fracture susceptibility of teeth in vitro.

OBJECTIVE: This study examined the effects of peroxide tooth bleaching, including Crest Whitestrips hydrogen peroxide treatments, on the fracture susceptibility and surface morphology of human tooth enamel in vitro. METHODOLOGY: Extracted human molars were ground and polished to prepare a uniform substrate for bleaching treatments. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching gels, which utilize hydrogen peroxide as the in situ bleaching source, and several commercial carbamide peroxide bleaching gels. Control treatments included placebo gels and an untreated group. Crest Whitestrips bleaching included treatment exposures simulating recommended clinical exposures (14 hours of bleaching), along with excess bleaching simulating exposure to five times the suggested Crest Whitestrips use. At the conclusion of treatments, surface color measurements were taken to ensure tooth bleaching. Surface microhardness measures and surface morphological assessments with SEM were conducted to assess the effects of bleaching exposure on the surface morphology and mineral integrity of the teeth. These latter measures were then complemented with assessments of fracture susceptibility utilizing detailed analyses of crack propagation resulting from post-treatment microhardness indentations. RESULTS: Surface microhardness and SEM measures revealed no deleterious effects on the enamel surfaces from any of the bleaching products assessed. This included conditions of excess bleaching exposure or "overbleaching." The analysis of fracture susceptibility similarly revealed no significant effects from tooth bleaching, regardless of the peroxide source. CONCLUSIONS: These results confirm that tooth bleaching from the selected commercial hydrogen peroxide or carbamide peroxide bleaching systems do not produce changes in surface morphology, microhardness or fracture susceptibility of human tooth enamel under in vitro cycling conditions of treatment matching clinical bleaching exposures. These results support the clinical safety of the selected commercial bleaching systems to vital dentition, matching results obtained from the long-term use of these ingredients applied in dental offices and available in commercial formulations.

Analysis of Variance↗
PubMed2003

Clinical response of two brush-applied peroxide whitening systems.

OBJECTIVE: A randomized, examiner-blind parallel design study was conducted to evaluate the clinical efficacy and tolerability of two brush-applied, peroxide-based tooth whiteners. METHODOLOGY: A total of 38 subjects were randomized to Colgate Simply White, an 18% carbamide peroxide paint-on liquid in an applicator bottle, or Crest Night Effects, a 19% sodium percarbonate system in unit dose sachets that dries to form an adherent film. Treatment was for 14 days. The 18% carbamide peroxide gel was applied twice daily, while the 19% sodium percarbonate film was applied for overnight use. Subjects were evaluated at baseline, and again after 7 and 14 days of treatment using digital images to assess tooth color, and oral examinations to establish safety. Whitening efficacy was determined by evaluating the reduction in tooth yellowness (delta b*), increase in tooth brightness (delta L*), reduction in tooth redness (delta a*) and overall tooth color change relative to pure white (delta W*). RESULTS: After 14 days, the mean change in yellowness (delta b*) was -1.43 +/- 0.20 for the 19% sodium percarbonate film, and -0.44 +/- 0.06 for the 18% carbamide peroxide gel. Mean change in brightness (delta L*) was 1.13 +/- 0.13 and 0.55 +/- 0.13 in the film and gel groups, respectively. Between-group comparisons showed highly significant (p < or = 0.003) whitening for the 19% sodium percarbonate film compared to the 18% carbamide peroxide gel for all 14-day color measurements (delta b*, delta L*, delta a* or delta W). Both products were well-tolerated, with no subjects discontinuing treatment early due to a causal adverse event. CONCLUSION: In a direct clinical comparison of two brush-applied products over 14 days, Crest Night Effects provided significant and meaningful improvement in tooth color, representing more than double the whitening measured for the Colgate Simply White.

Adolescent↗