Toothpaste detergents: a potential source of oral soft tissue damage?

Comparative evaluation of six commercial adult toothpaste formulations reveals cytotoxicity and altered functions in a human oral melanocyte model: an in vitro study

This study aims to compare six commercial adult toothpaste (labeled as A, B, C, D, E, and F) for cytotoxicity and melanocyte function alterations in vitro using primary human epidermal melanocytes from a Caucasian donor (HEMn-LP cells) as a model of oral melanocytes. Cells were incubated with toothpaste extracts (50% w/v) in culture media at dilutions (1:25, 1:50, 1:100, 1:200, 1:500, 1:800, and 1:1000) for 24 h. MTS and LDH assays were used to assess cytotoxicity. The effects of noncytotoxic toothpaste concentrations on melanocyte functional endpoints were then examined using spectrophotometric methods. All toothpaste showed concentration-dependent cytotoxicity that was heterogeneous across toothpaste containing SLS detergent. IC50 values of cytotoxicity followed the order: A = E > C > B > D > F. To compare toothpaste, they were tested at 1:800 and 1:1000 dilutions that were noncytotoxic after 24 h. None of the toothpaste affected cellular melanin production. However, toothpaste A, C, and D suppressed tyrosinase activity at both dilutions, while toothpaste B suppressed tyrosinase activity only at 1:800 dilution. Toothpaste A, C, E, and F elevated ROS production at 1:800 dilution, with no change at 1:1000 dilution. Toothpaste has a heterogeneous effect on melanocytes. Toothpaste B, E, and F at 1:1000 dilution were the safest as they did not alter melanocyte functions at this dilution, although toothpaste F is the least cytotoxic of these. Future studies are necessary to expand these results in a physiological environment of oral tissue. The findings of this study provide novel insight into the biocompatibility studies of toothpaste on oral melanocytes. They can aid dental practitioners and consumers in selecting noncytotoxic toothpaste that do not contribute to ROS generation by melanocytes in the oral cavity or lead to cytotoxicity and impaired cellular function.

Effect of Commercial Children's Mouthrinses and Toothpastes on the Viability of Neonatal Human Melanocytes: An In Vitro Study

In this study, we examined the cytotoxic effects of six commercial children's mouthrinses (designated as #1, #2, #3, #4, #5, and #6) and four commercial children's toothpastes (designated as #1, #2, #3, and #4) on primary human neonatal melanocytes that were used as a representative model for oral melanocytes. Mouthrinses diluted directly with culture medium (1:2, 1:5, 1:10, 1:100, and 1:1000) were added to monolayers of melanocytes for 2 min, followed by 24 h recovery, after which MTS cytotoxicity assay was conducted. The extracts of each toothpaste were prepared (50% w/v), diluted in culture medium (1:2, 1:5, 1:10, 1:50, 1:100, and 1:1000), and added to cell monolayers for 2 min (standard brushing time), followed by an analysis of cell viability after 24 h. Results showed that all mouthrinses except mouthrinse #4 showed significantly greater loss of cell viability, ascribed to cetylpyridinium chloride (CPC) that induced significant cytotoxicity to melanocytes (IC50 = 54.33 µM). In the case of toothpastes, the examination of cellular morphology showed that a 2 min exposure to all toothpaste extracts induced a concentration-dependent decline in cell viability, pronounced in toothpaste containing sodium lauryl sulfate (SLS) detergent. Further results suggested SLS to be the critical driver of cytotoxicity (IC50 = 317.73 µM). It is noteworthy that toothpaste #1 exhibited much lower levels of cytotoxicity compared to the other three toothpastes containing SLS. Taken together, these findings suggest that the melanocytotoxicity of children's mouthrinse (#4) and toothpaste (#1) is comparatively low. To the best of our knowledge, this is the first study to examine the impact of children's toothpastes and mouthrinses on neonatal primary human melanocytes. Future studies to investigate these findings in a realistic scenario replicating oral cavity conditions of the presence of microbiota, pellicle layer and saliva, and other cell types are warranted.

A Short Review of the Toxicity of Dentifrices-Zebrafish Model as a Useful Tool in Ecotoxicological Studies

This review aims to summarize the literature data regarding the effects of different toothpaste compounds in the zebrafish model. Danio rerio provides an insight into the mechanisms of the ecotoxicity of chemicals as well as an assessment of their fate in the environment to determine long-term environmental impact. The regular use of adequate toothpaste with safe active ingredients possessing anti-bacterial, anti-inflammatory, anti-oxidant, and regenerative properties is one of the most effective strategies for oral healthcare. In addition to water, a typical toothpaste consists of a variety of components, among which three are of predominant importance, i.e., abrasive substances, fluoride, and detergents. These ingredients provide healthy teeth, but their environmental impact on living organisms are often not well-known. Each of them can influence a higher level of organization: subcellular, cellular, tissue, organ, individual, and population. Therefore, it is very important that the properties of a chemical are detected before it is released into the environment to minimize damage. An important part of a chemical risk assessment is the estimation of the ecotoxicity of a compound. The zebrafish model has unique advantages in environmental ecotoxicity research and has been used to study vertebrate developmental biology. Among others, the advantages of this model include its external, visually accessible development, which allows for providing many experimental manipulations. The zebrafish has a significant genetic similarity with other vertebrates. Nevertheless, translating findings from zebrafish studies to human risk assessment requires careful consideration of these differences.

Cytotoxic effects of different detergent containing children's toothpastes on human gingival epithelial cells

Background

This study aimed to evaluate possible cytotoxic effects to gingival epithelial cells exposed to children toothpastes containing different detergent.

Methods

Tissues required for the isolation of human gingival epithelial cells were obtained by biopsy during the extraction of the impacted third molar tooth. Toothpaste solutions of different concentrations were prepared from five different children’s toothpastes with different detergent contents. Isolated gingival epithelial cells were stimulated with experimental groups consisting of toothpaste solutions (Colgate, Sensodyne, Splat, Nenedent, Perlodent) at different concentrations and a control group consisting of complete Dulbecco’s modified eagle medium. After the experiments, cell viability was evaluated using flow cytometry. 2 Way ANOVA was used to see the interaction effect of the main effects of toothpaste solution and concentration factors. Pairwise comparisons were made by Tukey post hoc tests. In the study, the significance level was taken as 0.05.

Results

As a result of the analysis, it was seen that the toothpaste solution and concentration factors and the interactions of these 2 factors were effective on the viable, early apoptotic, late apoptotic and necrotic cell rates. The statistically highest live cell ratios were detected in Splat’s toothpaste solutions (90.14% at 0.4% concentration) after the control group (90.82%) and the group with the lowest viability values was determined in Colgate group (75.74% at 0.4% concentration) (p < 0.05).

Conclusions

According to the results of the study, it was observed that toothpastes containing SLS affected the viability of cells more negatively than toothpastes with other detergent contents.

Effect of nonionic and amphoteric surfactants on salivary pellicles reconstituted in vitro

Surfactants are important components of oral care products. Sodium dodecyl sulfate (SDS) is the most common because of its foaming properties, taste and low cost. However, the use of ionic surfactants, especially SDS, is related to several oral mucosa conditions. Thus, there is a high interest in using non-ionic and amphoteric surfactants as they are less irritant. To better understand the performance of these surfactants in oral care products, we investigated their interaction with salivary pellicles i.e., the proteinaceous films that cover surfaces exposed to saliva. Specifically, we focused on pentaethylene glycol monododecyl ether (C12E5) and cocamidopropyl betaine (CAPB) as model nonionic and amphoteric surfactants respectively, and investigated their interaction with reconstituted salivary pellicles with various surface techniques: Quartz Crystal Microbalance with Dissipation, Ellipsometry, Force Spectroscopy and Neutron Reflectometry. Both C12E5 and CAPB were gentler on pellicles than SDS, removing a lower amount. However, their interaction with pellicles differed. Our work indicates that CAPB would mainly interact with the mucin components of pellicles, leading to collapse and dehydration. In contrast, exposure to C12E5 had a minimal effect on the pellicles, mainly resulting in the replacement/solubilisation of some of the components anchoring pellicles to their substrate.

Improving oral care for hospitalised patients: choosing appropriate products

BACKGROUND

Oral care is a fundamental part of nursing but it is often performed as a routine task, often based on historic practice, and lacks an evidence base. A variety of oral care products are used in practice.

AIM

To discover evidence of effective oral care products for use in hospitalised patients.

DESIGN

A systematic literature review was undertaken.

METHODS

A review of articles was conducted using CINAHL, PubMed, the Cochrane Database and Google Scholar between 2007 and 2019. All articles were compared and contrasted and some excluded due to the quality of the evidence.

DISCUSSION

The literature review identified a number of oral care problems and investigated a range of products.

RESULTS

The main finding was that there is a need for a definitive, evidence-based oral care guideline on the products suitable for different oral care conditions, including dysphagia, xerostomia, mucositis, and for patients wearing dentures.

Comparison of antiplaque effectiveness of herbal toothpaste: A randomized triple-blinded cross-over clinical trial

Background

Cleansing the teeth with a toothbrush and paste is an indubitable mechanical plaque control method practiced by almost everyone. Eliminating dental plaque is an essential, fundamental and mandatory step to prevent the occurrence of periodontal diseases that are rife globally. The aim of the present study is to compare the antiplaque effectiveness of a prepared herbal and commercially available dentifrice.

Materials and Methods

Thirty healthy individuals within the age group of 18-25 years were recruited to participate in the study. After achieving induced gingivitis and measuring plaque levels using Turesky modification of the Quigley Hein Plaque index in all the subjects, they were randomly divided into test arms A and B. Commercial dentifrice was distributed to one group, whereas the other group received prepared herbal dentifrice. Supervised brushing was carried out for 5 min, and plaque amounts after brushing were noted. After a washout period of 1 week, the same steps were repeated as per the cross-over study protocol. Unpaired t-test and paired t-tests were employed with P < 0.05.

Results

Both the toothpastes show the difference in plaque scores immediately after brushing when compared to baseline and was statistically significant (P = 0.001). The mean plaque scores of commercial dentifrice (1.93 ± 1.52) were less than that of the prepared herbal dentifrice (2.35 ± 1.39) after brushing.

Conclusion

The prepared herbal dentifrice had good antiplaque action. However, the plaque inhibitory action of self-prepared herbal toothpaste was marginally less when compared to commercial dentifrice.

In vivo evaluation of fluoride and sodium lauryl sulphate in toothpaste on buccal epithelial cells toxicity

OBJECTIVES

The present study addresses the effect of fluoride and sodium lauryl sulphate content of toothpaste on oral epithelial cells in vivo conditions.

SUBJECTS AND METHOD

Forty volunteers were assigned into two experimental groups, each of them applying the different brand of toothpaste. Every group has been using three different types of toothpaste (non-fluoride and non-SLS, fluoride and non-SLS, and the fluoride and SLS) of the same brand for 6 months, each for 2 months. The buccal epithelial cells were sampled at baseline and 30, 60, 90, 120, 150 and 180 days after the beginning of the research. Effect on DNA damage was analyzed by micronucleus assay Results: After 60 days of use, for both tested kinds of toothpaste with fluoride and without SLS, all studied parameters were not significantly different from the results obtained at the time when the participants used a non-fluoride toothpaste. While, after 60 days of use, for one kind of toothpaste with SLS and fluoride, was observed significantly higher incidence of pyknotic cells (2.20 ± 0.95, 0.00 ± 0.00 vs. 0.05 ± 0.22, respectively; p = .001), cells with karyorrhexis (2.35 ± 1.14, 0.85 ± 0.93 vs. 0.40 ± 0.68, respectively; p = .001), and nuclear buds (1.35 ± 0.68, 0.45 ± 0.51 vs. 0.45 ± 0.60, respectively; p = .001), compared to toothpastes of the same brand with fluoride and without SLS, and without fluoride and without SLS, for the same period.

CONCLUSIONS

Based on the results, can be concluded that there is no fluorine-dependent cytotoxic or genotoxic effect, while SLS dentifrice increases the number of nuclear morphological changes in buccal epithelial cells.

Dry brushing: Does it improve plaque removal? A secondary analysis

OBJECTIVE

This article is a secondary analysis comparing the effects on plaque removal of brushing with a dry toothbrush and brushing with a prewetted toothbrush.

METHODS

The participants had been included in two previous experiments involving single-brushing exercises. The 46 non-dental participants were systemically healthy and ≥18 years of age. In the first experiment, the control intervention was brushing with a prewetted toothbrush, while during the second experiment it was brushing with a dry toothbrush. Both experiments scored plaque before and after the brushing exercises and assessed participants' perception. The data of these two previous experiments were compared in this secondary analysis.

RESULTS

Plaque score reduction following brushing with a dry toothbrush was 58%, while with a prewetted toothbrush, it was 57%. The mean plaque index score reduction of 0.08 between a dry and a prewetted toothbrush was not significant (P = .096). Prewetting the participants' toothbrush had no influence on the perception of toothbrush filament stiffness (P = .410) nor on the perception of cleaning capability (P = .449). In both experiments, brushing without dentifrice was judged to be unpleasant.

CONCLUSION

On average, following a 2-minute brushing exercise, plaque scored were reduced by 57% or more. Dry brushing did not contribute significantly to toothbrush efficacy. The participants did not find that prewetting a toothbrush influenced the cleaning capability and filament stiffness.

A specific brushing sequence and plaque removal efficacy: a randomized split-mouth design

AIM

It has been propagated by the dental care professionals to start toothbrushing the lingual aspect of teeth first. In general, it is assumed that these surfaces of teeth are more difficult to clean. The evidence to support this recommendation is sparse.

METHOD

In this randomized controlled clinical trial using a split-mouth design, 46 students were included. Before the visit, the participants were requested to refrain from any oral hygiene procedure for 48 h. First, the plaque index (PI) score was assessed full mouth. Two randomly chosen contra-lateral quadrants were used to start brushing from the lingual aspect first. The opposing two quadrants were used to start brushing from the buccal aspect. After the brushing exercise was completed, full-mouth PI was scored again. Subanalyses were performed for the buccal, lingual and approximal surfaces.

RESULTS

At baseline, there was no statistically significant difference between the two sets of contra-lateral quadrants (P = 0.770). Starting at the lingual aspect of the lower jaw resulted in a 55% reduction of plaque scores in comparison with 58% when the brushing exercise was started buccally. [Correction added on 16 January 2017, after first online publication: In the preceding sentence, the percentage reduction of plaque scores when the brushing exercise was started buccally, was previously wrong and has been corrected to 58% throughout this article.] The difference in mean plaque scores between brushing orders was 0.04, which was not significant (P = 0.219). None of the subanalyses revealed any significant differences for the isolated surfaces.

CONCLUSION

Using a manual toothbrush reduced the plaque scores between 55 and 58% with no difference between brushing from either the lingual or buccal aspect first. Within the limitations of this study, a recommendation to start toothbrushing the lingual aspect is not supported by the outcome in this young student population.

The practical evaluation and management of patients with symptoms of a sore burning mouth

There are many etiologic factors to consider in a patient who presents with symptoms or sensations of a sore burning mouth. These range from local causes within the oral cavity to underlying systemic disease, including psychologic factors. This paper aims to describe the different clinical presentations and to outline a systematic approach to the evaluation and management of such patients. The clinician will be directed to the relevant diagnosis by following the traditional medical model of taking a focused history, performing a thorough clinical examination, considering the potential differential diagnoses, and requesting pertinent and appropriate investigations. The various differential diagnoses and broad treatment options will also be discussed and outlined. This paper will not, however, discuss burning mouth syndrome (oral dysesthesia), which is a diagnosis of exclusion, whereby the oral mucosa is clinically normal and there are no identifiable medical or dental causes to account for the patient's symptoms.

Dentifrices for children differentially affect cell viability in vitro

Objectives

Child dentifrices vary in their composition, with possible differential impacts on cells in the oral soft tissue. While cytotoxicity studies have been performed on adult dentifrices, no respective studies have thus far been reported on child dentifrices.

Material and methods

Seventeen commercial dentifrices for children up to 12 years of age were evaluated with respect to their in vitro cytotoxicity on gingival fibroblasts, oral squamous cell carcinoma HSC-2 cells, and L929 mouse fibroblasts. Proliferation was analyzed and live-dead staining was performed.

Results

Ten child dentifrices greatly reduced cell viability with LC50 values below 5 %. Four dentifrices showed a moderate cytotoxicity with LC50 values between 5 and 20 %. Three child dentifrices showed almost no cytotoxicity with LC50 values above 95 %. The results of the assays for proliferation and live-dead staining supported these findings.

Conclusions

The different composition of the child dentifrices translated into a broad spectrum of in vitro cytotoxicity on cells of the oral cavity.

Clinical relevance

The in vitro data provide the scientific foundation for further in vivo research testing the clinical relevance of the present findings.

The effectiveness of a dentifrice without sodium lauryl sulphate on dental plaque and gingivitis - a randomized controlled clinical trial

OBJECTIVES

The purpose of the study was to evaluate the effect on dental plaque and gingivitis of a dentifrice without sodium lauryl sulphate (SLS) compared to two SLS-containing dentifrices.

MATERIAL AND METHODS

For this double-blind, parallel study, 90 volunteers having moderate gingival inflammation (≥40%) were randomly divided among three groups: one group using non-SLS dentifrice containing enzymes, colostrum and low concentrations of zinc and two control groups each using different SLS-containing dentifrices. Dental plaque scores (Turesky modification of Quigley & Hein) and gingivitis scores (Bleeding On Marginal Probing) were assessed at baseline, after 2 and 4 weeks.

RESULTS

Eighty-nine participants provided evaluable data. A slight decrease in gingivitis scores was observed for all groups over 4 weeks, which was statistically significant for the non-SLS group. Mean values for dental plaque scores did not show major differences over 4 weeks. For both parameters, no significant differences between groups could be observed at any time point. Patient appreciation was in favour of the SLS groups especially regarding the foaming effect.

CONCLUSION

No significant differences could be observed with respect to the effect on plaque and gingivitis between SLS-containing and SLS-free dentifrice containing enzymes, colostrum and low concentration zinc. Patients enjoyed the duration of taste and the 'foaming effect' of SLS-containing dentifrices better.

Relationship between toothpastes properties and patient-reported discomfort: crossover study

OBJECTIVES

This study aims to correlate patient-reported reactions with in vitro analyses of the pH, abrasive quality, and cytotoxicity of four toothpastes.

MATERIALS AND METHODS

One hundred twenty-one patients received non-identified samples of toothpaste to be used for 6 days and answered a questionnaire about their sensations. In vitro analysis: the pH of toothpastes was measured with a pH meter. The abrasivity of toothpastes was evaluated against composite resin specimens (n = 10). A toothbrushing machine was used to simulate wear, which was indirectly measured by mass loss using a scale. Cell culture media conditioned with toothpaste were used to assess the cytotoxicity. Confluent cells were kept in contact with the conditioned media or control for 24 h. The cell viability was measured using the 3-(bromide, 4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium (MTT)-reduction assay. The obtained data on the pH, weight loss, and cell viability were compared by ANOVA/Tukey's tests (p < 0.05).

RESULTS

With the exception of the bleaching effect paste, the Oral B® paste produced the highest frequencies of irritation reports, tooth sensitivity, taste discomfort, and texture discomfort in the clinical study; patients also reported rougher teeth, soft tissue peeling, dry mouth, thrush, tingling, and taste changes in response to this paste. The in vitro analysis demonstrated that Oral B® had the lowest pH, the highest abrasivity, and produced the lowest cell viability (p < 0.01).

CONCLUSION

Results suggest that low pH toothpastes that are highly abrasive and cytotoxic may cause undesirable reactions in patients.

CLINICAL RELEVANCE

Toothpaste's properties should be well known for indication to patient therefore minimizing discomfort reports.

In vitro assessment of a toothpaste range specifically designed for children

OBJECTIVE

To evaluate the ability of a range of low abrasivity experimental toothpastes designed for use by children at different stages of their development (typically ages 0-2 years, 3-5 years and 6+ years) to promote fluoride uptake and remineralisation of artificial caries lesions.

METHODS

pH cycling study: demineralised human permanent enamel specimens were subjected to a daily pH cycling regime consisting of four 1-minute treatments with toothpaste slurries, a 4-hour acid challenge and remineralisation in pooled whole human saliva. Surface microhardness (SMH) was measured at baseline, 10 days and 20 days, and the fluoride content determined at 20 days. Enamel Fluoride Uptake (EFU): these studies were based on Method #40 described in the US Food and Drug Administration (FDA) testing procedures. Abrasivity: relative enamel abrasivity (REA) and relative dentine abrasivity (RDA) were measured using the Hefferren abrasivity test. Bioavailable fluoride: the bioavailable fluoride was determined for all experimental toothpastes from slurries of one part toothpaste plus 10 parts deionised water.

RESULTS

Enamel remineralisation measured by changes in SMH correlated with enamel fluoride content. A statistically significant fluoride dose response was observed for all toothpastes tested across all age groups (P < 0.05). The fluoride content of specimens in the pH cycling model correlated with the EFU testing results. The enamel and dentine abrasivities were low and the level of bioavailable fluoride was high for all experimental toothpastes.

CONCLUSION

A series of low abrasivity experimental toothpastes were developed which were effective at promoting fluoride uptake and remineralisation of artificial caries lesions.