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

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.

Over-the-counter products in tooth bleaching: A scoping review

OBJECTIVE

To map and summarize the current scientific evidence concerning the active ingredients, effectiveness, and adverse effects of over-the-counter (OTC) bleaching products.

DATA AND SOURCE

This study was conducted according to the PRISMA-ScR guidelines for scoping reviews and registered on the Open Science Framework platform.

STUDY SELECTION

Database searches were conducted in PubMed/MEDLINE, Embase, and Scopus up to January 2024. All in vitro, in situ, and clinical studies evaluating the effectiveness and adverse effects of OTC bleaching products were included. A descriptive analysis of the included studies was performed.

RESULTS

A total of 88 studies were included. Most of them were in vitro studies (n = 49), followed by randomized clinical trials (n = 28). The main OTC bleaching products identified were whitening or stain-removing toothpastes (n = 42), followed by whitening strips (n = 39). Most clinical studies indicate that whitening strips are effective in improving tooth color and providing whitening benefits. In contrast, the bleaching effectiveness of toothpastes, mouth rinses and whitening trays was mainly supported by in vitro studies. The main adverse effects associated with OTC bleaching agents were tooth sensitivity and gingival irritation.

CONCLUSION

A wide variety of OTC bleaching products is available for consumer self-administered use. Clinical studies have mainly confirmed the bleaching effectiveness of whitening strips, while the validation for toothpastes, mouth rinses and whitening trays has mainly relied on in vitro studies. Nevertheless, the use of OTC bleaching products may result in adverse effects, including tooth sensitivity, gingival irritation, and enamel surface changes.

CLINICAL SIGNIFICANCE

Some over-the-counter bleaching products may have whitening properties supported by clinical studies, particularly those containing hydrogen or carbamide peroxide. Nonetheless, clinicians must be aware of the potential risks associated with excessive self-administration of these products, which may result in adverse effects.

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.

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%.

The Effect of Selected Dental Materials Used in Conservative Dentistry, Endodontics, Surgery, and Orthodontics as Well as during the Periodontal Treatment on the Redox Balance in the Oral Cavity

Oxidative stress (OS) is a redox homeostasis disorder that results in oxidation of cell components and thus disturbs cell metabolism. OS is induced by numerous internal as well as external factors. According to recent studies, dental treatment may also be one of them. The aim of our work was to assess the effect of dental treatment on the redox balance of the oral cavity. We reviewed literature available in PubMed, Medline, and Scopus databases, including the results from 2010 to 2020. Publications were searched according to the keywords: oxidative stress and dental monomers; oxidative stress and amalgam; oxidative stress and periodontitis, oxidative stress and braces, oxidative stress and titanium; oxidative stress and dental implants, oxidative stress and endodontics treatment, oxidative stress and dental treatment; and oxidative stress and dental composite. It was found that dental treatment with the use of composites, amalgams, glass-ionomers, materials for root canal filling/rinsing, orthodontic braces (made of various metal alloys), titanium implants, or whitening agents can disturb oral redox homeostasis by affecting the antioxidant barrier and increasing oxidative damage to salivary proteins, lipids, and DNA. Abnormal saliva secretion/composition was also observed in dental patients in the course of OS. It is suggested that the addition of antioxidants to dental materials or antioxidant therapy applied during dental treatment could protect the patient against harmful effects of OS in the oral cavity.

The influence of violet LED light on tooth bleaching protocols: In vitro study of bleaching effectiveness

BACKGROUND

Employing violet LED on tooth bleaching is a recent but promising technique. This study aimed to assess the bleaching effectiveness of violet light-emitting diodes (LEDs) associated or not with bleaching gels containing hydrogen peroxide (HP) or carbamide peroxide (CP).

METHODS

seventy bovine incisors were randomly assigned into 7 groups (n = 10) according to the technique and whitening product used. Group C: Artificial saliva (placebo); Group HP L-: three sessions of HP at 35 % without light activation; Group CP L-: three weeks of CP at 16 % for 4 h/day; Group HP CP L-: three sessions of HP at 35 % without light activation + 2 weeks of CP at 16 %, for 4 h/day; Group LED: four sessions with violet LED; Group HP L+: three sessions with HP at 35 % + violet LED; Group CP L+: three weeks with CP at 16 % for 4 h/day + violet LED. Color changes (ΔE and ΔL) were measured with a portable digital spectrophotometer.

RESULTS

The results were similar between the groups of bleaching protocols, demonstrating that the use of the violet LED did not influence bleaching effectiveness when using HP 35 % or CP 16 % after 3 sessions. In addition, the use of the violet LED alone obtained ΔE values ​​similar to the protocols with the use of peroxides, however less variation of ΔL was observed for this group.

CONCLUSIONS

The use of violet LEDs associated or not with bleaching gels was effective for tooth whitening. In addition, it was also concluded that the physical lightening technique with violet LED used alone produced less variation in dental brightness.