Acute and substantive action of antimicrobial toothpastes and mouthrinses on oral biofilm in vitro

Pilot randomized trial of the effect of antibacterial mouthwash on muscle contractile function in healthy young adults

Antiseptic mouthwash use is widespread due to its oral health benefits. However, its impact on systemic physiological processes, particularly nitric oxide (NO) bioavailability and muscle contractility, is not fully understood. We sought to determine the effects of cetylpyridinium (antibacterial) versus sodium chloride (control) mouthwashes on salivary and breath NO markers and muscle contractile function in healthy young adults. Thirty participants (n = 15/group) completed a randomized, parallel-arm, blinded trial, comparing the two mouthwashes before and after 7 d of treatment. NO bioavailability was inferred via measurement of salivary nitrate (NO3-), nitrite (NO2-), and cyclic guanyl monophosphate (cGMP) concentrations and breath NO level. Contractile function of the knee extensor muscles was determined via isokinetic dynamometry. No changes in salivary NO3-, NO2-, or cGMP or in breath NO were observed in response to either treatment. However, cetylpyridinium mouthwash reduced the percentage of NO2- in saliva (17 ± 10% vs. 25 ± 13%; p = 0.0036). Peak torque at velocities of 0-6.28 rad/s was unaffected by mouthwash use. Calculated maximal knee extensor velocity (Vmax) and power (Pmax) were therefore also unchanged. Cetylpyridinium mouthwash reduces the relative abundance of NO2- in the oral cavity but does not significantly diminish overall NO bioavailability or impair muscle contractile function in healthy young adults.

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 a Stannous Fluoride Dentifrice on Biofilm Composition, Gene Expression and Biomechanical Properties

An in situ study was conducted to examine the mode of action of a 0.454% stannous fluoride (SnF₂)-containing dentifrice in controlling the composition and properties of oral biofilm. Thirteen generally healthy individuals participated in the study. Each participant wore an intra-oral appliance over a 48-h period to measure differences in the resulting biofilm’s architecture, mechanical properties, and bacterial composition after using two different toothpaste products. In addition, metatranscriptomics analysis of supragingival plaque was conducted to identify the gene pathways influenced. The thickness and volume of the microcolonies formed when brushing with the SnF₂ dentifrice were dramatically reduced compared to the control 0.76% sodium monofluorophosphate (MFP)-containing toothpaste. Similarly, the biophysical and nanomechanical properties measured by atomic force microscopy (AFM) demonstrated a significant reduction in biofilm adhesive properties. Metatranscriptomic analysis identified pathways associated with biofilm formation, cell adhesion, quorum sensing, and N-glycosylation that are significantly downregulated with SnF₂. This study provides a clinically relevant snapshot of how the use of a stabilized, SnF₂ toothpaste formulation can change the spatial organization, nanomechanical, and gene expression properties of bacterial communities.

Microbial approaches for the assessment of toothpaste efficacy against oral species: A method comparison

Antibacterial properties of toothpastes enable chemical plaque control in limited‐access tooth regions that are mechanically not sufficiently reached by toothbrushes. Therefore, this study aimed to compare different microbial methods to assess antimicrobial toothpaste properties and evaluate different toothpastes in terms of their antibacterial efficacy against different oral microorganisms in an in vitro setting. Six toothpaste suspensions with varying antibacterial supplements were applied to a multispecies biofilm model (Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, and Streptococcus mutans) as well as to each microorganism. A culture method was used to assess the anti‐biofilm effects and two different agar diffusion assays were performed for testing the antimicrobial effect on each microorganism. The measurements of the culture and diffusion analyses were statistically normalized and compared and toothpastes were ranked according to their antimicrobial efficacy. The results of both agar diffusion assays showed a high correlation across all tested species (Spearman correlation coefficients ρ_s > 0.95). The results of the multispecies biofilm model, however, substantially differed in its assessment of antibacterial properties (ρ_s ranging from 0.22 to 0.87) compared to the results of both diffusion assays. Toothpastes with amine fluoride (with and without stannous fluoride), and toothpastes with triclosan resulted in the highest antimicrobial efficacy. Activated carbon supplements in toothpastes were comparable in their antimicrobial action to the negative control NaCl. The appropriate selection of a broad range of oral microorganisms seems crucial when testing the chemical impact of toothpaste and toothpaste supplements.

The inhibitory effects of toothpaste and mouthwash ingredients on the interaction between the SARS-CoV-2 spike protein and ACE2, and the protease activity of TMPRSS2 in vitro

SARS-CoV-2 enters host cells when the viral spike protein is cleaved by transmembrane protease serine 2 (TMPRSS2) after binding to the host angiotensin-converting enzyme 2 (ACE2). Since ACE2 and TMPRSS2 are expressed in the tongue and gingival mucosa, the oral cavity is a potential entry point for SARS-CoV-2. This study evaluated the inhibitory effects of general ingredients of toothpastes and mouthwashes on the spike protein-ACE2 interaction and the TMPRSS2 protease activity using an in vitro assay. Both assays detected inhibitory effects of sodium tetradecene sulfonate, sodium N-lauroyl-N-methyltaurate, sodium N-lauroylsarcosinate, sodium dodecyl sulfate, and copper gluconate. Molecular docking simulations suggested that these ingredients could bind to inhibitor-binding site of ACE2. Furthermore, tranexamic acid exerted inhibitory effects on TMPRSS2 protease activity. Our findings suggest that these toothpaste and mouthwash ingredients could help prevent SARS-CoV-2 infection.

An assessment of the current status of children's toothpaste in Australia

BACKGROUND

Despite recommendations that pre-school children use toothpaste containing 500-550 ppm of fluoride, there has been an increase in non-fluoridated toothpastes marketed for children. This study investigated children's toothpaste in Australia.

METHODS

A comprehensive audit of all toothpastes marketed for pre-school children and available in store in the Macarthur region of NSW, Australia, was carried out. All toothpastes available for purchase were obtained and examined; size and price were catalogued, along with ingredient lists and fluoride levels.

RESULTS

One hundred and seven individual toothpastes were identified in the audit, with 67 (62.6%) containing no fluoride. Of the 40 fluoridated toothpastes, only 11 (10.3%) contained the recommended level of fluoride of 500-550 ppm. Twenty-two (20.6%) of all toothpastes were made in Australia, all of which were non-fluoridated. Six (5.6%) of the toothpastes studied contained excessive levels of fluoride (1350-1500 ppm). Seventeen of the 20 least expensive toothpastes contained fluoride, while 18 of the 20 most expensive toothpastes were non-fluoridated.

CONCLUSIONS

Despite expert recommendations, the majority of children's toothpaste available in Australia contains either no fluoride or the wrong levels of fluoride. Further study is needed to determine why this change is occurring and what is influencing the increase in non-fluoride toothpastes on the market.

Next-Generation Sequencing for Determining the Effect of Arginine on Human Dental Biofilms Using an In Situ Model

Oral biofilms are associated with caries, periodontal diseases, and systemic diseases. Generally, antimicrobial therapy is used as the first line of treatment for infectious diseases; however, bacteria in biofilms eventually develop antibiotic resistance. This study aimed to apply our in situ biofilm model to verify whether an arginine preparation is useful for plaque control. Ten healthy subjects who did not show signs of caries, gingivitis, or periodontitis were recruited. The dental biofilms from the subjects were obtained using our oral device before and after gargling with arginine solution for 4 weeks. We found that 8% arginine solution significantly increased the concentration of ammonium ions (NH₄ ⁺) in vitro and in vivo in saliva (p < 0.05) and decreased the proportions of the genera Atopobium and Catonella in vivo. However, the viable count was unaffected by the mouthwash. Further, oral populations of the genera Streptococcus and Neisseria tended to increase with the use of arginine. Therefore, we concluded that using an 8% arginine solution decreased the NH₄ ⁺ concentration in the oral cavity without affecting the number of viable bacteria, and that the diversity of oral bacterial flora changed. We suggest that arginine might help prevent mature biofilm formation.

The effectiveness of systematic perioperative oral hygiene in reduction of postoperative respiratory tract infections after elective thoracic surgery in adults: a systematic review

BACKGROUND

Nosocomial infections are a significant contributor to patient morbidity and mortality. Nosocomial infections significantly increase hospital length of stay and total hospital costs. Thoracic surgery, mechanical ventilation and/or admission to an intensive care unit are known to increase patients' risk for nosocomial respiratory tract infection.

OBJECTIVES

To identify, appraise and synthesize the best available evidence on the effectiveness of systematic perioperative oral hygiene in the reduction of postoperative respiratory airway infections in adult patients undergoing elective thoracic surgery.

INCLUSION CRITERIA

Patients over the age of 18 years who had been admitted for elective thoracic surgery, regardless of gender, ethnicity, diagnosis severity, co-morbidity or previous treatment.Perioperative systematic oral hygiene (such as mechanical removal of dental biofilm or plaques and/or systematic use of mouth rinse) performed by patients themselves or by healthcare staff (such as nurses).Randomized controlled trials and quasi-experimental studies.Nosocomial infections, specifically respiratory tracts infections, and surgical site infections

SEARCH STRATEGY

Multiple databases (PubMed, CINAHL, Embase, Scopus, Swemed+, Health Technology Assessment Database and Turning Research Into Practice [TRIP] database) were searched from 1980 to December 2014. Studies published in English, German, Danish, Swedish and Norwegian were considered for inclusion in this review.

METHODOLOGICAL QUALITY

Two independent reviewers used the standard critical appraisal tool from the Joanna Briggs Institute to assess the methodological quality of studies.

DATA EXTRACTION

The process of data extraction was undertaken independently by two reviewers using tools from the Joanna Briggs Institute.

DATA SYNTHESIS

Quantitative results were synthesized in meta-analysis.

RESULTS

This review includes six studies: three randomized controlled trials and three quasi-experimental studies.The absolute magnitude of the summary effect sizes were: for nosocomial infections relative risk (RR) 0.65 (95% confidence interval [CI] 0.55-0.78) for respiratory tract infections RR 0.48 (95%CI: 0.36-0.65) and for deep surgical site infections RR 0.48 (95%CI 0.27-0.84).

CONCLUSIONS

Systematic perioperative oral hygiene reduces postoperative nosocomial, lower respiratory tract infections and surgical site infections but not urinary tract infections. The effect is statistically, clinically and practically significant.Perioperative decontamination of the nasopharynx and/or oropharynx is a strategy worth pursuing. The intervention is cheap and can easily be carried out by the patients themselves. (Grade A)Studies testing decontamination of the nasopharynx and/or oropharynx have until now only included patients undergoing thoracic surgical procedures. As the interventions are cheap, easy to carry out and have a great impact on the patients' outcome, it is recommendable to carry out more studies involving other type of patients undergoing major surgery with a high prevalence of nosocomial infections, respiratory tract infections and surgical site infections.

Nylon Bristles and Elastomers Retain Centigram Levels of Triclosan and Other Chemicals from Toothpastes: Accumulation and Uncontrolled Release

Triclosan (TCS), a broad-spectrum antimicrobial, is used in commercial toothpastes with reported dental benefits. Our studies on 22 popular manual toothbrushes in the U.S. showed that common toothbrush head components can accumulate substantial amounts of TCS after brushing with TCS-formulated toothpastes (TCS-TPs). After simulated 3-month brushing with a commercial best-selling TCS-TP, over one third of the adults' toothbrushes showed a cumulative TCS uptake of 21-37.5 mg, equivalent to 7-12.5 doses of the TCS used per brushing. Similar results were observed on children's toothbrushes with small pea-size heads. Elastomer components were found to be the main contributor while both nylon bristles and elastomers could act as absorptive sinks for TCS during brushing. Studies on six different TCS-TPs containing 0.3 wt% TCS showed similar profiles of TCS accumulation. The absorbed TCS was gradually released into toothpaste slurries after switching to TCS-free alternatives. Release of TCS, which typically measured at a fraction (<75%) of the standard dose using the TCS-TPs, continued for over 2 weeks and occurred most rapidly in peroxide-containing "whitening" toothpastes, followed by alkaline and surfactant-rich toothpastes. The accumulating effect was not exclusive to TCS but was commonly observed on several chemicals identified in TCS-TPs and a range of regular toothpastes.

Sustained-release drug delivery of antimicrobials in controlling of supragingival oral biofilms

INTRODUCTION

Dental caries, a bacterial biofilm-associated disease, is a prevalent oral health problem. It is a bacterial biofilm-associated disease. Conventional means of combating this disease involves oral hygiene, mostly tooth brushing. Supplementary means of prevention and treatment is often necessary. The use of sustained-release delivery systems, locally applied to the oral cavity appears to be one of the most acceptable avenues for the delivery of antimicrobial agents. Area covered: The development and current approaches of local sustained delivery technologies applied to the oral cavity for treatment and prevention of dental caries is discussed. The use of polymeric drug delivery systems, varnishes, liposomes and nanoparticles is presented. Expert opinion: The use of local sustained-release delivery systems applied to the oral cavity has numerous clinical, pharmacological and toxicological advantages over conventional means. Various sustained-release technologies have been suggested over the course of several years. The current research on oral diseases concentrates predominantly on improving the drug delivery. With progress in pharmaceutical technology, sophisticated controlled-release platforms are being developed. The sustained release concept is innovative and there are few products available for the benefit of all populations. Harmonizing academic research with the dental industry will surely expedite the development and commercialization of more products of such pharmacological nature.