The effect of toothpaste containing triclosan on oral mucosal desquamation. A model study

In vitro cytotoxicity (irritant potency) of toothpaste ingredients

PURPOSE

This study aimed to determine the cytotoxicity (irritant potency) of toothpaste ingredients, of which some had known to have sensitizing properties.

MATERIALS

From the wide variety of toothpaste ingredients, Xylitol, Propylene glycol (PEG), Sodium metaphosphate (SMP), Lemon, Peppermint, Fluoride, Cinnamon, and Triclosan and Sodium dodecyl sulphate (SDS) have been selected for evaluation of their cytotoxic properties.

METHODS

Reconstructed human gingiva (RHG) were topically exposed to toothpaste ingredients at different concentrations. The compound concentration resulting in 50% cell death (EC50) and 10% cell death (EC10) was determined by the MTT assay. Detrimental effects in tissue histology were observed by hematoxylin & eosin staining of tissue sections followed by microscopy.

RESULTS

While Xylitol, PEG, and SMP did not appear to affect cell viability or tissue histology, the concentrations of Lemon, Peppermint, Cinnamon and SDS present in toothpastes exceeded the EC50 value and resulted in clear detrimental effects in tissue histology, indicating that they could harm the oral mucosa. Triclosan and Fluoride concentrations in the tested toothpastes exceeded the EC10 value but remained below the EC50 value with no clear detrimental effects in tissue histology.

CLINICAL SIGNIFICANCE

Manufacturers are encouraged to comply with higher standards of quality and safety for toothpaste.

Histopathologic Spectrum of Intraoral Irritant and Contact Hypersensitivity Reactions: A Series of 12 cases

BACKGROUND

Irritant contact stomatitis (ICS) and contact hypersensitivity stomatitis (CHS) are often caused by alcohol, flavoring agents and additives in dentifrices and foods, and contactants with high or low pH. A well-recognized contactant for ICS is Listerine™ mouthwash, while that for CHS is cinnamic aldehyde. However, many other flavoring agents and even smokeless tobacco are contactants that cause mucosal lesions that are entirely reversible. The objective of this study is to 1) present cases of ICS and CHS with a clear history of a contactant at the site and the histopathologic features of the resulting lesion and 2) define the histopathologic features that characterize such lesions.

METHODS

12 cases of ICS and CHS with known contactants that exhibited distinct histopathologic patterns were identified.

RESULTS

ICS are characterized by three patterns in increasing order of severity namely: 1) superficial desquamation, 2) superficial keratinocyte edema, and 3) keratinocyte coagulative necrosis with/out spongiosis and microabscesses. CHS is characterized by two patterns namely plasma cell stomatitis with an intense plasma cell infiltrate and a lymphohistiocytic infiltrate with or without non-necrotizing granulomatous inflammation. Three patterns of the latter are recognized: (1) lymphohistiocytic infiltrate at the interface with well-formed or loosely aggregated non-necrotizing granulomas; (2) lymphohistiocytic infiltrate at the interface with peri- and para-vascular lymphohistiocytic nodules; and (3) lymphohistiocytic infiltrate at the interface with peri- and para-vascular lymphohistiocytic nodules containing non-necrotizing granulomas. The same contactant may elicit ICS and CHS, while one histopathologic pattern may be brought on by various contactants.

CONCLUSION

ICS and CHS have distinct histologic patterns. Recognizing that these patterns are caused by contactants would help clinicians manage such mucosal lesions.

Toothpastes with Enzymes Support Gum Health and Reduce Plaque Formation

Enzymes in toothpastes can support host immune responses, and thus maintain oral health. This study aimed to investigate gingival health and the plaque-reducing effects of enzyme-containing toothpastes. A laboratory study tested the antimicrobial potential of different enzyme-containing toothpaste formulations. Two promising formulations (enzyme-containing toothpastes with glucose oxidase and D-glucose with (C+) and without Citrox (C-) Citrox) were investigated in a clinical crossover trial (two slurries: sodium lauryl sulfate-containing (SLS), a toothpaste without SLS (reference), and water). Subjects (n = 20) abstained from toothbrushing for four days and rinsed with a toothpaste slurry. Bleeding on probing (BOP) and plaque indices (PI) were measured. A mixed linear model was used to statistically compare the slurries with respect to BOP and PI change. The in vitro bacterial growth-inhibiting evaluation showed the best results for SLS, followed by C+ and C-. The change in BOP and PI exhibited statistically significant differences to water rinsing (BOP; PI changes in % points (difference of the baseline and post-rinse values: water = 8.8%; 90.0%; C+ = -1.4%; 80.4%; SLS = 1.5%; 72.1%; reference = 0.8%; 77.5%; C- = -1.8%; 75.1%). All slurries exhibited anti-gingivitis and anti-plaque effects, resulting in a prophylactic benefit for limited-access regions during brushing.

A randomised clinical study comparing the effect of Steareth 30 and SLS containing toothpastes on oral epithelial integrity (desquamation)

OBJECTIVE

To compare the clinical effect of toothpastes containing Steareth 30 and SLS (sodium lauryl sulphate) surfactants on oral epithelial integrity (desquamation) using a new Oral Mucosal Sloughing Index (OMSI).

METHODS

30 volunteers participated in a single centre, double-blind, randomised, crossover clinical study. After a lead-in, subjects were allocated to the first test toothpaste, which was applied to the maxilla via a cap splint, followed by whole mouth brushing with the respective toothpaste and rinsing with the toothpaste slurry. Soft desquamation (lesion status) was assessed using a novel Oral Mucosal Sloughing Index (OMSI). Soft tissue status was measured at baseline (prior to test product use), 30 min following test product application and 4 days later following "at home" use of test toothpaste. After a wash out period, soft tissue assessment and product use were repeated for the remaining toothpaste.

RESULTS

Using the OMSI, 30 min post-application, significantly fewer lesion counts (all sites) were observed for the Steareth 30 toothpaste compared to SLS toothpaste (p < 0.0001). Additionally, 30 min after toothpaste use, the average lesion severity score was significantly lower for the Steareth 30 toothpaste compared to SLS toothpaste (p < 0.0001). There were no significant differences in lesion status at baseline or following 4 days of "at home" use of the toothpastes. No product related adverse events were reported.

CONCLUSION

Using an Oral Mucosal Sloughing Index for assessment, application of a toothpaste containing Steareth 30 generated significantly less transient soft tissue desquamation (fewer lesion counts and lower severity) than a toothpaste containing SLS.

CLINICAL SIGNIFICANCE

Treatment with a toothpaste containing Steareth 30 surfactant generated fewer transient soft tissue lesions (lower desquamation) compared to a toothpaste containing SLS surfactant.

Oral mucosal peeling related to dentifrices and mouthwashes: A systematic review

Background

The aim of this systematic review was to summarise the clinical information available about oral mucosal peeling (OMP) and to explore its aetiopathogenic association with dentifrices and mouthwashes.

Material and Methods

PICOS outline: Population: subjects diagnosed clinically and/or pathologically. Intervention: exposition to oral hygiene products. Comparisons: patients using products at different concentrations. Outcomes: clinicopathological outcomes (primary) and oral epithelial desquamation (secondary) after use. Study design: any. Exclusion criteria: reports on secondary or unpublished data, in vitro studies. Data were independently extracted by two reviewers.

Results

Fifteen reports were selected from 410 identified. Descriptive studies mainly showed low bias risk, experimental studies mostly an “unclear risk”. Dentifrices or mouthwashes were linked to OMP, with an unknown origin in 5 subjects. Sodium lauryl-sulphate (SLS) was behind this disorder in 21 subjects, tartar-control dentifrices in 2, and flavouring agents in 1 case. Desquamation extension was linked to SLS concentration. Most cases were painless, leaving normal mucosa after desquamation. Tartar-control dentifrices caused ulcerations more frequently.

Conclusions

OMP management should consider differential diagnosis with oral desquamative lesions, particularly desquamative gingivitis, with a guided clinical interview together with pathological confirmation while discouraging the use of the product responsible for OMP.

Key words:Systematic review, oral mucosal peeling, dentifrices, sodium lauryl-sulphate, oral hygiene products.

Triclosan: An Update on Biochemical and Molecular Mechanisms

Triclosan (TCS) is a synthetic, chlorinated phenolic antimicrobial agent commonly used in commercial and healthcare products. Items made with TCS include soaps, deodorants, shampoos, cosmetics, textiles, plastics, surgical sutures, and prosthetics. A wealth of information obtained from in vitro and in vivo studies has demonstrated the therapeutic effects of TCS, particularly against inflammatory skin conditions. Nevertheless, extensive investigations on the molecular aspects of TCS action have identified numerous adversaries associated with the disinfectant including oxidative injury and influence of physiological lifespan and longevity. This review presents a summary of the biochemical alterations pertaining to TCS exposure, with special emphasis on the diverse molecular pathways responsive to TCS that have been elucidated during the present decade.

Frictional Keratosis, Contact Keratosis and Smokeless Tobacco Keratosis: Features of Reactive White Lesions of the Oral Mucosa

White lesions of the oral cavity are quite common and can have a variety of etiologies, both benign and malignant. Although the vast majority of publications focus on leukoplakia and other potentially malignant lesions, most oral lesions that appear white are benign. This review will focus exclusively on reactive white oral lesions. Included in the discussion are frictional keratoses, irritant contact stomatitis, and smokeless tobacco keratoses. Leukoedema and hereditary genodermatoses that may enter in the clinical differential diagnoses of frictional keratoses including white sponge nevus and hereditary benign intraepithelial dyskeratosis will be reviewed. Many products can result in contact stomatitis. Dentrifice-related stomatitis, contact reactions to amalgam and cinnamon can cause keratotic lesions. Each of these lesions have microscopic findings that can assist in patient management.

Triclosan inhibits tumor necrosis factor-alpha-stimulated urokinase production in human gingival fibroblasts

BACKGROUND AND OBJECTIVES

Destruction of the supporting periodontal tissues is mediated by the action of several proteolytic enzymes. Urokinase is a serine protease that plays a key role in connective tissue destruction through conversion of plasminogen into plasmin. The present study was conducted to evaluate the effect of triclosan on the production and activity of urokinase in cultured gingival fibroblasts.

MATERIAL AND METHODS

Urokinase production was studied in primary cultures of human gingival fibroblasts stimulated with tumor necrosis factor-alpha. Urokinase activity and production were evaluated using casein zymography and western blotting, respectively. Urokinase mRNA expression was evaluated using the reverse transcription-polymerase chain reaction. Triclosan was used to interfere with this stimulatory effect. The roles of different cell-signaling cascades involved in urokinase production were assessed through western blotting and immunofluorescence using several cell-signaling inhibitors.

RESULTS

Tumor necrosis factor-alpha was found to be a strong stimulus for urokinase production and triclosan was able to inhibit this response at the protein and mRNA levels. Triclosan was also able to inhibit conversion of plasminogen into plasmin. Tumor necrosis factor-alpha-stimulated urokinase production was shown to be dependent on the nuclear factor-kappaB and c-Jun N-terminal kinase signaling pathways. Triclosan inhibited c-Jun N-terminal kinase phosphorylation and c-Jun production.

CONCLUSIONS

Within the limits of this study, these results show that triclosan may inhibit urokinase production and plasminogen activation in gingival fibroblasts through modulation of the c-Jun N-terminal kinase signaling pathway.

Substantivity of amine fluoride/stannous fluoride following different modes of application: a randomized, investigator-blind, placebo-controlled trial

OBJECTIVE

Amine fluoride/stannous fluoride (ASF) is proven to be effective against plaque and gingivitis. The purpose of this clinical controlled study was to investigate the influence of different application modes on the substantivity of this formulation.

MATERIAL AND METHODS

Seventeen healthy volunteers received a professional dental prophylaxis. Undisturbed plaque growth was permitted for the next 48 h. In a crossover design, participants received ASF as a single mouthrinse, toothpaste, slurries with high (HA) or low (LA) air content, or a placebo. Vitality of plaque bacteria was investigated before and at 1, 2, 3, 4, 6, and 8h after application of ASF. ANOVA was applied on a 0.05 significance level.

RESULTS

Highest reduction of plaque vitality resulted after toothpaste application, followed by mouthrinse, LA, and HA slurry. No changes occurred in the placebo group. Compared to baseline and placebo, statistically significant changes were detected up to 4h in all ASF groups. Toothpaste exerted antibacterial efficacy up to 8h. Vitality reduction was higher in the LA group than in the HA group.

CONCLUSIONS

The concentration of ASF in formulations influences the time course of the antibacterial effect. Contact of ASF formulations with air might reduce their efficacy.

Antibacterials as anti-inflammatory agents: dual action agents for oral health

BACKGROUND

Inflammatory processes with a range of specialized cells and biochemical mediators form a complex network of inter-related signal transducing pathways that relay information to preserve normal functions. Advances in molecular analyses of the information relay pathways for their constituents and principal ligands along with mechanisms utilized by the host for microbial recognition have stimulated interest in therapeutic agents with dual functionalities i.e. antibacterial and anti-inflammatory effects.

AIM

This review examines clinically tested agents for oral health applications with both antimicrobial and anti-inflammatory effects to include antibiotics, antimicrobials and phenolics.

RESULTS

Bis-phenols such as triclosan, representing a unique dual functional therapeutic for routine oral hygiene, with its demonstrated clinical effects on inhibiting the dental plaque biofilm, reducing inflammation (gingivitis) and subsequent periodontitis is described. Cyclines, comprising another class of approved anti-inflammatory agents used at the patient level for oral health is discussed. Dual active agents in current clinical practice for systemic conditions are highlighted to summarize the clinical validity of dual function agents as an emerging therapeutic strategy.

CONCLUSIONS

Clinical studies demonstrate therapeutic benefits of agents with dual functionality with their effects on microorganisms and the concomitant host inflammatory response. Advances in microbial pathogenesis and resultant inflammation will facilitate progress in this emerging area poised to be a significant milestone for dental therapeutics.

A study into the plaque-inhibitory activity of experimental toothpaste formulations containing antimicrobial agents

BACKGROUND/AIMS

The use of specific antimicrobial agents in toothpastes may help reduce plaque and gingivitis. There would also appear to be some value in formulating products that contain combinations of such agents that may potentiate any activity present. The aims of this exploratory and pragmatic study were twofold: (1) Exploratory: to compare the effects on plaque re-growth of two zinc citrate/triclosan formulations, one of which contained bromochlorophene and hence demonstrate any additional beneficial effects produced by the addition of the phenol. (2) Pragmatic: to assess whether both pastes were significantly better than a benchmark control, proprietary fluoride toothpaste at inhibiting plaque formation.

METHODS

Following an initial prophylaxis to remove all plaque and calculus, toothpaste slurry rinses were used over a 96 h period by 24 volunteers, while omitting all other oral hygiene procedures. After 24, 48 and 96 h, plaque was measured by plaque area and by plaque index. For comparative purposes, a conventional commercial fluoride toothpaste rinse was also used as a benchmark control in this triple cross-over double-blind study.

RESULTS

With one exception, comparisons between the three pastes failed to show any significant differences in plaque accumulation at 96 h whether assessed by plaque index or area. At this time period, significantly more plaque was seen with the zinc citrate paste without bromochlorophene, compared with that of the control paste.

CONCLUSIONS

The findings from this study failed to demonstrate a plaque-inhibitory action from the two novel formulations beyond that of a conventional benchmark toothpaste, although overall levels of plaque formed by the volunteers, especially on the control paste were generally lower than in previous studies. Nevertheless, it remains to be determined whether the test formulations could exert a direct anti-inflammatory action against gingivitis by way of the triclosan delivery system. Neither test formulation was subsequently marketed.

Triclosan reduces microsomal prostaglandin E synthase-1 expression in human gingival fibroblasts

OBJECTIVE

The effect of triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) on the expression of cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) and on the translocation of the nuclear factor-kappaB (NF-kappaB) in relation to prostaglandin E2 (PGE2) production was investigated in human gingival fibroblasts challenged with tumor necrosis factor alpha (TNFalpha).

METHODS

Fibroblasts were established from gingival biopsies obtained from six children. COX-2 mRNA and protein expression was quantified using mRNA quantitation and enzyme immunometric assay kits. mPGES-1 mRNA was analysed by RT-PCR, mPGES-1 protein and NF-kappaB translocation by immunoblotting. PGE2 was determined by radioimmunoassay.

RESULTS

The cytokine TNFalpha enhanced the expression of mRNA as well as the protein levels of both COX-2 and mPGES-1 and subsequently the production of PGE2 in gingival fibroblasts. Treatment of gingival fibroblasts with triclosan (1 microg/ml) significantly reduced the stimulatory effect of TNFalpha (10 ng/ml) on the expression of mPGES-1 at both the mRNA and the protein level by an average of 21% and 43%, respectively, and subsequently the production of PGE2 (p<0.01). Triclosan did not, however, affect the translocation of NF-kappaB or the expression of COX-2 in TNFalpha-stimulated cells.

CONCLUSION

The results show that triclosan reduces the augmented biosynthesis of PGE2 by inhibiting the mRNA and the protein expression of mPGES-1 in gingival fibroblasts. This finding may partly explain the anti-inflammatory effect of the agent previously reported in clinical studies.

Formulation ingredients for toothpastes and mouthwashes

In order to achieve the multi-claim products required for the dental care category, it is necessary for the formulator to use a variety of different ingredients. This places a number of demands on the development process. Innovations in the areas of pharmaceutical technology have contributed to the formulation of the products having superior efficacy as well as other attributes that may contribute to clinical response and patient acceptability. Improved clinical efficacy and tolerability, along with conditioning signals, should encourage patient compliance with oral hygiene further complementing professional efforts directed at disease prevention. The most effective way of preventing the development of dental disease is in controlling the production of dental plaque. It is formed by microbial action. The removal of plaque from the teeth and related areas is essential for the maintenance of a healthy mouth. In this paper we have presented the main components of toothpastes and mouthwashes. For the active ingredients, their supposed effect as therapeutic agents is also explained.

Uptake, distribution and release of 14C-triclosan in human gingival fibroblasts

Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) is an antibacterial agent included in dentifrices and mouth rinses. Previously, we reported that triclosan reduces the production of the inflammatory mediators in gingival fibroblasts. The aim of this study was to investigate the uptake, distribution, and release of (14)C-triclosan in gingival fibroblasts. Time-course studies showed that the uptake of (14)C-triclosan in cytoplasmic and nuclear fraction started within the first minute of incubation, increased gradually, and reached constant levels after 1 h in the nuclear fraction and slightly increased in the cytoplasmic fraction between 3 and 24 h. The distribution of (14)C-triclosan in the cytoplasmic and the nuclear fractions was, on an average, 84 and 16%, respectively. Autoradiographic results based on transmission electron microscopy confirmed the distribution of (14)C-triclosan in the cytoplasm and nucleus of the cell. The release of (14)C-triclosan showed that the radioactivity of the agent in the medium gradually increased during the first hour of incubation and then reached steady-state levels. After repeated washing of preloaded fibroblasts, the level of (14)C-triclosan in the cytoplasmic fraction decreased by 77% whereas the level in the nuclear fraction remained unchanged. Our results demonstrate that triclosan is distributed in the cytoplasm and remains associated with the nucleus of gingival fibroblasts, suggesting that the agent may affect the intracellular signal pathways involved in the production of inflammatory mediators.

The effect of sodium lauryl sulphate, triclosan and zinc on the permeability of normal oral mucosa

OBJECTIVE

Sodium lauryl sulphate (SLS), an important component in many oral health products, is well established as a contact irritant in skin. Recent studies have suggested that it may also affect the structural integrity of oral mucosa. SLS is rarely used alone in dentifrices or mouthwashes and the aim of this study was to establish the effect of SLS both alone and in combination with Triclosan (TCN) and zinc (Zn) on the permeability barrier properties of normal human oral mucosa.

METHOD

Ventral tongue mucosa was obtained from nine males and seven females within 60 h of death and stored frozen at -70 degrees C until use. The permeability of the tissue to tritiated water was measured after pretreatment for 15 min with SLS alone, SLS/TCN, SLS/Zn and a SLS/TCN/Zn mixture. Treatment with distilled water (DW) served as control. The histological appearance of the tissue before and after treatment was also examined by light microscopy.

RESULTS

SLS treatment caused a significant increase in water permeability compared to control tissue (Kp = 11.7 +/- 1.00; 4.96 +/- 0.50 respectively; P < 0.005). Treatment with a SLS/TCN/Zn mixture, however, had no effect on the permeability to water (Kp = 5.5 +/- 0.56). Histological examination revealed that tissue exposed to SLS had a marked disruption of the epithelial surface whilst tissue treated with a SLS/TCN/Zn mixture was indistinguishable from controls.

CONCLUSION

Although mucosa exposed to SLS alone showed an increase in permeability to water, the addition of TCN and Zn to SLS appeared to prevent this effect. As SLS is included in some dental products to solubilise compounds such as TCN, its presence may have no effect on the permeability barrier property of oral mucosa.

Clinical implications of the dry mouth. Oral mucosal diseases

Salivary hypofunction caused by salivary gland disease, medication, or radiation may predispose for secondary oral mucosal diseases. In these patients the protective coating of saliva is reduced or absent, leaving the oral mucosa more vulnerable. Candidiasis, burning mouth syndrome, and white lesions of the oral mucosa are increased in frequency. The aim of management is to prevent oral pathological changes. The management procedure may include proper oral hygiene, saliva-stimulating agents, or saliva substitutes, depending on the severity of the salivary dysfunction. Treatment includes antifungal therapy if candidiasis is diagnosed. In severely distressed patients, local or systemic corticosteroids may be indicated. Precautions, like refraining from smoking and avoiding toothpastes containing sodium lauryl sulfate, should also be taken. In the future, agents combining antibacterial and antiinflammatory actions, like triclosan, may show promising effects in patients with oral mucosal diseases secondary to salivary hypofunction.

The influence of triclosan, zinc or propylene glycol on oral mucosa exposed to sodium lauryl sulphate

Previous studies on triclosan treatment of skin exposed to sodium lauryl sulphate (SLS) indicated a protective rôle of zinc and an irritant effect of propylene glycol (PG). The aim was hence to examine whether zinc or PG also may affect SLS-induced oral mucosal reactions, and also to test the influence of zinc in combination with triclosan. 15 healthy dental students participated in this double-blind crossover study performed in 2 experimental series. They were rinsing 2x daily with solutions containing (A) 1.5% SLS, (B) 1.5% SLS/0.5% zinc citrate and (C) 1.5% SLS/PG (1:8) in experiment 1, and (D) 1.5% SLS/0.15% triclosan/0.3% zinc citrate and (E) 1.5% SLS/0.15% triclosan in experiment 2. Clinical evaluation by 2 examiners of degree of erythema and oral mucosal desquamations was then performed. The critical micellar concentration was also determined. SLS and SLS/PG, which were not different in effect, evoked significantly more erythematous reactions than SLS/Tri/Zn. This solution was numerically but not statistically better than SLS/Tri, and the latter also did lead to significantly less erythema than SLS/PG. In conclusion, the present study revealed no irritation of the oral mucosa due to PG, whereas a protective effect of zinc as well as the anti-inflammatory effect of triclosan were confirmed.

Skin reactions and irritation potential of four commercial toothpastes

Skin reactions to 4 toothpastes were tested in 19 healthy dental students in a double-blind study. The hypothesis was that common toothpaste brands with and without sodium lauryl sulfate (SLS) and triclosan and with different additives/emulgators differ in irritation potential. An occlusion test system on human skin was used. The toothpastes tested were A) Zendium (non-ionic detergent), B) Solidox F (SLS/polyethylene glycol), C) Colgate Total (triclosan/copolymer/SLS/propylene glycol), and D) Solidox G (triclosan/zinc citrate/SLS/polyethylene glycol). Toothpaste C was the greatest irritant, causing skin erythema in 16 of the 19 subjects, whereas toothpaste D gave no reactions. Toothpaste B provoked three reactions (two severe), whereas toothpaste A caused only one mild reaction. Although this study was carried out on skin and hence not directly applicable to the oral cavity, these and previous results may indicate that a toothpaste without propylene glycol and SLS may be preferred by susceptible persons.