Chlorhexidine: is it still the gold standard?

Preprocedural mouth rinses for preventing transmission of infectious diseases through aerosols in dental healthcare providers

BACKGROUND

Aerosols and spatter are generated in a dental clinic during aerosol-generating procedures (AGPs) that use high-speed hand pieces. Dental healthcare providers can be at increased risk of transmission of diseases such as tuberculosis, measles and severe acute respiratory syndrome (SARS) through droplets on mucosae, inhalation of aerosols or through fomites on mucosae, which harbour micro-organisms. There are ways to mitigate and contain spatter and aerosols that may, in turn, reduce any risk of disease transmission. In addition to personal protective equipment (PPE) and aerosol-reducing devices such as high-volume suction, it has been hypothesised that the use of mouth rinse by patients before dental procedures could reduce the microbial load of aerosols that are generated during dental AGPs.

OBJECTIVES

To assess the effects of preprocedural mouth rinses used in dental clinics to minimise incidence of infection in dental healthcare providers and reduce or neutralise contamination in aerosols.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 4 February 2022.

SELECTION CRITERIA

We included randomised controlled trials and excluded laboratory-based studies. Study participants were dental patients undergoing AGPs. Studies compared any preprocedural mouth rinse used to reduce contaminated aerosols versus placebo, no mouth rinse or another mouth rinse. Our primary outcome was incidence of infection of dental healthcare providers and secondary outcomes were reduction in the level of contamination of the dental operatory environment, cost, change in mouth microbiota, adverse events, and acceptability and feasibility of the intervention.

DATA COLLECTION AND ANALYSIS

Two review authors screened search results, extracted data from included studies, assessed the risk of bias in the studies and judged the certainty of the available evidence. We used mean differences (MDs) and 95% confidence intervals (CIs) as the effect estimate for continuous outcomes, and random-effects meta-analysis to combine data  MAIN RESULTS:  We included 17 studies with 830 participants aged 18 to 70 years. We judged three trials at high risk of bias, two at low risk and 12 at unclear risk of bias.  None of the studies measured our primary outcome of the incidence of infection in dental healthcare providers.  The primary outcome in the studies was reduction in the level of bacterial contamination measured in colony-forming units (CFUs) at distances of less than 2 m (intended to capture larger droplets) and 2 m or more (to capture droplet nuclei from aerosols arising from the participant's oral cavity). It is unclear what size of CFU reduction represents a clinically significant amount. There is low- to very low-certainty evidence that chlorhexidine (CHX) may reduce bacterial contamination, as measured by CFUs, compared with no rinsing or rinsing with water. There were similar results when comparing cetylpyridinium chloride (CPC) with no rinsing and when comparing CPC, essential oils/herbal mouthwashes or boric acid with water. There is very low-certainty evidence that tempered mouth rinses may provide a greater reduction in CFUs than cold mouth rinses. There is low-certainty evidence that CHX may reduce CFUs more than essential oils/herbal mouthwashes. The evidence for other head-to-head comparisons was limited and inconsistent.  The studies did not provide any information on costs, change in micro-organisms in the patient's mouth or adverse events such as temporary discolouration, altered taste, allergic reaction or hypersensitivity. The studies did not assess acceptability of the intervention to patients or feasibility of implementation for dentists.  AUTHORS' CONCLUSIONS: None of the included studies measured the incidence of infection among dental healthcare providers. The studies measured only reduction in level of bacterial contamination in aerosols. None of the studies evaluated viral or fungal contamination. We have only low to very low certainty for all findings. We are unable to draw conclusions regarding whether there is a role for preprocedural mouth rinses in reducing infection risk or the possible superiority of one preprocedural rinse over another. Studies are needed that measure the effect of rinses on infectious disease risk among dental healthcare providers and on contaminated aerosols at larger distances with standardised outcome measurement.

Clinical Effectiveness of Herbal Oral Care Products in Periodontitis Patients: A Systematic Review

BACKGROUND

The use of herbal products in oral cavity has shown an increased popularity and potential benefits due to their additional anti-inflammatory and antioxidant properties as well as the lack of side effects related to their use.

OBJECTIVE

To assess the clinical effectiveness of herbal dental products (mouthwash, dentifrice, gel) when compared to conventional products or placebo in periodontitis patients.

MATERIAL AND METHODS

A systematic review with 22 studies was carried out using MEDLINE/Pubmed, EMBASE and Web of Science databases in addition to hand searches. Randomized and non-randomized clinical trials that evaluated the effect of any herbal dental product and compared it with conventional products or placebo in periodontitis patients and published up to March 2022, were screened.

RESULTS

Herbal products used as adjuncts to scaling and root planing (SRP) or supragingival debridement (SPD) led to superior clinical outcomes than placebo or no adjuncts (8 studies). In conjunction with SRP, these products showed comparable outcomes with chlorhexidine (6 studies) or better (4 studies). When used as adjuncts to SPD, herbal oral care products demonstrated comparable outcomes with chlorhexidine and conventional products (4 studies).

CONCLUSIONS

Within the limitations of this systematic review, herbal oral care products may play a key role in the management of periodontal disease. Further well-designed studies are needed to establish their efficacy.

Ecological Effects of Daily Antiseptic Treatment on Microbial Composition of Saliva-Grown Microcosm Biofilms and Selection of Resistant Phenotypes

Antiseptics are widely used in dental practice and included in numerous over-the-counter oral care products. However, the effects of routine antiseptic use on microbial composition of oral biofilms and on the emergence of resistant phenotypes remain unclear. Microcosm biofilms were inoculated from saliva samples of four donors and cultured in the Amsterdam Active Attachment biofilm model for 3 days. Then, they were treated two times daily with chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC) for a period of 7 days. Ecological changes upon these multiple antiseptic treatments were evaluated by semiconductor-based sequencing of bacterial 16S rRNA genes and identification of amplicon sequence variants (ASVs). Furthermore, culture-based approaches were used for colony-forming units (CFU) assay, identification of antiseptic-resistant phenotypes using an agar dilution method, and evaluation of their antibiotic susceptibilities. Both CHX and CPC showed only slight effects on CFU and could not inhibit biofilm growth despite the two times daily treatment for 7 days. Both antiseptics showed significant ecological effects on the microbial compositions of the surviving microbiota, whereby CHX led to enrichment of rather caries-associated saccharolytic taxa and CPC led to enrichment of rather gingivitis-associated proteolytic taxa. Antiseptic-resistant phenotypes were isolated on antiseptic-containing agar plates, which also exhibited phenotypic resistance to various antibiotics. Our results highlight the need for further research into potential detrimental effects of antiseptics on the microbial composition of oral biofilms and on the spread of antimicrobial resistance in the context of their frequent use in oral healthcare.

Evaluation of antimicrobial and cytotoxic effects of Echinacea and Arctium extracts and Zataria essential oil

Dental caries and oral infections have become a widespread issue in the modern world. This study aimed to investigate the antibacterial, antifungal, and cytotoxicity characteristics of the extracts of Echinacea purpura, Arctium lappa, and the essential oil of Zataria multiflora as a potential herbal mouthwash. The essential oil of Z. multiflora leaves and the extracts of E. purpurea and A. lappa roots were prepared. The characterization was carried out by GC-MS and also, total phenol and flavonoid were assed for all three samples. The antimicrobial and anti-biofilm effects were evaluated against Streptococcus mutans, Streptococcus mitis, Streptococcus salivarius, Lactobacillus acidophilus, Escherichia coli, Staphylococcus aureus, and Candida albicans. The cytotoxic effect of the samples was evaluated on HEK 293 and HDFa cells by MTT test. Thymol and carvacrol contents in EO of Z. multiflora were measured at 31% and 42.2%, respectively. A. lappa had the lowest total phenolic and flavonoid value among the samples. On the other hand, the total phenolic content of Z. multiflora and the total flavonoid content of E. purpurea were the highest. The MIC values of Zataria, Arctium, and Echinacea against S. mutans were 0.011% v/v, 187.5 mg/ml, and 93.75 mg/ml, while MBC were 0.011% v/v, 375 mg/ml, and 187.5 mg/ml, respectively. The formulation showed bactericidal activity against S. mutans in the concentration of 5.86 mg/ml for Echinacea and Burdock extracts and 0.08 µl/ml for EO of Zataria. The formulation significantly affected microbial biofilm formation and induced biofilm degradation. The cell viability percentages were higher than 50% during 24 and 48 h. The formulation had a significant antimicrobial effect on cariogenic bacteria and C. albicans, with the lowest cytotoxic effects. Therefore, this formulation can be an appropriate candidate for mouthwash.

Aloe vera mouthwashes can be a natural alternative to chemically formulated ones - A randomized-controlled trial

Objectives

To evaluate the antiplaque and antibacterial efficacy of commercially available mouthwashes containing aloe vera (AV), hydrogen peroxide (HP), and cetylpyridinium chloride (CPC) in a 4-day plaque regrowth study.

Methods

Plaque score and salivary samples were assessed (Day-0 and Day-4) in 96 participants in a randomised, double-blind prospective parallel-arm 4-day plaque regrowth study. Participants were divided into five groups who refrained from engaging in regular oral hygiene measures during the study period and used commercially available mouthwashes containing AV, HP, and CPC as test products with distilled water (DW) and chlorhexidine (CHX) mouthwash as negative and positive controls, respectively. Salivary bacterial count was expressed as colony-forming units (CFU) (culture method).

Results

There was a significant difference both in plaque score (p < 0.001) and in CFU (p < 0.001) among the study mouthwashes at Day-4. The plaque score and CFU of AV were significantly higher and lower than those of CHX and DW, respectively. The plaque score of HP was significantly higher than that of AV (p = 0.016) and CPC (p < 0.001). No significant difference was observed between AV and CPC (p = 0.70). Moreover, the CFU of HP was significantly higher than that of CPC (p = 0.04). There was no statistically significant difference between the CFU of mouthwashes containing AV and HP (p = 0.912) or AV and CPC (p = 0.280). No significant difference was seen in the inhibition of plaque and salivary bacterial count between AV, HP, and CPC.

Conclusion

The antiplaque and antibacterial efficacy of commercially available AV mouthwash was similar to that of CPC and significantly better than that of HP mouthwash and can be a natural alternative to chemically formulated mouthwashes.

Evidence on the Use of Mouthwash for the Control of Supragingival Biofilm and Its Potential Adverse Effects

Antimicrobial mouthwash improves supragingival biofilm control when used in conjunction with mechanical removal as part of an oral hygiene routine. Mouthwash is intended to suppress bacterial adhesion during biofilm formation processes and is not aimed at mature biofilms. The most common evidence-based effects of mouthwash on the subgingival biofilm include the inhibition of biofilm accumulation and its anti-gingivitis property, followed by its cariostatic activities. There has been no significant change in the strength of the evidence over the last decade. A strategy for biofilm control that relies on the elimination of bacteria may cause a variety of side effects. The exposure of mature oral biofilms to mouthwash is associated with several possible adverse reactions, such as the emergence of resistant strains, the effects of the residual structure, enhanced pathogenicity following retarded penetration, and ecological changes to the microbiota. These concerns require further elucidation. This review aims to reconfirm the intended effects of mouthwash on oral biofilm control by summarizing systematic reviews from the last decade and to discuss the limitations of mouthwash and potential adverse reactions to its use. In the future, the strategy for oral biofilm control may shift to reducing the biofilm by detaching it or modulating its quality, rather than eliminating it, to preserve the benefits of the normal resident oral microflora.

Hydroxyapatite as Remineralization Agent for Children's Dental Care

Children are prone to develop dental caries. This is supported by epidemiological data confirming early childhood caries (ECC) as a highly prevalent disease affecting more than every second child worldwide. ECC is known to result from an imbalance between re- and demineralization where demineralization dominates due to frequent acid production by cariogenic bacteria present in oral biofilms. The application of oral care formulations containing remineralizing agents helps to prevent dental caries. As young children are sensitive and usually swallow (intended or unintended) a majority of toothpaste or other oral care products during daily dental care, all ingredients, especially the actives, should be non-toxic. Biomimetic hydroxyapatite [HAP; Ca5(PO4)3(OH)] is known to have favorable remineralizing properties combined with an excellent biocompatibility, i.e., it is safe if accidently swallowed. Several clinical trials as well as in situ and in vitro studies have shown that HAP remineralizes enamel and dentin. Remineralization occurs due to deposition of HAP particles on tooth surfaces forming mineral-mineral bridges with enamel crystals, but also indirectly through calcium and phosphate ions release as well as HAP's buffering properties in acidic environments (i.e., in plaque). HAP induces a homogenous remineralization throughout the subsurface enamel lesions. This review summarizes the current evidence showing HAP as an effective remineralizing agent in oral care products for children. Additional studies showing also further beneficial effects of HAP such as the reduction of biofilm formation and the relief of hypersensitivity in children with molar incisor hypomineralization (MIH). It can be concluded that HAP is an effective and safe remineralizing agent for child dental care.

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

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

Transcriptomic Stress Response in Streptococcus mutans following Treatment with a Sublethal Concentration of Chlorhexidine Digluconate

Despite the widespread use of antiseptics such as chlorhexidine digluconate (CHX) in dental practice and oral care, the risks of potential resistance toward these antimicrobial compounds in oral bacteria have only been highlighted very recently. Since the molecular mechanisms behind antiseptic resistance or adaptation are not entirely clear and the bacterial stress response has not been investigated systematically so far, the aim of the present study was to investigate the transcriptomic stress response in Streptococcus mutans after treatment with CHX using RNA sequencing (RNA-seq). Planktonic cultures of stationary-phase S. mutans were treated with a sublethal dose of CHX (125 µg/mL) for 5 min. After treatment, RNA was extracted, and RNA-seq was performed on an Illumina NextSeq 500. Differentially expressed genes were analyzed and validated by qRT-PCR. Analysis of differential gene expression following pathway analysis revealed a considerable number of genes and pathways significantly up- or downregulated in S. mutans after sublethal treatment with CHX. In summary, the expression of 404 genes was upregulated, and that of 271 genes was downregulated after sublethal CHX treatment. Analysis of differentially expressed genes and significantly regulated pathways showed regulation of genes involved in purine nucleotide synthesis, biofilm formation, transport systems and stress responses. In conclusion, the results show a transcriptomic stress response in S. mutans upon exposure to CHX and offer insight into potential mechanisms that may result in development of resistances.

The Application of Small Molecules to the Control of Typical Species Associated With Oral Infectious Diseases

Oral microbial dysbiosis is the major causative factor for common oral infectious diseases including dental caries and periodontal diseases. Interventions that can lessen the microbial virulence and reconstitute microbial ecology have drawn increasing attention in the development of novel therapeutics for oral diseases. Antimicrobial small molecules are a series of natural or synthetic bioactive compounds that have shown inhibitory effect on oral microbiota associated with oral infectious diseases. Novel small molecules, which can either selectively inhibit keystone microbes that drive dysbiosis of oral microbiota or inhibit the key virulence of the microbial community without necessarily killing the microbes, are promising for the ecological management of oral diseases. Here we discussed the research progress in the development of antimicrobial small molecules and delivery systems, with a particular focus on their antimicrobial activity against typical species associated with oral infectious diseases and the underlying mechanisms.

Effect of pH-sensitive nanoparticles on inhibiting oral biofilms

Dental caries is a biofilm-related preventable infectious disease caused by interactions between the oral bacteria and the host’s dietary sugars. As the microenvironments in cariogenic biofilms are often acidic, pH-sensitive drug delivery systems have become innovative materials for dental caries prevention in recent years. In the present study, poly(DMAEMA-co-HEMA) was used as a pH-sensitive carrier to synthesize a chlorhexidine (CHX)-loaded nanomaterial (p(DH)@CHX). In vitro, p(DH)@CHX exhibited good pH sensitivity and a sustained and high CHX release rate in the acidic environment. It also exhibited lower cytotoxicity against human oral keratinocytes (HOKs) compared to free CHX. Besides, compared with free CHX, p(DH)@CHX showed the same antibacterial effects on S. mutans biofilms. In addition, it had no effect on eradicating healthy saliva-derived biofilm, while free CHX exhibited an inhibitory effect. Furthermore, the 16s rDNA sequencing results showed that p(DH)@CHX had the potential to alter oral microbiota composition and possibly reduce caries risk. In conclusion, the present study presents an alternative option to design an intelligent material to prevent and treat dental caries.

Cleaning and Disinfection Protocols for Clear Orthodontic Aligners: A Systematic Review

(1) Background: Clear orthodontic aligners support the development of oral biofilms, which could lead to interferences with the oral microbiota already existing and the deterioration of oral health, with the development of dental caries, periodontal disease and even systemic infections. Therefore, preventive oral health care requires a cleaning and disinfection procedure for aligners. (2) Methods: A systematic review of the literature was conducted across four databases following the PRISMA guidelines up to May 2021, combining an electronic and a manual search. Prospective studies, including randomized controlled trials (RCTs), crossover studies (COSs) and controlled clinical trials (CCTs), published in the English language without time restrictions, evaluating the efficacy of cleaning and disinfection protocols for clear orthodontic aligners by comparing them with a placebo or a negative control, were included. The article selection, data extraction and risk of bias assessment were performed by two independent blinded review authors. In case of disagreement, a third author was solicited throughout the selection process. (3) Results: Among the 221 articles screened in the search process, 4 studies were included in the review, all designed as crossover studies (single arm without randomization with the same sequence of different cleaning and disinfection protocols for each participant). Different cleaning and disinfection methods were studied such as mechanical methods (brushing with toothpaste or vibration), chemical methods/pharmaceutical products (chlorhexidine antibacterial substance, anionic or cationic detergents or effervescent tablets) or combinations of both. (4) Conclusion: Although the determination of the most remarkable method of cleaning and disinfection was impossible because no direct comparison was conducted between all these methods, a multi-step protocol, including the combination of a mechanical and a chemical method, seems to be the most effective approach. Further research is needed to define the most preventive oral health care protocol. Registration: PROSPERO CRD 42021278498.

Efficacy of Probiotic, Chlorhexidine, and Sodium Fluoride Mouthrinses on Mutans Streptococci in 8- to 12-Year-Old Children: A Crossover Randomized Trial

INTRODUCTION

The oral cavity is home to a diverse and distinct microbiome. While the role of oral bacteria in cariogenic and other dental diseases is irrefutable, their beneficial effects in the form of probiotics (PB) has been less studied, especially pertaining to oral diseases in children. This study compares the efficacy of a PB mouthrinse with 0.12% chlorhexidine (CHX) and 0.05% sodium fluoride (NaF) mouthrinse on the colony counts of mutans streptococci (MS) in children.

METHODS

A triple-blind crossover randomized trial between interventional groups was planned. Fifty-one children between 8 to 12 years of age were divided into three groups (I, II, and III) and were exposed to all three mouthrinses (A, B, and C) by randomized allocation for a period of two weeks with an inter-phase washout period of four weeks. Pre- and post-interventional MS counts (CFU/mL) were assessed, and the mean change was analysed using the t test (intragroup) and ANOVA (intergroup and crossover).

RESULTS

The mean changes in the colony counts obtained with the use of PB, CHX, and NaF mouthrinses were -1.0223 (-1.2201 to -0.8246), -0.9564 (-1.1503 to -0.7626), and -0.9511 (-1.1554 to -0.7467), respectively, which were statistically significant (p < 0.0001). However, the intergroup comparison for the mean change in colony counts revealed no statistically significant differences (p > 0.05).

CONCLUSION

The study concluded that the PB mouthrinse was equally efficacious as compared to CHX and NaF mouthrinses against MS in 8- to 12-year-old children. However, further studies are recommended to strengthen the evidence.

Effectiveness of mouthwash against viruses: 2020 perspective. A systematic review

INTRODUCTION

Antiseptic mouthwash is widely recommended to treat various oral diseases as well as to improve oral health. Most of the dental procedures lead to the generation of aerosols. These aerosols have a high potential to transmit disease. Preprocedural oral rinse with antimicrobial agents in the form of mouthwashes reduces the bacterial and viral load many folds. The purpose of this review was to summarize the effectiveness of mouthwash against viruses affecting human beings.

EVIDENCE ACQUISITION

Search engines like PubMed, Google Scholar, and others were used to search the electronic database. Articles were identified in which the effectiveness of antiseptic mouth rinse against the virus was tested. A comprehensive search strategy was designed to select the articles and then independently screened for eligibility.

EVIDENCE SYNTHESIS

A total of 9624 articles out of the 13 titles met the eligibility criteria. The selected papers were included in the present manuscript according to their relevance to the topic. Authors searched the most used chemicals as mouthwashes but records of three types of mouthwash tested against various types of viruses i.e. chlorhexidine gluconate, Povidone-iodine and essential oil containing mouthwash (Listerine) were found.

CONCLUSIONS

Povidone-iodine mouth rinse is effective in reducing viral load either in-vitro or in-vivo conditions. Chlorhexidine gluconate mouthwash and essential oils have shown its effectiveness in a few studies. Insufficient evidence is available to support the claim that oral antiseptics can reduce the risk of developing viral loads in humans or the rate of progression of diseases caused by viruses.

Graphene Oxide-Copper Nanocomposites Suppress Cariogenic Streptococcus mutans Biofilm Formation

Introduction

Dental caries is a biofilm-dependent disease that largely relies on the ability of Streptococcus mutans to synthesize exopolysaccharide matrix. Graphene oxide-based metal nanomaterials, as the derivatives of graphene, are potent agents against pathogens by their impressive antibacterial and anti-biofilm biofunctions. Previously, we fabricated the novel graphene oxide-copper nanocomposites (GO-Cu), maintaining a long-term release of copper nanoparticles. Here, the biofunctionalization of GO-Cu nanocomposites against cariogenic S. mutans is investigated.

Methods

Growth curve observation and colony forming units counting were applied to detect the antibacterial effect of GO-Cu nanocomposites on S. mutans. Scanning electron microscopy and the crystal violet assay were used to detect nanocomposite effects on biofilm forming ability. The production and distribution of exopolysaccharides within biofilm was analyzed and the expression of genes required for biofilm formation was explored. Moreover, the regulatory landscape of GO-Cu nanocomposites on S. mutans pathogenicity was probed.

Results

It has been found that GO-Gu nanocomposites were antibacterial to S. mutans and 10 μg/mL GO-Cu nanocomposites could inhibit the bacteria bioactivity instead of killing them. The biomass of S. mutans biofilm was significantly reduced when treated with 10 μg/mL GO-Cu nanocomposites. Also, 10 μg/mL GO-Cu nanocomposites could alter the biofilm architecture and impair exopolysaccharides production and distribution, and dysregulated the expression of exopolysaccharide-associated genes.

Conclusion

In all, we found low-dose GO-Cu nanocomposites could disrupt exopolysaccharide matrix assembly and further impair optimal biofilm development with minimal cytotoxicity. Therefore, GO-Cu nanocomposites can open up a new avenue for the development of alternative anti-caries biomaterials.

A lingering mouthwash with sustained antibiotic release and biofilm eradication for periodontitis

Dental plaque biofilms are believed to be one of the principal virulence factors in periodontitis resulting in tooth loss. Traditional mouthwashes are limited due to the continuous flow of saliva and poor drug penetration ability in the biofilm. Herein, we fabricated an antibiotic delivery platform based on natural polysaccharides (chitosan and cyclodextrin) as a novel mouthwash for the topical cavity delivery of minocycline. The penetration and residence mechanisms demonstrate that the platform can prolong the residence time up to 12 h on biofilms. Furthermore, sustained release can enhance the penetration of drugs into biofilms. In vitro antibiofilm experimental results indicated that the mouthwash effectively kills bacteria and eradicate biofilms. Effective treatment in vivo was confirmed by the significantly reduced dental plaque and alleviated inflammation observed in a rat periodontitis model. In summary, this novel platform can improve antibiofilm efficiency and prevent drugs from being washed away by saliva, which may provide benefits for many oral infectious diseases.

Virucidal efficacy of chlorhexidine: a systematic review

This study aimed to systematically review the literature about the virucidal efficacy of CHX in comparison to other substances used in the oral cavity. Electronic searches were performed in four databases (PubMed, Scopus, Embase, and Web of Science). Only studies that presented the following characteristics were included: (1) verified virucidal efficacy of CHX against Herpes Simplex Type-1 (HSV-1), any Influenza, or any human coronavirus (HcoV); and (2) compared the virucidal efficacy of CHX with essential oils (Listerine^®), quaternary ammonium compounds, povidone-iodine, hydrogen peroxide, negative control substance, and absence of therapy. Two researchers independently selected the studies, extracted data and evaluated the risk of bias. A narrative data synthesis was used. Twenty-five studies were included, of which 21 were in vitro and four were randomized clinical trials (RCT). Studies assessed the virucidal efficacy of CHX against Herpes Simplex Type-1 (HSV-1) (10 studies), Influenza A (InfluA) (4 studies), human coronavirus (HCoV) (4 studies) and Severe Acute Respiratory Syndrome-Related Coronavirus (SARS-CoV-2) (11 studies). Most studies demonstrated that CHX has a positive virucidal efficacy against HSV-1 and InfluA strains. However, lower efficacy was shown to InfluA strain in comparison to povidone-iodine. Lower to none virucidal efficacy of CHX is expected for HCoV and SARS-CoV-2 strains for in vitro studies. Three RCT demonstrated that CHX was able to significantly reduce the viral load of SARS-CoV-2 for a short period. CHX may present an interesting virucidal efficacy against HSV-1 and InfluA viruses. CHX also presents transient efficacy against SARS-CoV-2 when used as a mouthwash.

Effect of Chlorhexidine Digluconate in Early Wound Healing of Human Gingival Tissues. A Histological, Immunohistochemical and Biomolecular Analysis

Chlorhexidine digluconate (CHX) is considered the gold standard for oral cavity antiseptic treatment. Nevertheless, several in vitro studies have reported detrimental effects in oral tissue repair. The aim of the present study was to evaluate the in vivo effect of post-surgical CHX mouth rinse on gingival tissue (G) 24 h after injury. G biopsies were obtained in three patients 24 h after surgery with the indication of post-surgical 0.12% CHX use and were compared with those obtained from the same patients without any antiseptic use. Changes in collagen production, cell proliferation, and apoptosis were examined by histological and Ki-67/P53 immunohistochemical analysis. Fibrotic markers (COL1A1, αSMA), proapoptotic protein (BAX) expression, and wound healing-related gene modulation (RAC1, SERPINE1, TIMP1) were analyzed by quantitative real-time PCR analysis. CHX was able to reduce cellular proliferation and increase collagen deposition, proapoptotic molecule and fibrotic marker expression, and myofibroblast differentiation, reduce expression of RAC1 and trigger expression of SERPINE1 and TIMP1, showing “scar wound healing response” pattern. This study assessed for the first time the in vivo effects of CHX on gingival tissue. The demonstration of a CHX-induced fibrotic transformation, leading to scar repair, supports the need for new post-surgical clinical protocols based on a strategic and personalized use of CHX.

Nanogels: A novel approach in antimicrobial delivery systems and antimicrobial coatings

The implementation of nanotechnology to develop efficient antimicrobial systems has a significant impact on the prospects of the biomedical field. Nanogels are soft polymeric particles with an internally cross-linked structure, which behave as hydrogels and can be reversibly hydrated/dehydrated (swollen/shrunken) by the dispersing solvent and external stimuli. Their excellent properties, such as biocompatibility, colloidal stability, high water content, desirable mechanical properties, tunable chemical functionalities, and interior gel-like network for the incorporation of biomolecules, make them fascinating in the field of biological/biomedical applications. In this review, various approaches will be discussed and compared to the newly developed nanogel technology in terms of efficiency and applicability for determining their potential role in combating infections in the biomedical area including implant-associated infections.

The Antimicrobial Effect of Pomegranate Peel Extract versus Chlorhexidine in High Caries Risk Individuals Using Quantitative Real-Time Polymerase Chain Reaction: A Randomized Triple-Blind Controlled Clinical Trial

The aim of the present study was to compare the antibacterial effectiveness of chlorhexidine and PPE oral rinse on S. mutans, Lactobacilli, and Veillonella, in clinical salivary samples of patients with advanced stages of dental caries at baseline and two and four weeks with PCR technique. This triple-blind randomized clinical trial involved 60 high caries risk adult patients, 19–59 years of age, randomly allocated into two groups of 30 subjects each. The intervention group received pomegranate peel extract mouthwash, whereas the control group received chlorhexidine mouthwash. Unstimulated pooled saliva was collected from the floor of the mouth before and after the intervention. The quantitative real-time polymerase chain reaction was employed to analyze the bacterial copies of each salivary sample at baseline and two and four weeks. The significance level was fixed at 5% (α = 0.05). Overall comparison of antimicrobial effectiveness across both groups revealed insignificant outcomes. The control group evinced a significant reduction in S. mutans between a specific time, i.e., baseline and 4 weeks (p=0.043). PPE oral rinse as a natural product or ecological alternative was effective in disrupting activity across all microorganisms tested in this triple-blind RCT; however, the nutraceutical, when compared to chlorhexidine, was not as effective against S. mutans.

Efficacy of Xanthan-Based Chlorhexidine Gel on the Levels of Interleukin-1β in Chronic Periodontitis: An Interventional Study

Aims and Objectives:

Xanthan-based chlorhexidine gel (Chlosite®) is a local drug delivery system that exposes the sub-gingival bacteria to the effects of chlorhexidine (CHX) for a prolonged time. Hence, the study aimed at evaluating the clinical efficacy of the subgingival application of Chlosite gel as an adjunctive to mechanical scaling and root planing (SRP) and at evaluating the salivary interleukin (IL)-1β level to substantiate the clinical efficacy of xanthan-based CHX gel.

Materials and Methods:

A total number of 40 patients with chronic periodontitis in the age group of 30–50 years were enrolled in this interventional study. The patients were assigned to group A, in which only SRP was done, and group B, in which SRP along with the subgingival application of Chlosite gel was done. Periodontal parameters and salivary IL-1β level were evaluated, and the data obtained were statistically analyzed by using paired and unpaired “t” tests.

Results:

The results obtained showed a statistically significant reduction in the mean gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL), and salivary IL-1β values in both the groups from baseline to 30 days. There was a statistically significant reduction in GI, in group B when compared with group A, after the treatment. Salivary IL-1β value in group B was slightly lower when compared with group A after the treatment, but it was not statistically significant.

Conclusions:

The xanthan-based CHX gel is therapeutically effective when used as an adjunct to SRP. The study also indicated that salivary IL-1β can be used as a reliable biomarker.

Topical treatment of periodontitis using an iongel

Almost 50 % of the U.S. population suffers from oral infections such as periodontitis. Current treatment options for periodontitis include mechanical cleaning procedures, which are performed often under local anesthesia and are time-consuming. Alternate option includes systemic antibiotics which increase the risk of antimicrobial resistance and are not recommended for prolonged usage. Topical treatments of gingiva-based antimicrobial agents have shown limited efficacy due to poor penetration of the therapeutic into deep gingiva where the infection resides. Herein, we report an Iongel of a Deep Eutectic Antimicrobial (IDEA), which simultaneously exhibits deep tissue penetration and antimicrobial activity against P. gingivalis. In vivo studies confirmed that IDEA successfully penetrated into the gingiva and the gingival sulcus, where the pathogens primarily exist, within a short time. In vitro studies confirmed that the dose delivered was adequate to inactivate P. gingivalis biofilm. In vivo studies in a periodontal rat model confirmed that a topical treatment of IDEA eliminated pathogenic bacteria, and the disease progression was significantly suppressed. Safety studies confirmed excellent tolerance to IDEA. Altogether, IDEA offers a promising topical agent against periodontitis.

Advancements in release-active antimicrobial biomaterials: A journey from release to relief

Escalating medical expenses due to infectious diseases are causing huge socioeconomic pressure on mankind globally. The emergence of antibiotic resistance has further aggravated this problem. Drug-resistant pathogens are also capable of forming thick biofilms on biotic and abiotic surfaces to thrive in a harsh environment. To address these clinical problems, various strategies including antibacterial agent delivering matrices and bactericidal coatings strategies have been developed. In this review, we have discussed various types of polymeric vehicles such as hydrogels, sponges/cryogels, microgels, nanogels, and meshes, which are commonly used to deliver antibiotics, metal nanoparticles, and biocides. Compositions of these polymeric matrices have been elaborately depicted by elucidating their chemical interactions and potential activity have been discussed. On the other hand, various implant/device-surface coating strategies which exploit the release-active mechanism of bacterial killing are discussed in elaboration. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Clinical efficacy of curcumin versus chlorhexidine as an adjunct to scaling and root planing for the treatment of periodontitis: A systematic review and meta-analysis

This study aims to evaluate the clinical efficacy of curcumin versus chlorhexidine as adjuncts to scaling and root planing (SRP) for periodontitis treatment. We searched PubMed, EMbase, Cochrane Library, and ClinicalTrials.gov from inception to February 18, 2021 and identified studies with relevant randomized controlled trials (RCTs) using curcumin or chlorhexidine as an adjunct to SRP. Nine RCTs involving 420 patients/sites were included. A meta-analysis with a random-effects model revealed that curcumin and chlorhexidine, as an adjunct to SRP, reduced probing pocket depth (PPD) at similar levels during a 3-, 4-, 6-, and 12-week follow-up. No significant differences were observed in reducing clinical attachment loss (CAL) between curcumin and chlorhexidine as an adjunct to SRP at 4 weeks and 6 weeks. Furthermore, gingival index (GI) and plaque index (PI) were similar using curcumin versus chlorhexidine as an adjunct to SRP at the 4-week-, 6-week-, and 12-week follow-up. Based on the available evidence in RCTs, compared with chlorhexidine as an adjunct to SRP, curcumin has a similar effect on reducing PPD, CAL, GI, and PI. The quality of evidence is low, limited by the number of studies and their limitations. Further studies are needed to firmly establish the clinical efficacy of curcumin.

Effect of chlorhexidine mouthrinse on prevention of microbial contamination during EBUS-TBNA: a study protocol for a randomized controlled trial

Background

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a standard diagnostic method for mediastinal and hilar lymphadenopathy. Although rare, fatal infectious complications can occur following EBUS-TBNA. However, to date, there is a lack of effective preventive strategies to reduce these complications. We started a trial to investigate the effect of chlorhexidine mouthrinse on the prevention of microbial contamination during EBUS-TBNA.

Methods

This study is a single-center, parallel-group, assessor-blinded randomized controlled trial (RCT). We will enroll 112 adult participants undergoing EBUS-TBNA using a convex probe, and randomly assign them to two groups at a 1:1 ratio. The intervention group will gargle for 1 minute with 100 mL of 0.12% chlorhexidine gluconate before EBUS-TBNA, while the control group will have no mouthrinse before the procedure. Immediately after completion of EBUS-TBNA on all targeted lesions with an aspiration needle, a needle wash sample will be taken by instilling 5 mL of sterile saline into the used needle. The primary outcome is colony forming unit (CFU) counts in aerobic cultures of the needle wash samples. Secondary outcomes are CFU counts in anaerobic cultures, fever within 24 hours after EBUS-TBNA, and infectious complications within 4 weeks after EBUS-TBNA.

Conclusion

This trial was designed as the first RCT to investigate the effect of chlorhexidine mouthrinse on the prevention of microbial contamination during EBUS-TBNA. Results from this trial can provide clinical evidence for a simple, safe, and cost-effective strategy to prevent infectious complications following EBUS-TBNA.

The Effect of Chlorhexidine Disinfectant Gels with Anti-Discoloration Systems on Color and Mechanical Properties of PMMA Resin for Dental Applications

Chlorhexidine (CHX)-based dental hygiene products are widely used by dental patients. As these products may have long-term contact with denture poly(methyl methacrylate) (PMMA) resin, anti-discoloration systems (ADSs) were included in them to prevent discoloration of the natural teeth and dental materials. Purpose: The aim of this study was to evaluate the effect of two newly designed CHX-containing gels with ADSs and two commercial products with ADSs (Curasept 0.5% and Curasept 1%) in preventing staining and to analyze the mechanical properties of heat-curing PMMA denture base resin. Materials and methods: Twenty-five discs (five for each test group) of PMMA dental resin with a thickness of 1 mm and a diameter of 20 mm were polymerized according to the manufacturer’s instructions and stored in distillate water at a temperature of 37 °C. The surface of the specimens was covered with two commercially available gels—Curasept 1% and Curasept 0.5%, or two experimental gel formulations containing 1% CHX. PMMA specimens stored in distilled water were used as control. The initial values of color and Brinell hardness of the specimens were measured immediately after specimen preparation. The changes in color and Brinell hardness, as well as water sorption, and solubility of the specimens were measured after one year of conditioning. Statistical analysis of the obtained data was performed using one-way analysis of variance and Dunn–Bonferroni post hoc tests. Results: In the group of specimens covered with gel 1 with citric acid or Curasept 0.5%, the color change was clinically acceptable (ΔE* < 2.7). In the specimens stored in contact with gel 2 with polyvinylpyrrolidone (PVP) and Curasept 1%, the ΔE* values were 3.6 and 3.67, respectively. In the control group, the level of hardness decreased significantly from 150 to 140 during the experiment. In addition, a statistically significant decrease in hardness was observed in specimens stored with Curasept 1% and gel 2 with PVP. Specimens stored in contact with Curasept 0.5% and gel 1 with citric acid also showed a lower hardness, but the change was not statistically significant. The sorption of all the groups of PMMA specimens ranged from 22.83 to 24.47 µg/mm³, with no significant differences found between them. All the PMMA specimens stored in contact with the tested CHX gels exhibited a significantly higher solubility (6.84 ± 7.91 µg/mm³) compared to the control group (6.74 µg/mm³), with the highest solubility noted for specimens stored with Curasept 1%. Conclusions: The results showed that CHX used in the gel form with ADSs at a concentration of 0.5% and the experimental gel containing 1% CHX with citric acid caused limited changes to the color and mechanical properties of the PMMA denture base resin during the study period. These gels may be safely used by dental patients for oral hygiene regimen even for prolonged periods of time. ADSs contained in these gels seem to be effective in preventing CHX discoloration.

The effect of a toothpaste containing oleanolic acid in reducing plaque and gingivitis: a proof-of-concept randomized trial

OBJECTIVES

To assess the safety and efficacy of an oleanolic acid (OA)-containing toothpaste in reducing gingival inflammation and plaque in patients with gingivitis.

METHODS

This proof-of-concept parallel, double-blind, randomized controlled clinical trial included 99 patients. Following a 1-week washout, patients were randomized into three groups: OA group (fluoride toothpaste containing 0.1% OA and placebo mouthwash); negative control (fluoride toothpaste and placebo mouthwash); and CHX group (fluoride toothpaste and 0.12% chlorhexidine mouthwash). Patients were clinically assessed at inclusion, pre-washout visit, baseline and after 4 days, 1 week and 2 weeks of twice-daily use of the products. Patients received a diary for documentation of bleeding on brushing and provided unstimulated saliva samples.

RESULTS

After two weeks, all groups showed significant reductions in all clinical parameters. The CHX group exhibited significantly greater reductions in gingival index and interproximal gingival index scores at week 2, as compared to patients in the negative control (p = 0.04). In contrast, reductions in gingival index scores did not differ between CHX and OA groups and between OA and negative control groups at week 2. The CHX group had significantly greater reductions in plaque index scores at day-4, 1-week and 2-week evaluations, as compared to the negative control and OA groups. The frequency of adverse events was similar among the groups. None of the groups reduced salivary transferrin levels. Finally, the OA group had the lowest percentage of self-reported bleeding events.

CONCLUSION

OA toothpaste failed to provide antiplaque and antigingivitis effects superior to those of a fluoride toothpaste after 2 weeks of use.

Evaluation of the Efficacy of Lacer HaliTM Treatment on the Management of Halitosis: A Randomized Double-Blind Clinical Trial

Background: Halitosis of oral origin is very common in the general population. Due to their antimicrobial properties, chlorhexidine-based products are widely used in the management of this condition, but these are associated with reversible side effects. In this study we evaluated the efficacy of Lacer Hali^TM mouthrinse and toothpaste in subjects with intraoral halitosis after several applications under normal conditions of use. Methods: In this randomized clinical trial with mouth rinse and toothpaste, single-center, double-blinded, parallel participants were assigned to an experimental group (Lacer Hali^TM,, n = 20), a positive control group (Halita^TM, n = 20), and a placebo group (n = 20). The active duration of the study was 18 days. The clinical follow-up evaluations were performed at five time points (T0, T1, T2, T3, and T4). The intensity of halitosis was evaluated by organoleptic measurement and the portable gas chromatograph OralChroma^TM. The data were analyzed using generalized mixed linear models. Results: Sixty patients completed the study. Lacer Hali^TM, in comparison with Halita^TM, did not show statistically significant differences at any time during the study except for the levels of hydrogen sulfide and total volatile sulfur compounds at 15 days, where Halita^TM was better. Compared to the placebo treatment, Lacer Hali^TM, was significantly more efficient, in terms of both the organoleptic evaluations at 8 days and the levels of hydrogen sulfide. Conclusions: Lacer Hali^TM is an alternative to chlorhexidine-based toothpaste and mouthwashes in the management of halitosis.

Recent update on potential cytotoxicity, biocompatibility and preventive measures of biomaterials used in dentistry

Dental treatment is provided for a wide variety of oral health problems like dental caries, periodontal diseases, periapical infections, replacement of missing teeth and orthodontic problems. Various biomaterials, like composite resins, amalgam, glass ionomer cement, acrylic resins, metal alloys, impression materials, bone grafts, membranes, local anaesthetics, etc., are used for dental applications. The physical and chemical characteristics of these materials influence the outcome of dental treatment. It also impacts on the biological, allergic and toxic potential of biomaterials. With innovations in science and their positive results, there is also a need for awareness about the biological risks of these biomaterials. The aim of dental treatment is to have effective, yet safe, and long-lasting results for the benefit of patients. For this, it is important to have a thorough understanding of biomaterials and their effects on local and systemic health. Materials used in dentistry undergo a series of analyses before their oral applications. To the best of our knowledge, this is the first and original review that discusses the reasons for and studies on the toxicity of commonly used biomaterials for applications in dentistry. It will help clinicians to formulate a methodical approach for the selection of dental biomaterials, thus providing an awareness for forecasting their risk of toxic reactions.

Use of chlorhexidine to eradicate oropharyngeal SARS-CoV-2 in COVID-19 patients

As public distribution of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is underway, prevention of coronavirus disease 2019 (COVID‐19) relies on minimizing spread. In this study, chlorhexidine gluconate was investigated as a topical antimicrobial agent against SARS‐CoV‐2. This was a randomized, prospective cohort study using chlorhexidine as an oral rinse and posterior oropharyngeal spray in hospitalized COVID‐19 patients. The primary outcome was presence or absence of laboratory‐confirmed SARS‐CoV‐2 in the oral and oropharyngeal cavities after 4 days of chlorhexidine use and standard of care (study group) or standard of care only (control group). SARS‐CoV‐2 was eliminated from the oropharynx in 62.1% of patients who used chlorhexidine as an oral rinse, versus 5.5% of the control group patients. Among patients who used a combination of oral rinse and oropharyngeal spray, 86.0% eliminated oropharyngeal SARS‐CoV‐2, versus 6.3% of control patients. Chlorhexidine is a simple and safe addition to current COVID‐19 prevention guidelines and may play a significant role in reducing disease spread.

Chlorhexidine is a simple and safe addition to the current COVID‐19 prevention guidelines.

When used with vaccination, proper social distancing, mask wearing, and hand hygiene, chlorhexidine may contribute to a more robust disease prevention regimen.

The salivary pellicle on dental biomaterials

The salivary pellicle, an adlayer formed by adsorption of salivary components on teeth and dental biomaterials, has direct consequences on basic outcomes of dentistry. Here, we provide an overview of salivary pellicle formation processes with a critical focus on dental biomaterials. We describe and critique the array of salivary pellicle measurement techniques. We also discuss factors that may affect salivary pellicle formation and the heterogeneity of the published literature describing salivary pellicle formation on dental biomaterials. Finally, we survey the many effects salivary pellicles have on dental biomaterials and highlight its implications on design criteria for dental biomaterials. Future investigations may lead to rationally designed dental biomaterials to control the salivary pellicle and enhance material function and patient outcomes.

A Novel Small Molecule, LCG-N25, Inhibits Oral Streptococcal Biofilm

Dental caries is a chronic oral infectious disease caused by cariogenic biofilm adhered on the tooth surface. Our previous study demonstrated that a repurposed natural compound napabucasin (NAP) showed good antimicrobial activity against oral streptococcal biofilms. The current study designed a novel small molecule, namely LCG-N25, using NAP as a lead compound, and aimed to investigate its potential as an antimicrobial agent in the control of dental caries. LCG-N25 was designed and synthesized with reference to the structure of NAP. The minimal inhibitory concentrations and the minimal bactericidal concentrations of LCG-N25 against Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii were evaluated by microdilution method. The antimicrobial activity of LCG-N25 was further evaluated by crystal violet staining, colony forming units counting, biofilm metabolism assay, dead/live fluorescent staining, and scanning electron microscopy. The effect of LCG-N25 on the extracellular polysaccharides of biofilms was determined by both anthrone-sulfuric acid method and fluorescent staining. The microbial composition of streptococcal biofilms after LCG-N25 treatment was further visualized and quantified by fluorescence in situ hybridization. Besides, the cytotoxicity of LCG-N25 was evaluated by Cell Counting Kit-8 assay, and repeated exposure of S. mutans to LCG-N25 treatment was performed to assess if this novel compound could induce drug resistance of this cariogenic bacterium. We found that LCG-N25 exhibited a good antibacterial activity, low-cytotoxicity, and did not induce drug resistance of cariogenic S. mutans. These findings suggest that LCG-N25 may represent a promising antimicrobial agent that can be used as an adjuvant to the management of dental caries.

Metabolic activity of hydro-carbon-oxo-borate on a multispecies subgingival periodontal biofilm: a short communication

Objective

This study evaluated the metabolic activity of hydro-carbon-oxo-borate complex (HCOBc) on a multispecies subgingival biofilm as well as its effects on cytotoxicity.

Materials and methods

The subgingival biofilm with 32 species related to periodontitis was formed in the Calgary Biofilm Device (CBD) for 7 days. Two different therapeutic schemes were adopted: (1) treatment with HCOBc, 0.12% chlorhexidine (CHX), and negative control group (without treatment) from day 3 until day 6, two times a day for 1 min each time, totaling 8 treatments and (2) a 24-h treatment on a biofilm grown for 6 days. After 7 days of formation, biofilm metabolic activity was determined by colorimetry assay, and bacterial counts and proportions of complexes were determined by DNA-DNA hybridization. Both substances’ cytotoxicity was evaluated by cell viability (XTT assay) and clonogenic survival assay on ovary epithelial CHO-K1 cells and an osteoblast precursor from calvaria MC3T3-E1 cells.

Results

The first treatment scheme resulted in a significant reduction in biofilm’s metabolic activity by means of 77% by HCOBc and CHX treatments versus negative control. The total count of 11 and 25 species were decreased by treatment with hydro-carbon-oxo-borate complex and CHX, respectively, compared with the group without treatment (p < 0.05), highlighting a reduction in the levels of Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, and Fusobacterium periodontium. CHX significantly reduced the count of 10 microorganisms compared to the group treated with HCOBc (p < 0.05). HCOBc and CHX significantly decreased the pathogenic red-complex proportion compared with control-treated biofilm, and HCOBc had even a more significant effect on the red complex than CHX had (p ≤ 0.05). For the second treatment scheme, HCOBc complex and CHX significantly decreased 61 and 72% of control biofilms’ metabolic activity and the counts of 27 and 26 species, respectively. HCOBc complex did not significantly affect the proportions of formed biofilms, while CHX significantly reduced red, orange, and yellow complexes. Both substances exhibited similar cytotoxicity results.

Conclusions

This short communication suggested that the HCOBc complex reduced a smaller number of bacterial species when compared to chlorhexidine during subgingival biofilm formation, but it was better than chlorhexidine in reducing red-complex bacterial proportions. Although HCOBc reduced the mature 6-day-old subgingival multispecies biofilms, it did not modify bacterial complexes’ ratios as chlorhexidine did on the biofilms mentioned above. Future in vivo studies are needed to validate these results.

Clinical relevance

HCOBc complex could be used to reduce red-complex periodontal bacterial proportions.

Long-Term Comparison of Survival and Marginal Bone of Implants with and without Sinus Augmentation in Maxillary Molars within the Same Patients: A 5.8- to 22-Year Retrospective Study

Maxillary sinus floor augmentation (MSFA) is widely used and considered a predictable procedure for implant placement. However, the influence of MSFA on implant survival and marginal bone loss (MBL) is still inconclusive. The purpose of this retrospective observational study is to evaluate the long-term genuine influence of MSFA on the survival and MBL of implants by comparing those with and without MSFA only in maxillary molars within the same patients. Thirty-eight patients (28 male and 10 female), with a total of 119 implants, received implants with and without MSFA, and were followed up for 5.8 to 22 years. Patient- and implant-related factors were assessed with a frailty model for implant survival and with generalized estimation equations (GEE) for MBL around the implant. No variables showed a statistical significance for implant failure in the frailty model. In GEE analysis for MBL, MSFA did not show any statistical significance. In conclusion, MSFA demonstrated no significant influence on implant failure and MBL in posterior maxilla in this study.

Biguanides: Species with versatile therapeutic applications

Biguanides are compounds in which two guanidine moieties are fused to form a highly conjugated system. Biguanides are highly basic and hence they are available as salts mostly hydrochloride salts, these cationic species have been found to exhibit many therapeutic properties. This review covers the research and development carried out on biguanides and accounts the various therapeutic applications of drugs containing biguanide group-such as antimalarial, antidiabetic, antiviral, anticancer, antibacterial, antifungal, anti-tubercular, antifilarial, anti-HIV, as well as other biological activities. The aim of this review is to compile all the medicinal chemistry applications of this class of compounds so as to pave way for the accelerated efforts in finding the drug action mechanisms associated with this class of compounds. Importance has been given to the organic chemistry of these biguanide derivatives also.

Effects of Octenidine on the Formation and Disruption of Dental Biofilms: An Exploratory In Situ Study in Healthy Subjects

Dental biofilms are highly structured, complex multispecies communities that, if left untreated, lead to severe oral complications such as caries and periodontal diseases. Therefore, antibiofilm agents are often recommended for both preventive and therapeutic measures. However, biofilm management can be challenging due to the low sensitivity of biofilms to antimicrobial treatments. Octenidine dihydrochloride (OCT) is a highly effective antibacterial agent. Because the OCT antibiofilm efficacy has not been studied in situ, this exploratory crossover study aimed to evaluate the effects of OCT mouth rinsing on biofilm formation and on the disruption of mature biofilms. Moreover, a comparison to the gold-standard chlorhexidine (CHX) was conducted. The biofilms were formed intraorally by 5 healthy volunteers on enamel specimens fixed to acrylic splints. For biofilm formation analysis, OCT, CHX, or water rinses were applied for 30 s every 12 h. The samples evaluation took place at 24-and 48-h time points. For biofilm disruption analysis, sample assessment was performed before and directly after the first OCT or CHX rinse on 48-h mature biofilms. A second rinse was carried out 12 h later. The last assessment was applied to 72-h mature biofilms. The biofilms were analyzed by fluorescence microscopy and transmission electron microscopy. The results showed OCT significantly reducing biofilm formation and bacterial vitality in situ. Simultaneously, the biofilm thickness was strongly decreased. Moreover, a single application of OCT to a 48-h mature biofilm induced substantial biofilm disruption. In addition, the efficacy of OCT compared favorably to CHX. These findings show that OCT rinses prevent biofilm formation and disrupt preexisting mature biofilms formed by healthy subjects. This work suggests that OCT might be used for dental biofilm management as a part of the medical treatment of oral diseases. Future studies with a larger subject heterogeneity and number are needed to confirm the observed OCT effects.

Resilience of the oral microbiome

The human mouth harbors a complex microbiota, the composition of which is potentially influenced by a wide range of factors, including the intake of food and drink, the availability of endogenous nutrients, the host immune system, drug treatments, and systemic diseases. Despite these possible influences, the oral microbiota is remarkably resilient, particularly in comparison with the microbiota of the large intestine. Diet, with the exception of excessive and/or frequent consumption of fermentable carbohydrate or supplementation with nitrate, has minimal impact on the composition of the oral bacterial community. The common oral diseases dental caries and the periodontal diseases is associated with modification of the oral microbiota primarily as a result of the ecological changes induced by excessive acid production and inflammation, respectively. Systemically-administered antimicrobials have only a small effect on the composition of the oral bacterial community, and while locally delivered antimicrobials can have some clinical benefits, the biofilm lifestyle of oral bacteria lends them substantial resistance to the agents used. Saliva plays an important role in oral microbial ecology, by supplying nutrients and providing protection against colonization by nonoral organisms. Dry mouth is one condition that has a major effect on the microbiota, resulting in increased colonization by opportunistic pathogens. Some systemic diseases do affect the oral microbiome, notably diabetes, in which raised levels of glucose in saliva and tissue impact on bacterial nutrition.

Efficacy of Mouth Rinses Against SARS-CoV-2: A Scoping Review

Introduction:The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in saliva and nasopharyngeal secretions has challenged the routine practice of dentistry. Use of preprocedural mouth rinses has been recommended by several organizations to potentially reduce the transmission of SARS-CoV-2. This scoping review aimed at evaluating the available evidence on the efficacy of mouth rinses against SARS-CoV-2.

Methods:A thorough literature search on electronic databases (PubMed, Scopus, and Google Scholar) was performed by two independent reviewers and data from articles addressing the aim of this article were extracted.

Results:After exclusion of articles not addressing the end point in question, 12 articles were included in this scoping review. Of the 12 articles, seven werein vitrostudies and five werein vivohuman clinical studies. Thein vitrostudies used a standardized methodology (endpoint dilution assay) to evaluate the efficacy of antimicrobial mouth rinses against SARS-CoV-2. Thein vivostudies were done utilizing polymerase chain reaction assay of samples obtained from saliva or nasopharyngeal swab or a combination of both nasopharyngeal and oropharyngeal swab. The reagents tested in these studies included povidone-iodine, chlorhexidine, hydrogen peroxide (H2O2), essential oils, and quaternary ammonium compounds and demonstrated varied efficacy against SARS-CoV-2.

Conclusion:Based on the available evidence fromin vitrostudies, it can be concluded that mouth rinses have a potential to reduce SARS-CoV-2 viral load; however, effectiveness inin vivoconditions is still inconclusive. Owing to the substantial heterogeneity in reporting of the anti–SARS-CoV-2 efficacy of mouth rinses, this review highlights the need to conduct future research with robust and standardized methodologies to confirm effectiveness of mouth rinses.

Effect of a chlorhexidine-encapsulated nanotube modified pit-and-fissure sealant on oral biofilm

The purpose of this study was to characterize a chlorhexidine-encapsulated nanotube modified pit-and-fissure sealant for biofilm development prevention. HS (commercial control); HNT (HS+15wt%Halloysite^®-clay-nanotube); CHX10% (HS+15wt% HNT-encapsulated with chlorhexidine 10%); and CHX20% (HS+15wt% HNT-encapsulated with CHX20%) were tested. Degree-of-conversion (DC%), Knoop hardness (KHN), and viscosity were analyzed. The ability of the sealant to wet the fissures was evaluated. Specimens were tested for zones of inhibition of microbial growth. S. mutans biofilm was tested by measuring recovered viability. Data were statistically analyzed (p<0.05). DC% was significantly higher for the HNT-CHX groups. For KHN, CHX10% presented a lower mean value than the other groups. Adding HNT resulted in higher viscosity values. The biofilm on CHX10% and CHX20% sealants presented remarkable CFU/mL reduction in comparison to the HS. The experimental material was able to reduce the biofilm development in S. mutans biofilm without compromising the sealant properties.

Clinical Efficacy of Chlorhexidine as an Adjunct to Mechanical Therapy of Peri-Implant Disease: A Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to determine the efficacy of chlorhexidine (CHX) as an adjunctive therapy to mechanical debridement in the treatment of peri-implant diseases. Five databases (PubMed, EMBASE, Cochrane Central Register of Controlled Trails, Web of Science, and ClinicalTrials.gov) were searched. Randomized controlled trials (RCTs) comparing mechanical debridement combined with CHX to mechanical debridement alone for patients with peri-implant disease were identified. The trial investigators evaluated factors indicating inflammatory levels, including bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL). Six RCTs with 207 patients were ultimately included in this review. Low- to moderate-quality evidence demonstrated that the adjunctive CHX therapy had no significant effect on BOP reduction within 1 month (mean difference [MD], 0.10; 95% confidence interval [CI], -0.06 to 0.25), 3-4 months (MD, 0.06; 95% CI, -0.03 to 0.15), and 6-8 months (MD, 0.06; 95% CI, -0.03 to 0.14) of follow-up. Significant differences in PD reduction and CAL gain were also not found. Although 1 subgroup analysis revealed a significant result (MD, 009; 95% CI, 0.01-0.18) for the use of CHX solution, this could be interpreted as clinically slight. Based on available evidence, adding CHX to mechanical debridement, compared with mechanical debridement alone, did not significantly enhance the clinical results. Therefore, clinicians should consider the negligible effect of adjunctive CHX.

Cavity Disinfection With a 445 nm Diode Laser Within the Scope of Restorative Therapy - A Pilot Study

Introduction: Cavity disinfection is necessary to prevent a progressive infection of the crown dentin and pulp. Increasing intolerance and resistance to antiseptics and antibiotics as well as the controversy over the effects of those on the dental hard tissue and composite have prompted the investigation of alternative treatment options. The objective of this pilot study is to evaluate the antibacterial potential of a diode laser with a wavelength of 445 nm in the cavity preparation using the bacterium Streptococcus salivarius associated with caries in conjunction with the characteristics and influences of dentin on light transmission. Methods: The bactericidal effect of the laser irradiation was determined in culture experiments by using caries-free human dentin samples on bacteria-inoculated agar. For this, dentin discs (horizontally cut coronal dentin) of 500 µm and 1000 µm thicknesses were produced and irradiated with the laser with irradiation parameters of 0.7-1 W in a cw-mode and exposure times of between 5-30 s. Based on the different sample thicknesses, the penetration depth effect of the irradiation was ascertained after the subsequent incubation of the bacteria-inoculated agar. Additional influential parameters on the irradiation transmission were investigated, including surface moisture, tooth color as well as the presence of a smear layer on the dentin surface. Results: The optical transmission values of the laser radiation for dentin were significantly dependent on the sample thickness (P = 0.006) as well as its moisture content (P = 0.013) and were independent of the presence of a smear layer. There was a 40% reduction in bacteria after the radiography of the 500-µm-thick dentin samples, which was shown as the lowest laser dose (443 J/cm²). Conclusion: These findings indicate that the diode laser with light emission at a wavelength of 445 nm is interesting for the supportive cavity disinfection within the scope of caries therapy and show potential for clinical applications.

A sugarcane cystatin (CaneCPI-5) alters microcosm biofilm formation and reduces dental caries

The antimicrobial and anticaries effects of CaneCPI-5 were evaluated. Ninety bovine enamel samples were treated for 60 s with either phosphate-buffered-saline (PBS), 0.12% chlorhexidine (CHX), 0.05 mg ml^-1 CaneCPI-5, 0.1 mg ml^-1 CaneCPI-5 or 0.5 mg ml^-1 CaneCPI-5. They were incubated with inoculum (human saliva + McBain's saliva) for the first 8 h. From then until the end of the experiment, the enamel was exposed to McBain saliva with sucrose and, once a day, for 5 days, they were treated with the solutions. At the end of the experimental period, resazurin and viable plate count assays were performed. Enamel demineralization was also measured. All concentrations of CaneCPI-5 and CHX significantly reduced the activity of biofilms compared with PBS. For viable plate counts, all treatments similarly reduced the lactobacilli and total streptococci; for the mutans streptococci, 0.05 mg ml^-1 CaneCPI-5 performed better than CHX. All CaneCPI-5 concentrations significantly reduced the integrated mineral loss. This study represents the first step regarding the use of CaneCPI-5 within the concept of acquired enamel pellicle and biofilm engineering to prevent dental caries.

Combination of toothbrushing and chlorhexidine compared with exclusive use of chlorhexidine to reduce the risk of ventilator-associated pneumonia: A systematic review with meta-analysis

This study aimed to compare the effectiveness of 0.12% chlorhexidine alone and 0.12% chlorhexidine in combination with toothbrushing to prevent ventilator-associated pneumonia (VAP) in mechanically ventilated patients. The Embase, Latin American and Caribbean Health Science Literature, PubMed, Scientific Electronic Library Online, Scopus, LIVIVO, Web of Science, Cochrane Library, OpenThesis, and Open Access Thesis and Dissertations databases were used. Only randomized controlled trials without restrictions on the year or language of publication were included. Two reviewers assessed the risk of bias using the Joanna Briggs Institute Critical Appraisal Tool. A meta-analysis using a random-effects model estimated the combined relative risk (RR). The Grading of Recommendations, Assessment, Development and Evaluations approach was used to assess the certainty of the evidence. Initially, 2,337 studies were identified, of which 4 were considered in the systematic review and 3 in the meta-analysis (total sample: 796 patients). The studies were published between 2009 and 2017. All eligible studies had a low risk of bias. The meta-analysis revealed that the risk of VAP was 24% lower in patients receiving chlorhexidine combined with toothbrushing than in those receiving chlorhexidine alone (RR: 0.76; 95% confidence interval: 0.55-1.06), with moderate certainty of evidence and without statistical significance. In conclusion, considering the limitations of this study, a standard protocol for the prevention of VAP is not yet recommended. More studies with larger sample sizes are needed to draw strong conclusions. However, considering that toothbrushing is a simple intervention, it should be a common practice in mechanically ventilated patients, especially among patients with coronavirus disease.

Repurposing Napabucasin as an Antimicrobial Agent against Oral Streptococcal Biofilms

Objectives

Disruption of microbial biofilms is an effective way to control dental caries. Drug resistance and side effects of the existing antimicrobials necessitate the development of novel antibacterial agents. The current study was aimed at investigating the antibacterial activities of the repurposed natural compound napabucasin against oral streptococci.

Methods

The minimum inhibitory concentration, minimum bactericidal concentration, minimum biofilm inhibition concentration, and minimum biofilm reduction concentration of Streptococcus mutans, Streptococcus gordonii, and Streptococcus sanguinis were examined by a microdilution method. Cytotoxicity of napabucasin against human oral keratinocytes, human gingival epithelia, and macrophage RAW264.7 was evaluated by CCK8 assays. The dead/live bacterium and exopolysaccharide in the napabucasin-treated multispecies biofilms were evaluated by confocal laser scanning microscopy. Microbial composition within the napabucasin-treated biofilms was further visualized by fluorescent in situ hybridization and qPCR. And the cariogenicity of napabucasin-treated biofilms was evaluated by transverse microradiography.

Results

Napabucasin exhibited good antimicrobial activity against oral streptococcal planktonic cultures and biofilms but with lessened cytotoxicity as compared to chlorhexidine. Napabucasin reduced the cariogenic S. mutans and increased the proportion of the commensal S. gordonii in the multispecies biofilms. More importantly, napabucasin significantly reduced the demineralization capability of biofilms on tooth enamels.

Conclusion

Napabucasin shows lessened cytotoxicity and comparable antimicrobial effects to chlorhexidine. Repurposing napabucasin may represent a promising adjuvant for the management of dental caries.

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

Objectives

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

Methods

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

Results

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

Conclusions and clinical relevance

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

Electronic supplementary material

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

Limited antimicrobial efficacy of oral care antiseptics in microcosm biofilms and phenotypic adaptation of bacteria upon repeated exposure

Objectives

The aims of this study were to investigate the antimicrobial efficacy of antiseptics in saliva-derived microcosm biofilms, and to examine phenotypic adaption of bacteria upon repeated exposure to sub-inhibitory antiseptic concentrations.

Methods

Saliva-derived biofilms were formed mimicking caries- or gingivitis-associated conditions, respectively. Microbial compositions were analyzed by semiconductor-based 16S rRNA sequencing. Biofilms were treated with CHX, CPC, BAC, ALX, and DQC for 1 or 10 min, and colony forming units (CFU) were evaluated. Phenotypic adaptation of six selected bacterial reference strains toward CHX, CPC, and BAC was assessed by measuring minimum inhibitory concentrations (MICs) over 10 passages of sub-inhibitory exposure. Protein expression profiles were investigated by SDS-PAGE.

Results

Both biofilms showed outgrowth of streptococci and Veillonella spp., while gingivitis biofilms also showed increased relative abundances of Actinomyces, Granulicatella, and Gemella spp. Antiseptic treatment for 1 min led to no relevant CFU-reductions despite for CPC. When treated for 10 min, CPC was most effective followed by BAC, ALX, CHX, and DQC. Stable adaptations with up to fourfold MIC increases were found in E. coli toward all tested antiseptics, in E. faecalis toward CHX and BAC, and in S. aureus toward CPC. Adapted E. coli strains showed different protein expression as compared with the wildtype strain.

Conclusion

Antiseptics showed limited antimicrobial efficacy toward mature biofilms when applied for clinically relevant treatment periods. Bacteria showed phenotypic adaptation upon repeated sub-inhibitory exposure.

Clinical relevance

Clinicians should be aware that wide-spread use of antiseptics may pose the risk of inducing resistances in oral bacteria.