In vitro effects of ethanol and mouthrinse on permeability in an oral buccal mucosal tissue construct

In vitro permeation of nicotine and tobacco specific nitrosamines from smokeless tobacco product extracts in a 3D buccal tissue model

Tobacco product use is a risk factor in the development of oral cancer, although epidemiology studies show this risk is far less with smokeless tobacco product use than cigarette smoking. While smokeless tobacco contains harmful and potentially harmful constituents (HPHCs), the oral permeation of HPHCs in oral tobacco products is not completely understood. To improve the understanding, three different extract concentrations of the CORESTA reference products (CRP) for snus (CRP1.1) and moist snuff (CRP2.1) were applied to cellular tissue derived from two donors of EpiOral™ model, a 3D human buccal model, and permeation of nicotine and tobacco-specific nitrosamines (TSNAs) were measured over two hours. Permeation of 0.15% caffeine in complete artificial saliva and cell viability were also measured. Results showed that a consistent and concentration dependent cumulative permeation of nicotine and TSNAs was observed with high percent recovery in all conditions. A high degree of sensitivity was seen for all analytes, with minimal cytotoxicity for both CRPs. The data presented here show the EpiOral™ model is fit-for-purpose to evaluate the permeation of nicotine and TSNAs in nicotine-containing snus and moist snuff oral tobacco.

Development of an oral mucosal irritation test using a three-dimensional human buccal oral mucosal model

The oral mucosa can become irritated by oral care products and lip cosmetics. Therefore, it is important to determine the irritation potential of their ingredients and products during safety evaluations. We developed a method for oral mucosal irritation test using EpiOral, which is a three-dimensional cultured model. Exposure of sodium lauryl sulphate (SLS) to EpiOral showed a dose-dependent decrease in cell viability. Under 120 min exposure conditions, SLS irritation was detected when 60% cell viability was set as a criterion. Evaluation of the irritancy of SLS and four other raw materials used in oral products at three laboratories under the above conditions confirmed good transferability of the test. Focused on the similarity of the oral and eye mucous, 32 chemicals categorised by the UN-GHS eye-irritation classification were evaluated to ensure the reliability of our criteria at these laboratories. The concordance rate between the UN-GHS classification and our test results was 100% for irritants and 60% for non-irritants. The good intra-laboratory reproducibility of our test was confirmed from the evaluation results of negative and positive controls, and the good inter-laboratory reproducibility was confirmed from the results of 32 chemicals. These findings showed that oral mucosal irritation can be evaluated using EpiOral.

Oral Absorption across Organotypic Culture Models of the Human Buccal Epithelium after E-cigarette Aerosol Exposure

Inhaled aerosols are absorbed across the oral cavity, respiratory tract, and gastrointestinal tract. The absorption across the oral cavity, which is one of the exposure routes, plays an important role in understanding pharmacokinetics and physiological effects. After aerosol exposure from e-cigarettes, tissue viability studies, morphological observation, and chemical analyses at the inner and outer buccal tissues were performed using organotypic 3D in vitro culture models of the buccal epithelium to better understand the deposition and absorption on the inner and outer buccal tissues. The aerosol exposures did not affect the tissue viability and had no change to the tissue morphology and structure. The deposition ratio at the buccal tissue surface is relatively low. This shows that majority of aerosol transfers to the airway tissues. The distribution from the inner tissue to the outer tissue has selectivity among various compounds, depending on the affinity with the liquid crystal structure of phospholipids and glucosylceramide. Although nicotine absorption in the aqueous solution was well known to increase as the unprotonated state of nicotine increased, the nicotine absorption after the aerosol exposure is irrelevant to the protonated-unprotonated state. Furthermore, the results showed that half of nicotine that adhered to the oral cavity transferred to the inner tissue via the oral epithelium and the other half transferred to the gastrointestinal tract accompanying multiple executions of swallowing, while majority of the water-soluble compounds with the hydroxyl group such as propylene glycol and benzoic acid that adhered to the oral cavity were eluted with the saliva and transferred to the gastrointestinal tract by swallowing.

Buccal films: A review of therapeutic opportunities, formulations & relevant evaluation approaches

The potential of the mucoadhesive film technology is hard to ignore, owing to perceived superior patient acceptability versus buccal tablets, and significant therapeutic opportunities compared to conventional oral drug delivery systems, especially for those who suffer from dysphagia. In spite of this, current translation from published literature into the commercial marketplace is virtually non-existent, with no authorised mucoadhesive buccal films available in the UK and very few available in the USA. This review seeks to provide an overview of the mucoadhesive buccal film technology and identify key areas upon which to focus scientific efforts to facilitate the wider adoption of this patient-centric dosage form. Several indications and opportunities for development were identified, while discussing the patient-related factors influencing the use of these dosage forms. In addition, an overview of the technologies behind the manufacturing of these films was provided, highlighting manufacturing methods like solvent casting, hot melt extrusion, inkjet printing and three-dimensional printing. Over thirty mucoadhesive polymers were identified as being used in film formulations, with details surrounding their mucoadhesive capabilities as well as their inclusion alongside other key formulation constituents provided. Lastly, the importance of physiologically relevant in vitro evaluation methodologies was emphasised, which seek to improve in vivo correlations, potentially leading to better translation of mucoadhesive buccal films from the literature into the commercial marketplace.

Permeability of Buccal Mucosa

The buccal mucosa provides an alternative route of drug delivery that can be more beneficial compared to other administration routes. Although numerous studies and reviews have been published on buccal drug delivery, an extensive review of the permeability data is not available. Understanding the buccal mucosa barrier could provide insights into the approaches to effective drug delivery and optimization of dosage forms. This paper provides a review on the permeability of the buccal mucosa. The intrinsic permeability coefficients of porcine buccal mucosa were collected. Large variability was observed among the published permeability data. The permeability coefficients were then analyzed using a model involving parallel lipoidal and polar transport pathways. For the lipoidal pathway, a correlation was observed between the permeability coefficients and permeant octanol/water partition coefficients (Kow) and molecular weight (MW) in a subset of the permeability data under specific conditions. The permeability analysis suggested that the buccal permeation barrier was less lipophilic than octanol. For the polar pathway and macromolecules, a correlation was observed between the permeability coefficients and permeant MW. The hindered transport analysis suggested an effective pore radius of 1.5 to 3 nm for the buccal membrane barrier.

Efficacy and safety evaluation of alcohol-containing and alcohol-free mouth rinses: A clinicocytological study

Context:

Whether the alcohol-based mouth rinses are as good as nonalcoholic mouth rinses as far as oral mucosal safety is concerned?

Aims:

The aim of the study was to investigate the oral mucosal safety of widely used alcohol- and nonalcohol-based mouth rinses at their recommended doses.

Settings and Design:

The clinical and cytological investigations were carried out by enrolling 120 systemically healthy volunteers fulfilling the inclusion criteria. The volunteers were subjected to a repeated mouth rinse for 60 days to either alcohol-based or alcohol-free mouth rinses at their recommended dosages. A comparative analysis for any clinical adverse response on the oral mucosa and efficacy, i.e., reduction of plaque and gingival index was done at the terminal of the exposure. The studies were also carried out to investigate the cytotoxicity and genotoxicity potential of alcohol-based and alcohol-free mouth rinses in the exposed mucosal cells.

Subjects and Methods:

The data have been presented in comparative account between alcohol-based and alcohol-free mouth rinses in the volunteers at day 0 and day 60. The cytotoxicity and genotoxicity potential of prescribed doses of alcohol- and alcohol-free mouth rinses have also been evaluated using tetrazolium bromide salt 3-(4, 5-dimethylthiazol-2-yl)-2,-diphenyl tetrazolium bromide, neutral red uptake, and trypan blue dye, micronucleus and chromosomal aberrations.

Results:

The study findings reveal no statistically as well as biologically significant adverse responses of both alcohol-based and alcohol-free mouth rinses at clinical and cytological level.

Conclusions:

Under cytological observation, repeated dose exposure up to 60 days of the mouth rinses (alcohol-based and alcohol-free) used in the study was found to be effective and safe at their prescribed dosages.

In vitro three-dimensional organotypic culture models of the oral mucosa

Three-dimensional, organotypic models of the oral mucosa have been developed to study a wide variety of phenomena occurring in the oral cavity. Although a number of models have been developed in academic research labs, only a few models have been commercialized. Models from academic groups offer a broader range of phenotypes while the commercial models are more focused on the oral and gingival mucosa. The commercialized models are manufactured under highly controlled conditions and meet the requirements of quality standards, which leads to high levels of reproducibility. These in vitro models have been used to evaluate the irritancy of oral care products such as toothpastes, mouthwashes, and mucoadhesives. The effects of cigarette smoke on oral cavity tissues have been studied and compared to those of e-cigarettes. Oral tissue models have facilitated investigation of the mechanisms of oral mucositis and oral candidiasis and have been used to examine transbuccal drug delivery rates and the absorption of nanoparticles. Infection studies have investigated the effects of HIV-1 along with the effects of commensal and pathogenic bacteria. More recently, a differentiated oral tissue model has been shown to express the ACE2 receptor, which is known to be important for the receptor-mediated entry of the SARS-CoV-2 coronavirus into human cells and tissues. Hence, oral mucosal models may find application in determining whether viral infection of the oral mucosa is possible and whether such infection has implications vis-a-vis the current COVID-19 pandemic. As is apparent, these models are used in a broad variety of applications and often offer advantages versus animal models in terms of reproducibility, avoiding species extrapolation, and the ethical concerns related to human and animal experimentation. The goals of this paper are to review commercially available models of the human buccal and gingival mucosa and highlight their use to gain a better understanding of a broad range of phenomena affecting tissues in the oral cavity.

Optimization of an oral mucosa in vitro model based on cell line TR146

During the last years, the popularity of saliva has been increasing for its applicability as a diagnostic fluid. Blood biomarker molecules have to cross the blood-saliva barrier (BSB) in order to appear in saliva. The BSB consists of all oral and salivary gland epithelial barriers. Within this context, the optimization of in vitro models for mechanistic studies about the transport of molecules across the oral mucosa is an important task. Here, we describe the optimization and comprehensive characterization of a Transwell model of the oral mucosa based on the epithelial cell line TR146. Through systematic media optimization investigating 12 different set-ups, a significant increase of barrier integrity upon airlift cultivation is described here for TR146 cell layers. The distinct improvement of the paracellular barrier was described by measurements of transepithelial electrical resistance (TEER) and carboxyfluorescein permeability assays. Histological characterization supported TEER data and showed a stratified, non-keratinized multilayer of the optimized TR146 model. High-Throughput qPCR using 96 selected markers for keratinization, cornification, epithelial-mesenchymal transition, aquaporins, mucins, tight junctions, receptors, and transporter proteins was applied to comprehensively characterize the systematic optimization of the cellular model and validate against human biopsy samples. Data revealed the expression of several genes in the oral mucosa epithelium for the first time and elucidated novel regulations dependent on culture conditions. Moreover, functional activity of ABC-transporters ABCB1 and ABCC4 was shown indicating the applicability of the model for drug transport studies. In conclusion, a Transwell model of the oral mucosa epithelium was optimized suitably for transport studies.

Evaluation of Clay-Functionalized Wafers and Films for Nicotine Replacement Therapy via Buccal Mucosa

The functional physicochemical properties of nicotine (NIC)-loaded composite freeze-dried wafers and solvent-evaporated films comprising hydroxypropylmethylcellulose (HPMC) and sodium alginate (SA), stabilized with magnesium aluminium silicate (MAS), have been reported. The formulations were characterized for swelling capacity, mucoadhesion, in vitro drug dissolution properties in simulated saliva (SS) and PBS at pH 6.8, and ex vivo and in vitro permeation using pig buccal mucosa membrane and EpiOralTM buccal tissue culture, respectively; finally, the cell viability of the EpiOralTM tissues after contact with the NIC-loaded formulations was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the functional characteristics compared with those of commercially available NIC strips. Swelling and NIC release from the HPMC⁻SA wafers were more prolonged (30 min) compared to the commercially available NIC strips which disintegrated rapidly and released the drug within 5 min. Generally, swelling, mucoadhesion, and drug release was faster in PBS than in SS, and the presence of MAS was essential for maintaining a high dose recovery compared to non-MAS formulations and commercial NIC strips, which showed lower percentage of NIC content, possibly due to evaporation during analysis. Permeation studies showed that the NIC released was able to cross both porcine buccal membrane and the EpiOralTM buccal tissue, with the latter showing higher permeation flux for all the formulations tested. All the NIC-loaded, MAS-stabilized formulations showed high tissue viability, with values above 80%, showing their great potential for use as buccal delivery platforms for NIC replacement therapy to aid smoking cessation.

Bleachorexia-an addictive behavior to tooth bleaching: a case report

Bleachorexia, addiction to tooth bleaching, is a behavioral disorder similar to anorexia. The patient feels that their teeth are always not white enough and continues to use whiteners to obtain a “perfect” smile. Such behavior falls under the category of a body dysmorphic disorder and may need medical counseling.

Effects of octenidine mouth rinse on apoptosis and necrosis of human fibroblasts and epithelial cells - an in vitro study

This study aimed at comparing the cytotoxicity of a new octenidine mouth rinse (MR) on gingival fibroblasts and epithelial cells using different established MRs. Octenidol (OCT), Chlorhexidine 0.2% (CHX), Meridol (MER), Oral B (OB), and control (PBS only) were used. Human primary gingival fibroblasts (HGFIBs) and human primary nasal epithelial cells (HNEPCs) were cultivated in cell-specific media (2 × 10⁵ cells/well) and treated with a MR or PBS for 1, 5, and 15 min. All tests were performed in duplicate and repeated 12 times. The apoptosis and necrosis were determined using a Caspase-3/7 assay and LDH assay, respectively. The data were analyzed using two-way analysis of variance with subsequent Mann-Whitney U-test. No significant differences could be found between the incubation times of the MR, neither for apoptosis nor necrosis (p > 0.05). Regarding apoptosis of HGFIBs, MRs had no influence at all. In HNEPCs, OCT induced relevantly lower apoptosis than CHX (p = 0.01). Considering necrosis, MER showed the lowest numbers of necrotic HGFIBs and HNEPCs, whereas OB induced the highest number of necrotic cells. The differences between both MR were statistically relevant (p < 0.01). OCT did neither differ from the other MRs nor from the control (PBS) in induction of necrosis in both cell types. In conclusion, the slightly negative effect of OCT considering apoptosis and necrosis of HGFIBs and HNEPCs is nearly the same or even lower compared to the established MRs included in this study. The results confirm that OCT is a potential alternative to CHX.

Evaluation of the Safety, Cell Migration, and Mucoadhesive Properties of a Mucoadhesive Polymer Blend in Human Oral Mucosa

The efficacy of active pharmaceutical ingredients (API) in compounded medications for oral mucosa greatly depends on the composition of the base. Here, we assessed the safety, facilitation of cell migration, and mucoadhesive properties of a newly developed mucoadhesive polymer blend (MPB) which contains pullulan, tamarindus indica polysaccharide, and sodium hyaluronate. No cell death was observed when human oral keratinocyte (HOK) and fibroblast (HOrF) cells were exposed to 1% MPB for 24 h. Epithelial cells in a 3D buccal tissue model (EpiOral) were unaffected when exposed to 50% MPB for 20 h whereas 1% Triton X-100 killed 93% cells after 4.5 h. The expressions of cytokines IL1α and IL1β and cell proliferation markers PCNA, CYCLIN A, and CYCLIN D1 in EpiOral tissue did not increase suggesting that MPB is neither an irritant nor a mitogen. Markers of apoptosis such as cleavage of CASPASES 8/9, upregulation of pro-apoptosis NOXA protein, and downregulation of anti-apoptosis XIAP protein were observed in Triton X-100-treated cells but not in cells exposed to MPB. The migration of HOK and HOrF cells was stimulated by MPB, and the expression of E-CADHERIN in the EpiOral tissues was unaffected. Moreover, MPB showed stronger mucoadhesion on the human EpiOral tissue model compared with a reference product. We conclude that MPB can safely deliver API within the oral mucosa, facilitate cell migration, and may increase drug efficacy through its strong mucoadhesive property.

In vitro Effect of Mouthrinse Containing Essential Oils on Proliferation and Migration of Gingival Epithelial Cells

We aimed to investigate in vitro the effects of mouthrinses containing essential oils (EOs) on proliferation and migration of gingival epithelial cells. Human gingival epithelial cells were treated with predetermined dilutions of commercially available EO mouthrinses with or without ethanol and a mouthrinse containing cetyl pyridinium chloride (CPC) for 60 s. Cell proliferation was evaluated using WST-1 assay. Cell migration was assessed using a wound closure model. Within 10 s of exposure to EO mouthrinse without ethanol, the epithelial cells became aberrant and shrank. No statistically significant difference in cell migration or proliferation was observed among cells pretreated by the EO mouthrinse with ethanol, CPC mouthrinse and control (phosphate buffered saline). In contrast, the EO mouthrinse without ethanol significantly reduced cell proliferation (p < 0.001) to approximately 20% relative to control. As for the EO mouthrinse without ethanol, it was not possible to assess its effect on cell migration using this model, because treated cells could be easily detached from the culture plate upon scratch, possibly because of the surfactant ingredient in the formulation. Within the limitations of the study, the EO mouthrinse with ethanol exerted no inhibitory effect on proliferation and migration of the gingival epithelial cells. Copyright © 2016 John Wiley & Sons, Ltd.

Randomized controlled trial on the efficacy of new alcohol-free chlorhexidine mouthrinses after 8 weeks

OBJECTIVES

To evaluate the efficacy of two alcohol-free antimicrobial mouthrinses in reducing plaque and gingivitis compared to an alcohol-containing rinse and toothbrushing alone.

METHODS

One hundred and sixty healthy volunteers were enrolled in the randomized controlled trial. Participants were randomly and equally assigned to four groups: (i) toothbrushing + rinsing (0.06% CHX + 0.025% NaF, alcohol-containing rinse, positive control); (ii) toothbrushing + rinsing (0.06% CHX + 0.025% NaF, alcohol-free experimental rinse); (iii) toothbrushing + rinsing (0.06% CHX + 0.03% CPC + 0.025% NaF, alcohol-free experimental rinse); (iv) toothbrushing alone (negative control). At baseline, Quigley-Hein plaque index (QHI), modified proximal plaque index (MPPI), and papillary bleeding index (PBI) were recorded. All subjects brushed their teeth as usual during the study. Additionally, groups 1-3 rinsed twice daily. Eight weeks after baseline, indices were recorded again. anova with Bonferroni adjustment served for statistical analysis.

RESULTS

One hundred and fifty-five participants were included into final analysis (i: n = 39, 2: n = 39, 3: n = 37, 4: n = 40). Experimental rinses (ii, iii) reduced QHI and MPPI to a higher extent than the negative control (iv), whereas no significant difference to the positive control was found. QHI: (i) 36.6%, (ii) 32.3%, (iii) 36.8%, (iv) 21.6%; MPPI: (i) 11.9%, (ii) 12.2%, (iii) 13.6%, (iv) 3.5%. For PBI, no statistically significant difference was found between groups: (i) 80.2%, (ii) 77.8%, (iii) 76.5% and (iv) 78.8%.

CONCLUSIONS

With respect to QHI and MPPI, toothbrushing in combination with any rinse was more effective than toothbrushing alone. No statistically significant differences were found between the alcohol-free and the alcohol-containing control rinses.

Formulation of unidirectional release buccal patches of carbamazepine and study of permeation through porcine buccal mucosa

OBJECTIVE

To achieve transbuccal release of carbamazepine by loading in unidirectional release mucoadhesive buccal patches.

METHODS

Buccal patches of carbamazepine with unidirectional drug release were prepared using hydroxypropyl methyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone and ethyl cellulose by solvent casting method. Water impermeable backing layer (Pidilite® Biaxially-oriented polypropylene film) of patches provided unidirectional drug release. They were evaluated for thickness, mass uniformity, surface pH and folding endurance. Six formulations FA2, FA8, FA10, FB1, FB14 and FB16 (folding endurance above 250) were evaluated further for swelling studies, ex vivo mucoadhesive strength, ex vivo mucoadhesion time, In vitro drug release, ex vivo permeation, accelerated stability studies and FTIR and XRD spectral studies.

RESULTS

The ex vivo mucoadhesion time of patches ranged between 109 min (FA10) to 126 min (FB14). The ex vivo mucoadhesive force was in the range of 0.278 to 0.479 kg/m/s. The In vitro drug release studies revealed that formulation FA8 released 84% and FB16 released 99.01% of drug in 140 min.

CONCLUSIONS

The prepared unidirectional buccal patches of carbamazepine provided a maximum drug release within specified mucoadhesion period and it indicates a potential alternative drug delivery system for systemic delivery of carbamazepine.

Novel antioxidants are not toxic to normal tissues but effectively kill cancer cells

Free radicals are formed as a result of cellular processes and play a key role in predisposition to and development of numerous diseases and of premature aging. Recently, we reported the syntheses of a number of novel phenolic antioxidants for possible application in food industry. In the present study, analyses of the cellular processes and molecular gene expression effects of some of the novel antioxidants in normal human tissues and in cancer cells were undertaken. Results indicated that whereas the examined antioxidants showed no effects on morphology and gene expression of normal human oral and gingival epithelial tissues, they exerted a profound cell killing effect on breast cancer cells, including on chemotherapy-resistant breast cancer cells and on oral squamous carcinoma cells. Among the tested antioxidants, N-decyl-N-(3-methoxy-4-hydroxybenzyl)-3-(3,4-dihydroxyphenyl) propanamide and N-decyl-N-(3,5-dimethoxy-4-hydroxybenzyl)-3-(3,4-dihydroxyphenyl) propanamide were the most promising, with excellent potential for cancer treatment. Moreover, our gene expression databases can be used as a roadmap for future analysis of mechanisms of antioxidant action.

The use of ethanol in paediatric formulations in New Zealand

Children's right to access safe and effective medicines is recognised globally. Ethanol, used in paediatric liquid formulations as a solvent and preservative, is associated with safety concerns with respect to both acute ingestion and chronic exposure. In addition, families may have cultural or religious values making ethanol use inappropriate when alternatives are available. International guidelines aim to reduce, and if possible eliminate, the use of ethanol in paediatric medicines. Guidelines on labelling vary globally, limiting the ability of health professionals and patients to make informed decisions on appropriate medicines. This study aimed to explore the availability of ethanol-containing medicines for use in the paediatric population in New Zealand and to discuss findings alongside international guidelines. Forty-seven paediatric liquid medicines were identified containing ethanol. The ethanol concentration could be determined in 35 of these medicines and ranged from 0.6 % v/v to an alarming 76 % v/v ethanol. If recommended dosing instructions are followed, the ethanol consumed per dose is not expected to cause acute toxic effects. The medicines identified are indicated for both acute and chronic use, including digoxin (10.1-11.4 % v/v ethanol) which is used in patients of all ages, including preterm neonates.

CONCLUSION

Stronger guidance should be provided to reduce the use of ethanol in paediatric medicines, in New Zealand and globally. If ethanol is used, full disclosure of its presence and concentration on the product label is essential to enable prescribers and patients to make informed decisions on the most suitable pharmaceutical formulations.

Cytological changes in the oral mucosa after use of a mouth rinse with alcohol. A prospective double blind control study

AIM

The aim of this preliminary study was to detect cytological changes in the oral mucosa after using a mouth wash with alcohol.

MATERIAL AND METHODS

A prospective double-blind, controlled study was performed, for 6 months. Group 1 consisted of 30 subjects who used a mouth rinse with 26.9% of alcohol [Listerine] and Group 2 consisted of 30 subjects who used a mouth rinse with the same ingredients but with no alcohol. We obtained three cytological samples from the oral mucosa. The presence of cytological atypia, binucleation and karyorrhesis, and type of cells were studied. We also used a fluorescent in situ hybridization technique (FISH) in 15 samples in each group, for the micronucleus.

RESULTS

We found no clinical mucosal alteration after using the mouth wash at the end of the study in either group. We observed no cytological differences between the groups at the end of the study (p>0.05). Regarding the study of the micronucleus by FISH, we observed no significant difference between the groups (p>0.05).

CONCLUSIONS

Our results showed no cytological alteration in patients using a mouth rinse with alcohol, but these findings should be considered preliminary results, to be confirmed in a greater sample of patients.

Effectiveness and safety of a mouthwash containing essential oil ingredients

The mouthwash, Listerine®, was compounded in 1879 from four essential oils. Later, the oils were replaced by one ingredient per oil with approximately 25% ethanol as a vehicle to keep them in solution. From then on, Listerine® was no longer a medicinal plant product. In 2003, a review by the FDA Subcommittee on Oral Health Care Drug Products for Over-the-Counter Human Use concluded that the product is effective and safe, and a review of studies published in the meantime showed that Listerine® fulfils the consensus criteria for an effective antigingivitis/antiplaque product. However, concerns have been raised about the long-term safety of some of the ingredients, particularly the ethanol content, and in the light of these concerns, the evidence has been re-examined for both the efficacy and safety of Listerine®. In summary, the studies support the claim that Listerine® shows benefit for oral health, but the concerns over its safety remain to be clarified. Until these have been addressed, high risk populations (children, alcohol addicts, patients with genetic deficiencies in ethanol metabolism) should use alcohol-free mouthwashes for the maintenance of oral health.

Tissue-engineered oral mucosa

Advances in tissue engineering have permitted the three-dimensional (3D) reconstruction of human oral mucosa for various in vivo and in vitro applications. Tissue-engineered oral mucosa have been further optimized in recent years for clinical applications as a suitable graft material for intra-oral and extra-oral repair and treatment of soft-tissue defects. Novel 3D in vitro models of oral diseases such as cancer, Candida, and bacterial invasion have been developed as alternatives to animal models for investigation of disease phenomena, their progression, and treatment, including evaluation of drug delivery systems. The introduction of 3D oral mucosal reconstructs has had a significant impact on the approaches to biocompatibility evaluation of dental materials and oral healthcare products as well as the study of implant-soft tissue interfaces. This review article discusses the recent advances in tissue engineering and applications of tissue-engineered human oral mucosa.