Safety Assessment of Hydrogen Peroxide as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Hydrogen Peroxide for use in cosmetics. This ingredient is reported to function in cosmetics as an antimicrobial agent, cosmetic biocide, oral health care agent, and oxidizing agent. The Panel reviewed the data relevant to the safety of this ingredient and concluded that Hydrogen Peroxide is safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Is micronucleus assay a useful marker in gingiva, tongue, and palate for evaluating cytogenetic damage induced by chemical, physical, and biological agents in vivo? A systematic review with meta-analysis

The present systematic review (SR) aims to evaluate manuscripts in order to help further elucidate the following question: is the micronucleus assay (MA) also a useful marker in gingiva, tongue, and palate for evaluating cytogenetic damage in vivo? A search was performed through the electronic databases PubMed/Medline, Scopus, and Web of Science, all studies published up to December 2023. The comparisons were defined as standardized mean difference (SMD), and 95% confidence intervals (CIs) were established. Full manuscripts from 34 studies were carefully selected and reviewed in this setting. Our results demonstrate that the MA may be a useful biomarker of gingival tissue damage in vivo, and this tissue could be a useful alternative to the buccal mucosa. The meta-analysis analyzing the different sites regardless of the deleterious factor studied, the buccal mucosa (SMD = 0.69, 95% CI, - 0.49 to 1.88, p = 0.25) and gingiva (SMD = 0.31, 95% CI, - 0.11 to 0.72, p = 0.15), showed similar results and different outcome for the tongue (SMD = 1.19, 95% CI, 0.47 to 1.91, p = 0.001). In summary, our conclusion suggests that the MA can be a useful marker for detecting DNA damage in gingiva in vivo and that this tissue could be effective site for smearing.

Potentially carcinogenic effects of hydrogen peroxide for tooth bleaching on the oral mucosa: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Little is known about the extent to which hydrogen peroxide as used for tooth bleaching could be carcinogenic to the oral mucosa.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate whether hydrogen peroxide as used for tooth bleaching has carcinogenic effects on the oral mucosa.

MATERIAL AND METHODS

PubMed, Web of Science, Scopus, and Embase electronic databases were searched. Studies evaluating different outcomes potentially related to the carcinogenic effects of hydrogen peroxide for tooth bleaching on the oral mucosa were included. Risk of bias was assessed by the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE), Risk Of Bias in Non-randomized Studies of Interventions (ROBINS-I), or Risk of Bias 2 (RoB 2) tools. The strength of the evidence was assessed by using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) protocol. The quantitative analysis was performed with means, standard deviations, and 95% confidence intervals (CIs). Heterogeneity was analyzed by using I-squared statistics.

RESULTS

Thirteen articles comprising 5 animal and 8 clinical studies met the inclusion criteria. Three of the 5 animal studies associated the bleaching agents with a carcinogen and demonstrated an enhancement of the carcinogenic effect, but probably with the bleaching agent acting only as a promoter. Five clinical studies concluded that the bleaching agents did not cause mutagenic stress on the oral mucosa by using the micronucleus test. The meta-analysis demonstrated that the frequency of micronuclei did not differ significantly between baseline and 30 days after bleaching (mean difference: 0.48; 95% CI, -1.49, 2.46; P=.63).

CONCLUSIONS

This systematic review indicated that hydrogen peroxide does not appear to have carcinogenic effects on the oral mucosa.

Cytotoxicity and genotoxicity of whitening toothpastes in buccal mucosal cells: a randomized controlled trial

OBJECTIVES

To assess genotoxic and cytotoxic effect of commercially available toothpastes with the different whitening ingredients.

MATERIALS AND METHODS

In vivo assessment of cytotoxicity and genotoxicity of whitening toothpastes with different ingredients using a buccal micronucleus cytome assay (BMCyt assay) comprised 199 participants randomly divided into ten groups based on used whitening or control/conventional toothpaste. The exfoliated buccal mucosal cells were collected, stained, and microscopically evaluated at baseline (T0), 30 days (T1), and 60 days (T2) after the beginning of treatment and 30 days after completing treatment (T3). Statistical evaluation was performed by repeated-measures analysis of variance (two-way ANOVA), Tukey's test, and multiple regression analysis.

RESULTS

The genotoxic parameters showed no biologically significant changes in any of the observed period for the tested toothpastes, while cytotoxic parameters (number of cells with karyorrhexis and condensed chromatin) showed statistically significant difference (P < 0.05) among evaluation periods for the three peroxide-containing toothpastes.

CONCLUSIONS

Peroxide-containing whitening toothpastes exhibit an increase in certain cytotoxic parameters only during the application period, which return to control values after the cessation of application.

CLINICAL SIGNIFICANCE

Whitening toothpastes show no genotoxic effect, while peroxide-containing whitening toothpastes may present significant increase of cytotoxicity (measured by the number of karyorrhexis and condensed chromatin) during the application period. However, these changes observed in clinical conditions cannot be considered significant.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04460755.

The influence of smoking on the effectiveness of at-home bleaching: A prospective clinical study

OBJECTIVES

To evaluate the effect of smoking on tooth whitening and color change after at-home bleaching.

MATERIALS AND METHODS

This prospective clinical study evaluated two groups of participants: NS-non-smokers (n = 24) and S-smokers (n = 16). All subjects were treated with at-home bleaching using 22% carbamide peroxide (CP) for 1 h/day for 14 days. Color coordinates (L*-luminosity, a*-red-green axis and b*-yellow-blue axis) were obtained before bleaching (D0-baseline), 1 day (D1), 15 days (D15), and 1 month (D30) after bleaching. The whiteness index (WID ) and CIEDE2000 color differences (ΔE00 ) were calculated for S and NS. Color changes between S and NS subjects for specific teeth (CI-Central Incisors, LI-Lateral Incisors, and C-Canines) were analyzed using the Mann-Whitney test (α = 0.05).

RESULTS

There was no significant difference in WID between S and NS subjects at baseline. NS participants showed higher WID than S at D1, D15, and D30 (p < 0.05). NS showed higher ΔWID for CI and C between D0 and the other evaluation times (D1, D15, and D30) compared to S. Smokers showed higher darkening of CI than NS in ΔWID D30-D1 (p < 0.05). Color changes showed similar overall behavior for ΔWID . For all evaluation times, ΔWID and ΔE00 values were below the corresponding acceptability thresholds.

CONCLUSION

At-home bleaching was effective on smokers and nonsmokers. Smoking negatively affected color stability after bleaching. ΔE00 and ΔWID were acceptable for both groups.

CLINICAL SIGNIFICANCE

Although smoking negatively affected color stability after bleaching, the observed changes were clinically acceptable.

Genotoxicity in the oral cells of older people from a Brazilian rural area: a population-based study

The purpose of this population-based, observational, and cross-sectional study was to evaluate alterations in the oral cells of a population of older people from a Brazilian rural area, using the micronucleus technique to investigate possible associated genotoxic factors. A questionnaire was applied and clinical examination and collection of oral mucosal cells were performed for all older people (≥ 60 years) from a town in southern Brazil. Demographic and socioeconomic variables, deleterious habits (drinking and tobacco use), presence of gastro-oesophageal reflux disease (GERD), and the use of proton pump inhibitors (PPIs) were considered the exposure variables, whereas metanuclear changes (MCs) and the prevalence of cell micronuclei (MN) were considered outcomes. Out of 489 older people, 447 were included in the study, among whom 50.8% were men with a mean age of 70.9 years and 83.9% had a monthly family income greater than US$ 500.00. GERD symptoms were present in 36.2% of the individuals, and 29.1% used PPIs daily, 53.3% consumed alcoholic beverages, and 46.7% used tobacco. The analysis of 1,000 oral mucosal cells per subject showed a MN frequency of 0-2 per individual, and MCs were detected with an average of 15 units per individual (median = 11 per individual). Poisson regression did not show statistical association between the exposure variables and the outcomes (presence of MN and MCs), except for the use of PPIs, which was a protective factor for the prevalence of MN [PR 0.6 (CI 0.3-0,9)]. Age, sex, family income, tobacco use and drinking, and GERD were not associated with the number of MN and MCs in oral mucosal cells of the investigated older people.

In-vitro evaluation of the effectiveness of polyphenols based strawberry extracts for dental bleaching

To formulate a dental bleaching agent with strawberry extract that has potent bleaching properties and antimicrobial efficacy. Enamel specimens (3 × 3 × 2 mm³) were prepared. Quaternary Ammonium Silane (CaC2 enriched) was homogenized with fresh strawberries: Group 1: supernatant strawberry (10 g) extract < Group 2: supernatant strawberry (10 g) extract + 15%HA (Hydroxyapatite) < Group 3: supernatant strawberry (10 g) extract + 15% (HA-2%k21) < Group 4: supernatant strawberry (20 g) extract only (20 g strawberries) < Group 5: supernatant strawberry (20 g) extract + 15% HA < Group 6: supernatant strawberry (20 g) extract + 15% (HA-2%K21) < Group 7: In-office Opalescence Boost 35%. Single-colony lactobacillus was examined using confocal microscopy identifying bacterial growth and inhibition in presence of bleaching agents using 300 µL aliquot of each bacterial culture. Images were analysed by illuminating with a 488 nm argon/helium laser beam. Colour difference (∆E00) was calculated using an Excel spreadsheet implementation of the CIEDE2000 colour difference formula and colour change measured between after staining and after bleaching. Scanning electron microscope was used to image specimens. Raman spectra were collected, and enamel slices were used for STEM/TEM analysis. HPLC was used for strawberry extract analysis. Nano-indentation was performed and X-ray photoelectron spectroscopy. Antioxidant activity was determined along with molecular simulation. hDPSCs were expanded for Alamar Blue Analysis and SEM. Mean colour change was significantly reduced in group 1 compared to other groups (p < 0.05). CLSM showed detrimental effects of different strawberry extracts on bioflms, especially with antimicrobial (p < 0.05). Groups 1, 2 and 3 showed flatter/irregular surfaces with condensation of anti-microbial in group 3. In strawberry specimens, bands predominate at 960 cm^-1. HPLC determined the strawberry extracts content. Molecular simulation verified interaction between calcium and polyphenol components. XPS peak-fitted high-resolution corresponding results of Ca2p_3/2 and Ca2p_1/2 for all k21 groups. Combination of 10 g strawberry extract supernatant and 15% (hydroxyapatite 2%k21) improved the whiteness and provided additional antimicrobial potential. The novel strawberry extract and antimicrobial based dental formulation had immediate bleaching effect without promoting significant changes in enamel morphology.

Influence of smoking on oral cells genotoxicity after at-home bleaching using 22% carbamide peroxide: a cohort study

OBJECTIVE

This study evaluated the influence of smoking on the oral cells genotoxicity before and after at-home bleaching using 22% carbamide peroxide (CP).

MATERIALS AND METHODS

This is a prospective observational analytics cohort study which evaluated nonsmokers (NS; n = 24) and smokers (S; n = 16) patients. At-home bleaching was performed using 22% CP gel in individual trays for 1 h per day for 14 days in both groups. Scrapped cells from marginal gums were collected before the bleaching treatment (D0-baseline) and 1 day (D1), 15 days (D15), and 1 month (D30) after its finishing. Cells were stained with Giemsa 10%, and the micronucleus (MN) and metanuclear alterations (MA) were counted by a trained operator in 1000 cells per patient. The collections and data analysis occurred blindly. Data was analyzed by Kruskal-Wallis, Dunn, and Mann-Whitney test (α = 0.05).

RESULTS

MN frequency was not influenced by smoking or bleaching. An increase of MA was observed between D0 and D30 for both groups (p < 0.001); however, no statistical difference was found between NS and S (p > 0.05) in the evaluation times.

CONCLUSION

Smoking associated with 22% carbamide peroxide gel for at-home bleaching does not show genotoxic potential analyzed by the MN counts. However, a significant increase of MA was found for smokers and nonsmokers.

CLINICAL RELEVANCE

Despite of the increase in MA, smoking associated with 22% CP peroxide at-home bleaching showed no important genotoxic potential (MN) for oral cells. Therefore, at-home bleaching treatment is safe for nonsmokers and smokers even with a high carbamide peroxide concentration of 22%.

Combination of strontium chloride and photobiomodulation in the control of tooth sensitivity post-bleaching: A split-mouth randomized clinical trial

Objective

This split-mouth randomized controlled clinical trial assessed the effect of 10% strontium chloride in combination with photobiomodulation (PBM) for the control of tooth sensitivity (TS) post-bleaching.

Methods

The upper/lower, right and left quadrants of fifty volunteers were randomized and allocated to four groups (n = 25): PLACEBO—placebo gel + simulation of PBM; Placebo + PBM; STRONTIUM—10% strontium chloride + simulation of PBM; and PBM + STRONTIUM—10% strontium chloride + PBM. All groups received tooth bleaching treatment with 35% hydrogen peroxide. For the PBM treatment, the laser tip was positioned in the apical and cervical regions of the teeth bleached in the respective hemi-arch. The laser system was operated in continuous mode, using 1.7 J of energy. A dose of 60 J/cm² was applied to each point for 16 seconds under 808 nm near-infrared light (100mW of power), with a point area of 0.028 cm². TS was assessed during a 21-day follow-up, using the modified visual analogue scale.

Results

In the intragroup assessment, the Friedman test indicated that PBM + STRONTIUM promoted the greatest reduction in TS after the second week of treatment (p ≤ 0.05). The Wilcoxon-Mann-Whitney test indicated that the groups Placebo + PBM, STRONTIUM, and STRONTIUM + PBM did not differ statistically (p ≥ 0.05) in the first and third weeks of treatment The group PLACEBO exhibited the greatest TS in the first three days after each bleaching session.

Conclusion

The combination of 10% strontium chloride with PBM was effective in reducing post-bleaching TS; however, the combination of 10% strontium chloride with PBM was effective in reducing post-bleaching TS; however, it did not differ from the individual use of Placebo + PBM or STRONTIUM groups assessed after 21 days of follow-up.

Effect of different bleaching techniques on DNA damage biomarkers in serum, saliva, and GCF

Bleaching agents containing a high concentration of H₂O₂ in the dental market lead to formation of reactive oxygen species, which have genotoxic effects. However, ozone bleaching, one of the most effective oxidants known, stimulates blood circulation and immune response and thus it has strong antimicrobial activity against viruses, bacteria, fungi, and protozoa. For these reasons, one of our hypothesis was ozone bleaching would reduce local and systemic DNA damage in the body. Hence, we aimed to determine the oxidative DNA damage biomarker levels in serum, saliva, and gingival crevicular fluid (GCF) by measuring 8-hydroxy-2'-deoxyguanosine (8-OHdG) after different bleaching methods.Forty-eight volunteers who requested dental bleaching were divided into three treatment groups (n = 16). Group 1: ozone bleaching with the ozone-releasing machine; Group 2: chemical bleaching with 40% hydrogen peroxide (H₂O₂) gel; Group 3: 40% H₂O₂ gel activated with the diode laser. Initial and post-operative (immediately after bleaching and two weeks later) color measurements were performed with a spectrophotometer. The color changes were calculated with the CIEDE2000 (ΔE ₀₀) formula. 8-OHdG levels in serum, saliva, and GCF samples were determined with ELISA. All three treatments resulted in efficient and statistically similar bleaching. The 8-OHdG levels in the serum and saliva were not affected by all bleaching methods (p > 0.05), but a temporary increase was observed in the GCF for chemical and laser-assisted groups except the ozone group (p > 0.05). According to the findings, chemical and laser-assisted bleaching can affect DNA damage locally but not systemically. Bleaching with ozone may eliminate this local DNA damage.

In vivo evaluation of the genotoxicity and oxidative damage in individuals exposed to 10% hydrogen peroxide whitening strips

OBJECTIVE

This study assessed the impact of 10% hydrogen peroxide whitening strip exposure on the genotoxicity and oxidative damage by means of the buccal micronucleus cytome assay by counting nuclear abnormalities (NAs) in buccal mucosa and attached gingiva cells and by analyzing in whole saliva the molecule 8-hydroxy-2'-deoxyguanosine (8-OHdG).

MATERIALS AND METHODS

The study was conducted on 113 subjects divided into two groups: group 1 or control (n = 53), non-whitening strip exposed, and group 2 (n = 60), whitening strip exposed (Crest® 3D Whitestrips® premium plus, 10% hydrogen peroxide). Oral epithelial cells and whole saliva samples were taken at the beginning and 30 days later for group 1 and immediately before bleaching and 15 and 30 days after the end of the bleaching for group 2.

RESULTS

An increased frequency of NAs (p < 0.05) and higher levels of 8-OHdG (p < 0.05) were observed after bleaching exposure. Also, a positive correlation exists between oxidative stress produced by hydrogen peroxide and micronuclei was found.

CONCLUSION

Individuals exposed to 10% hydrogen peroxide whitening strips exhibit NAs increased in oral epithelial cells and 8-OHdG in saliva, which is directed related to nuclear and oxidative DNA damage, respectively.

CLINICAL SIGNIFICANCE

Hydrogen peroxide is the active agent of tooth whitening and this compound induced DNA damage. Individuals exposed to whitening strips with 10% hydrogen peroxide exhibit increased genotoxic and oxidative damage. Therefore, self-application of bleaching agents should be handled carefully since it could be a risk to human health.

Evaluation of in-office tooth whitening treatment with violet LED: protocol for a randomised controlled clinical trial

INTRODUCTION

In-office tooth whitening treatment using violet light emited diode (LED) (405 nm) is a novel bleaching method that causes less sensitivity while offering the same effectiveness as the gold standard (35% hydrogen peroxide, H₂O₂). This study describes a protocol for the first randomised controlled clinical trial to compare the effects of the two methods.

METHODS AND ANALYSIS

Eighty patients will be divided into four groups: G1 violet LED; G2 violet LED +35% carbamide peroxide; G3 35% H₂O₂ and G4 violet LED +gingivoplasty. Colour will be measured at baseline, immediately after the first session and at the 15 and 180 days follow-up using the Vita Classical and the digital Easyshade V spectrophotometer (Vita, Zahnfabrik, Germany). Sensitivity after whitening will be measured using the Visual Analogue Scale at baseline and at each session in all groups and in all follow-ups. The tissue removed during gingivoplasty (G4) will be submitted to immunohistochemical analysis for the determination of inflammatory changes caused by violet LED. The Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) will be evaluated before, as well as at established time point controls. The results will be expressed as mean and SD values. After determining the normality of the data, a one-way repeated-measures analysis of variance will be used for the comparison of data with normal distribution and the Kruskal-Wallis test will be used for data with non-normal distribution. A p<0.05 will be considered indicative of statistical significance. After determining the normality of the data, the Kruskal-Wallis test will be used for non-parametric data. Multivariate analysis of variance (MANOVA) and the Wilcoxon test will be used for comparing data from the PIDAQ.

ETHICS AND DISSEMINATION

This protocol has been approved by the Human Research Ethics Committee of UniversidadeNove de Julho (certificate: 2.034.518). The findings will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT03192852; Pre-results.

Effect of topical application of dipyrone on dental sensitivity reduction after in-office dental bleaching: A randomized, triple-blind multicenter clinical trial

BACKGROUND

Tooth sensitivity commonly occurs during and immediately after dental bleaching. The authors conducted a trial to compare tooth sensitivity after in-office bleaching after the use of either a topical dipyrone or placebo gel.

METHODS

A split-mouth, triple-blind, randomized, multicenter clinical trial was conducted among 120 healthy adults having teeth that were shade A2 or darker. The facial tooth surfaces of the right or left sides of the maxillary arch of each patient were randomly assigned to receive either topical dipyrone or placebo gel before 2 in-office bleaching sessions (35% hydrogen peroxide) separated by 2 weeks. Visual analog and numerical rating scales were used to record tooth sensitivity during and up to 48 hours after bleaching. Tooth color change from baseline to 1 month after bleaching was measured with shade guide and spectrophotometer measures. The primary outcome variable was absolute risk of tooth sensitivity. An intention-to-treat analysis was used to analyze data from all patients who were randomly assigned to receive the dipyrone and placebo gels.

RESULTS

No statically significant difference was found in the absolute risk of tooth sensitivity between the dipyrone and placebo gels (83% and 90%, respectively, P = .09; relative risk, 0.92; 95% confidence interval, 0.8 to 1.0). A whitening effect was observed in both groups with no statistically significant difference (P > .05) between them. No adverse effects were observed.

CONCLUSION

Topical use of dipyrone gel before tooth bleaching, at the levels used in this study, did not reduce the risk or intensity of bleaching-induced tooth sensitivity.

PRACTICAL IMPLICATIONS

Topical application of dipyrone gel does not reduce bleaching-induced tooth sensitivity.

Evaluation of several clinical parameters after bleaching with hydrogen peroxide at different concentrations: A randomized clinical trial

OBJECTIVE

This randomized double-blind clinical trial compared tooth sensitivity (TS), bleaching efficacy, and cytokine levels after applying in-office bleaching treatments containing 15% and 35% hydrogen peroxide (HP15% and HP35%, respectively).

METHODS

Twenty-five volunteers were randomly assigned to receive HP15% or HP35% treatment. The bleaching agent was applied in three 15-min applications per session. Two bleaching sessions were separated by a 1-week interval. The participants scored TS using a visual analog scale and numerical rating scale. Bleaching efficacy was determined by subjective and objective methods. Gingival crevicular fluid was collected from three jaws sites per patient for the analysis of fluid volume. Flow cytometry was used to analyze gingival crevicular fluid levels of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor, and interferon-gamma. All measurements were obtained before and after bleaching. All data were statistically analyzed (α=0.05).

RESULTS

The absolute risk and intensity of TS was higher for HP35% than for HP15% (p>0.002). One month post-bleaching, HP35% produced more bleaching than HP15% (p=0.02). However patient perception (p=0.06) and patient satisfaction (p=0.53) with regard to bleaching were not significantly different. No significant differences existed in the gingival fluid volume (p>0.38) or in any cytokine level (p>0.05) for either HP concentration.

CONCLUSION

Treatment: with HP35% is more effective than HP15%, but generates a greater risk and intensity of TS. No inflammatory changes occurred despite the difference in the HP concentrations.

CLINICAL SIGNIFICANCE

Hydrogen peroxide at a lower concentration (e.g., 15%) should be considered a good treatment alternative for in-office bleaching because the higher concentration for in-office bleaching generates a greater risk and intensity of TS for patients.

Randomized clinical trials of dental bleaching - Compliance with the CONSORT Statement: a systematic review

We reviewed the literature to evaluate: a) The compliance of randomized clinical trials (RCTs) on bleaching with the CONSORT; and b) the risk of bias of these studies using the Cochrane Collaboration risk of bias tool (CCRT). We searched the Cochrane Library, PubMed and other electronic databases, to find RCTs focused on bleaching (or whitening). The articles were evaluated in compliance with CONSORT in a scale: 0 = no description, 1 = poor description and 2 = adequate description. Descriptive analyses of the number of studies by journal, follow-up period, country and quality assessments were performed with CCRT for assessing risk of bias in RCTs. 185 RCTs were included for assessment. More than 30% of the studies received score 0 or 1. Protocol, flow chart, allocation concealment and sample size were more critical items, as 80% of the studies scored 0. The overall CONSORT score for the included studies was 16.7 ± 5.4 points, which represents 52.2% of the maximum CONSORT score. A significant difference among journal, country and period of time was observed (p < 0.02). Only 7.6% of the studies were judged at "low" risk; 62.1% were classified as "unclear"; and 30.3% as "high" risk of bias. The adherence of RCTs evaluating bleaching materials and techniques to the CONSORT is still low with unclear/high risk of bias.