Genotoxicity of non-alcoholic mouth rinses: A micronucleus and nuclear abnormalities study with fluorescent microscopy

In vitro analysis of various mouthwashes: cytotoxic, apoptotic, genotoxic and antibacterial effects

OBJECTIVE

This study aims to investigate the cytotoxic, apoptotic, and genotoxic effects of eleven mouthwashes, which are hypothesized to pose potential toxic risks to oral mucosal tissues, through in-vitro experiments using human gingival fibroblast(hGF) cell cultures and to compare the antibacterial efficacy of these mouthwashes.

MATERIALS AND METHODS

Healthy hGF cell lines were derived from individuals under ethical standards. The cytotoxic effects of the mouthwashes (Colgate 2in1,Colgate Optic White, Colgate Plax, Curasept, Elmex, Kloroben, Listerine Cool Mint, Listerine Zero, Meridol, Oral-B Pro Expert, Sensodyne Pronamel) were assessed in real-time using the xCELLigence system, which monitored cellular activity at 5-minute intervals over 72 h. Apoptotic effects of the IC50 concentrations of the mouthwashes on hGF cells were evaluated using Annexin V and Caspase-3 assays. Genotoxic effects at IC50 concentrations were analyzed through the Alexa Fluor® 488 Mouse anti-H2AX assay. The antibacterial effect of mouthwashes on Streptococcus mutans and Lactobacillus rhamnosus was evaluated by modified microdilution method.

RESULTS

According to the analysis of the IC50 values, Meridol was found to be the most cytotoxic mouthwash, while Listerine Zero was the least cytotoxic. The mouthwashes can be ranked in order of their cytotoxicity as follows: Meridol(0.011) > Elmex(0.029) > Colgate 2in1(0.187) > Colgate Plax(0.478) > Colgate Optic White (0.534) > Sensodyne Pronamel(0.577) > Oral-B Pro Expert(0.638) > Kloroben(0.766) > Curasept(1.872) > Listerine Cool Mint(2.334) > Listerine Zero(7.267)(p < 0.05). The Annexin V assay showed no major apoptotic impacts on human gingival fibroblast cell line at the IC50 values of the mouthwashes, except for Colgate Plax, Kloroben, and Oral B Pro Expert. The IC50 values of the evaluated mouthwashes did not show a significant apoptotic effect on the hGF cell line as evaluated by Caspase-3 assay and no significant genotoxic effect was observed as evaluated by H2AX assay(p > 0.05). Colgate Plax showed the most effective antibacterial effect on Streptococcus mutans and Lactobacillus rhamnosus(p < 0.05).

CONCLUSION

Mouthwash formulations showed varying cytotoxic effects on hGF and different antibacterial effectiveness. Essential oil-containing mouthwashes may be preferable to those with chlorhexidine or cetylpyridinium chloride, as they demonstrate less cytotoxicity, are more biocompatible, and have antibacterial efficacy.

CLINICAL RELEVANCE

The low cytotoxicity and potent antibacterial properties of essential oils render them a more safer choice for inclusion in mouthwash compositions.

The effect of oil pulling in comparison with chlorhexidine and other mouthwash interventions in promoting oral health: A systematic review and meta-analysis

OBJECTIVES

A meta-analytic review was performed to critically synthesize the evidence of oil pulling on improving the parameters of gingival health, plaque control and bacteria counts against chlorhexidine and other mouthwash or oral hygiene practices.

METHODS

Databases including Medline, Embase and bibliographies were searched from inception to 1 April 2023. Randomized controlled trials (RCTs) with 7 days or longer duration of oil pulling with edible oils in comparison to chlorhexidine or other mouthwashes or oral hygiene practice concerning the parameters of plaque index scores (PI), gingival index scores (GI), modified gingival index scores (MGI) and bacteria counts were included. Cochrane's Risk of Bias (ROB) tool and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework were employed to determine the quality of evidence. Two authors independently conducted study selection and data extraction. Meta-analyses of the effect of oil pulling on the parameters were conducted using an inverse-variance random-effects model.

RESULTS

Twenty-five trials involving 1184 participants were included. Twenty-one trials comparing oil pulling (n = 535) to chlorhexidine (n = 286) and non-chlorhexidine intervention (n = 205) were pooled for meta-analysis. More than half of the trials (n = 17) involved participants with no reported oral health issues. The duration of intervention ranged from 7 to 45 days, with half of the trials using sesame oil. When compared to non-chlorhexidine mouthwash interventions, oil pulling clinically and significantly improved MGI scores (Standardized mean difference, SMD = -1.14; 95% confidence interval [CI]: -1.31, -0.97). Chlorhexidine was more effective in reducing the PI scores compared to oil pulling, with an SMD of 0.33 (95% CI: 0.17, 0.49). The overall quality of the body of evidence was very low.

CONCLUSIONS

There was a probable benefit of oil pulling in improving gingival health. Chlorhexidine remained superior in reducing the amount of plaque, compared to oil pulling. However, there was very low certainty in the evidence albeit the clinically beneficial effect of oil pulling intervention.

Antimicrobial photodynamic therapy mediated by methylene blue in surfactant vehicle as adjuvant to periodontal treatment. Randomized, controlled, double-blind clinical trial

BACKGROUND

Antimicrobial photodymanic therapy mediated by methylene blue has been investigated as an adjunctive to periodontal treatment but the dimerization of photosensitizer molecules reduces the phototoxic effects. Sodium dodecyl sulfate is a surfactant that may control this aggregation. The aim of this study was evaluated the photodynamic effect of methylene blue in sodium dodecyl sulfate in periodontitis.

METHODS

36 participants with periodontitis were selected and allocated randomly in two group for intervention and other two for control - all of them were treated with scaling and root planing before aPDT. Three periodontal evaluations were done: at the selection time, at the day of intervention and thirty-day after this. Pre-irradiation time was 1 min and 2 min for irradiation. Laser (Therapy XT, DMC, São Carlos, Brazil) with wavelength of 660 nm and 100 mW of power was used. Two photosensitizer solutions with 100 µM methylene blue was used, one of them was in water and other in 0,25% of sodium dodecyl sulfate. Two sites of each participant were selected for the experimental procedures. Microbiological evaluations were performed to quantify microorganisms before and immediately after intervention. Quantitative microbiological evaluation was the primary outcome; morphological aspects of bacterial colony, and clinical probing depth was the secondary one.

RESULTS

There was no significant difference between the groups in both bacterial reduction and the clinical parameter evaluated.

CONCLUSION

The effect of methylene blue in surfactant did not cause enough phototoxic effects that could promote reduction of periodontal pocket depth.

Efficacy of Chitosan and Chlorhexidine Mouthwash on Dental Plaque and Gingival Inflammation: A Systematic Review

Mouthwash is the effective chemical plaque control mechanism being practiced globally. Teeth and tongue discoloration, a temporary change in taste perception, an increase in calculus deposits, a burning sensation, and genotoxicity of buccal epithelial cells are all possible side effects. This review evaluates the efficacy of chitosan mouthwash in comparison to chlorhexidine mouthwash in combating plaque accumulation and gingival inflammation. Electronic databases such as Medline, Cochrane, LILACS, TRIP, Google scholar, and clinical trial registries (CTRI) for ongoing trials were searched with appropriate medical subheadings (MeSH) and search terms. Randomized clinical trials comparing the efficacy of chitosan mouthwash and chlorhexidine mouthwash on dental plaque accumulation and gingivitis were included. The outcome variables of interest were plaque index, gingival index, gingival bleeding index, and colony-forming unit (CFU/ml). All data from the included studies were extracted in a customized extraction sheet. The risk of bias across the studies was assessed using the Cochrane tool for intervention (ROB-2), which consisted of six domains. Of the included three studies, we found one study with an overall low risk of bias and two studies with an overall high risk of bias across the domains. Though there was a significant reduction in plaque accumulation, gingival inflammation, and colony-forming units on the use of chitosan mouthwash and chlorhexidine mouthwash separately, all three included studies reported that a combination of both be more effective.

Effect of Three Chlorhexidine-Based Mouthwashes on Human Gingival Fibroblasts: An In Vitro Study

Mouthwashes containing chlorhexidine (CHX) are deemed to be associated with dose-dependent side effects, including burning sensation and taste alteration. To overcome these drawbacks, mouthwashes with CHX at lower concentrations with or without adjunctive agents are proposed. The aim of this in vitro study was to investigate the effects of three CHX-based mouthwashes on human gingival fibroblasts (HGFs). After 3 days of cell culture, groups were randomly treated for 30 s, 60 s or 120 s with (a) CHX 0.05% in combination with cetylpyridnium chloride (CPC) 0.05%; (b) CHX 0.1%; (c) CHX 0.2%; or (d) NaCl as control. Cell viability, cytotoxicity and apoptosis were evaluated at 2 h, 3 days and 6 days after the exposure to the different solutions. Similar cell viability values were found among the test groups at all time points. At day 0, higher cytotoxicity was measured in the group treated with CHX 0.02%, in particular after long application time (120 s), while no significant difference was found between CHX + CPC and the control group. All the investigated mouthwashes were well tolerated by HGF cells for the tested application times. The highest cytotoxic effect was observed for CHX 0.2%; therefore, clinicians should consider limiting its usage to carefully selected clinical situations.

Investigations concerning the impact of consumption of hot beverages on acute cytotoxic and genotoxic effects in oral mucosa cells

Consumption of very hot beverages and foods increases the incidence of oral and esophageal cancer but the mechanisms are not known and the critical temperature is not well defined. We realized a study with exfoliated cells from the oral cavity of individuals (n = 73) that live in an area in Iran which has the highest incidence of EC worldwide. Consumption of beverages at very high temperatures is a characteristic feature of this population. We analyzed biomarkers which are (i) indicative for genetic instability (micronuclei that are formed as a consequence of chromosomal damage, nuclear buds which are a consequence of gene amplifications and binucleated cells which reflect mitotic disturbances), (ii) markers that reflect cytotoxic effects (condensed chromatin, karyorrhectic, karyolitic and pyknotic cells), (iii) furthermore, we determined the number of basal cells which is indicative for the regenerative capacity of the buccal mucosa. The impact of the drinking temperature on the frequencies of these parameters was monitored with thermometers. We found no evidence for induction of genetic damage but an increase of the cytotoxic effects with the temperature was evident. This effect was paralleled by an increase of the cell division rate of the mucosa which was observed when the temperature exceeded 60 °C. Our findings indicate that cancer in the upper digestive tract in drinkers of very hot beverages is not caused by damage of the genetic material but by an increase of the cell division rate as a consequence of cytotoxic effects which take place at temperatures over 60 °C. It is known from earlier experiments with rodents that increased cell divisions lead to tumor promotion in the esophagus. Our findings provide a mechanistic explanation and indicate that increased cancer risks can be expected when the drinking temperature of beverages exceeds 60 °C.

Comparative study of hyperpure chlorine dioxide with two other irrigants regarding the viability of periodontal ligament stem cells

Objectives

Periodontal ligament stem cells (PDLSCs) have an underlined significance as their high proliferative capacity and multipotent differentiation provide an important therapeutic potential. The integrity of these cells is frequently disturbed by the routinely used irrigative compounds applied as periodontal or endodontic disinfectants (e.g., hydrogen peroxide (H₂O₂) and chlorhexidine (CHX)). Our objectives were (i) to monitor the cytotoxic effect of a novel dental irrigative compound, chlorine dioxide (ClO₂), compared to two traditional agents (H₂O₂, CHX) on PDLSCs and (ii) to test whether the aging factor of PDLSC cultures determines cellular responsiveness to the chemicals tested.

Methods

Impedimetry (concentration-response study), WST-1 assays (WST = water soluble tetrazolium salt), and morphology analysis were performed to measure changes in cell viability induced by the 3 disinfectants; immunocytochemistry of stem cell markers (STRO-1, CD90, and CD105) measured the induced mesenchymal characteristics.

Results

Cell viability experiments demonstrated that the application of ClO₂ does not lead to a significant decrease in viability of PLDSCs in concentrations used to kill microbes. On the contrary, traditional irrigants, H₂O₂, and CHX are highly toxic on PDLSCs. Aging of PLDSC cultures (passages 3 vs. 7) has characteristic effects on their responsiveness to these agents as the increased expression of mesenchymal stem cell markers turns to decreased.

Conclusions and clinical relevance

While the active ingredients of mouthwash (H₂O₂, CHX) applied in endodontic or periodontitis management have a serious toxic effect on PDLSCs, the novel hyperpure ClO₂ is less toxic providing an environment favoring dental structure regenerations during disinfectant interventions.

Electronic supplementary material

The online version of this article (10.1007/s00784-020-03618-5) contains supplementary material, which is available to authorized users.

Stannous Fluoride Effects on Enamel: A Systematic Review

In recent years there has been a lot of talk about toothpastes with a particular chemical compound: stannous fluoride (SnF2). Its presence is currently still highly controversial, as the latter could have negative health effects. The different companies that produce toothpastes express its dosage in ppm. The purpose of this systematic literature review is to analyze all randomized clinical trials in the literature over the last 10 years and to draw clear results on the function of stannous fluoride, for this purpose the authors performed a Mann-Whitney U Test.

MATERIALS

The first analysis of the literature produced a number greater than 800 results, subsequently applying the inclusion and exclusion criteria, and following a manual analysis of the results, 26 manuscripts have been obtained.

RESULTS

From the results analyzed in this review, it could be shown that stannous fluoride does not present important contraindications, if not those commonly reported for fluorine. A meta-analysis on enamel loss has been conducted, it shows that SnF2 products provide better results with a p < 0.05 value.

CONCLUSION

This compound could have significant effects in favor of erosion and recalcification of the enamel, on the biofilm formation, gingival inflammation, and in addition, it could be an important aid in the removal of tooth stains and halitosis.