Effects of a chlorhexidine gluconate-containing mouthwash on the vitality and antimicrobial susceptibility of in vitro oral bacterial ecosystems

Investigating oral microbiome dynamics in chronic kidney disease and post-transplantation in continuous culture

The oral microbiome is influenced by environmental factors in chronic kidney disease and following kidney transplantation affecting microbial composition, which may have implications for health and recovery. A major driver of oral microbiome perturbation is the accumulation of urea in saliva. We have modelled increased salivary urea concentrations associated with CKD and subsequent reductions that may occur post-transplantation. Oral microbiota were established in constant-depth film fermenters by inoculation with saliva. Duplicate validation runs were maintained with artificial saliva with baseline urea concentrations (0.205 mg/mL) for 21 days. Triplicate treatment runs were then done with baseline urea for 10 days (healthy phase) before urea was increased for 10 days to reflect CKD concentrations (0.92 mg/mL) (CKD phase). This was followed by reversion to baseline urea concentrations (post-transplant phase). Biofilms in primary validation runs reached dynamic stability within 5 days according to viable counting. DNA sequence data indicated minimal taxonomic variation over time and between low and high urea treatments despite background noise indicating changes in bacteria belonging to the family Gemellaceae and the genera TG5 and Leptotrichia. Significant differences in alpha and beta diversity occurred between low and high urea states but not following reversion to a low urea environment. Increased abundance of the TG5 was detected in late model phases, despite apparent count stability, and independent of changes in urea concentrations.

IMPORTANCE

This study investigates dynamic changes in the oral microbiome associated with changes in salivary urea concentration, an important factor in chronic kidney disease (CKD). The in vitro system modeled increased urea concentrations and subsequent reductions post-transplantation. The study provides insight into the oral microbial shifts during different simulated clinical phases. Understanding these dynamics is crucial for advancing our comprehension of CKD-associated oral microbiome variations and their potential impact on patient well-being and recovery.

Real-time flow cytometry to assess qualitative and quantitative responses of oral pathobionts during exposure to antiseptics

Antiseptics are widely used in oral healthcare to prevent or treat oral diseases, such as gingivitis and periodontitis. However, the incidence of bacteria being tolerant to standard antiseptics has sharply increased over the last few years. This stresses the urgency for surveillance against tolerant organisms, as well as the discovery of novel antimicrobials. Traditionally, susceptibility to antimicrobials is assessed by broth micro-dilution or disk diffusion assays, both of which are time-consuming, labor-intensive, and provide limited information on the mode of action of the antimicrobials. The abovementioned limitations highlight the need for the development of new methods to monitor and further understand antimicrobial susceptibility. In this study, we used real-time flow cytometry, combined with membrane permeability staining, as a quick and sensitive technology to study the quantitative and qualitative responses of two oral pathobionts to different concentrations of chlorhexidine (CHX), cetylpyridinium chloride (CPC), or triclosan. Apart from the real-time monitoring of cell damage, we further applied a phenotypic fingerprinting method to differentiate between the bacterial subpopulations that arose due to treatment. We quantified the pathobiont damage rate of different antiseptics at different concentrations within 15 minutes of exposure and identified the conditions under which the bacteria were most susceptible. Moreover, we detected species-specific and treatment-specific phenotypic subpopulations. This proves that real-time flow cytometry can provide information on the susceptibility of different microorganisms in a short time frame while differentiating between antiseptics and thus could be a valuable tool in the discovery of novel antimicrobial compound, while at the same time deciphering their mode of action.

IMPORTANCE

With increasing evidence that microorganisms are becoming more tolerant to standard antimicrobials, faster and more accessible antimicrobial susceptibility testing methods are needed. However, traditional susceptibility assays are laborious and time-consuming. To overcome the abovementioned limitations, we introduce a novel approach to define antimicrobial susceptibility in a much shorter time frame with the use of real-time flow cytometry. Furthermore, phenotypic fingerprinting analysis can be applied on the data to study the way antiseptics affect the bacterial cell morphology over time and, thus, gain information on the mode of action of a certain compound.

Supra- and Subgingival Microbiome in Gingivitis and Impact of Biofilm Control: A Comprehensive Review

This comprehensive review aimed (1) to characterize the sub- and supragingival microbiome in patients with biofilm-induced gingivitis (including experimental gingivitis), (2) to assess its stability and evolution over time, and (3) to assess the impact of biofilm control measures on this stability. An electronic search of the MEDLINE®/PubMed® database until December 2023 was conducted. NCBI Taxonomy, eHOMD 16S rRNA Reference Sequence, and Tree Version 15.23 databases were used to standardize taxonomic nomenclature. Out of 89 papers initially retrieved, 14 studies were finally included: 11 using experimental gingivitis as a model and three randomized clinical trials evaluating the impact of biofilm control measures. Among them, five characterized the subgingival microbiome, nine the supragingival microbiome, and one both the sub- and supragingival microbiome. In addition, five studies evaluated the effect of toothpaste, and four studies evaluated the effect of mouth rinses. The diversity and structure of the microbiome differed significantly between patients with periodontal health and those with biofilm-induced gingivitis (including experimental gingivitis). Those differences were not reversed through conventional oral hygiene measures. Specific antiseptic agents, especially if delivered as mouth rinses, may have an impact on the supra- and subgingival microbiome in gingivitis.

Unveiling potential repurposed drug candidates for Plasmodium falciparum through in silico evaluation: A synergy of structure-based approaches, structure prediction, and molecular dynamics simulations

The rise of drug resistance in Plasmodium falciparum, rendering current treatments ineffective, has hindered efforts to eliminate malaria. To address this issue, the study employed a combination of Systems Biology approach and a structure-based pharmacophore method to identify a target against P. falciparum. Through text mining, 448 genes were extracted, and it was discovered that plasmepsins, found in the Plasmodium genus, play a crucial role in the parasite's survival. The metabolic pathways of these proteins were determined using the PlasmoDB genomic database and recreated using CellDesigner 4.4.2. To identify a potent target, Plasmepsin V (PF13_0133) was selected and examined for protein-protein interactions (PPIs) using the STRING Database. Topological analysis and global-based methods identified PF13_0133 as having the highest centrality. Moreover, the static protein knockout PPIs demonstrated the essentiality of PF13_0133 in the modeled network. Due to the unavailability of the protein's crystal structure, it was modeled and subjected to a molecular dynamics simulation study. The structure-based pharmacophore modeling utilized the modeled PF13_0133 (PfPMV), generating 10 pharmacophore hypotheses with a library of active and inactive compounds against PfPMV. Through virtual screening, two potential candidates, hesperidin and rutin, were identified as potential drugs which may be repurposed as potential anti-malarial agents.

Ingredients in Commercially Available Mouthwashes

OBJECTIVES

Mouthwashes, a cornerstone of oral and dental hygiene, play a pivotal role in combating the formation of dental plaque, a leading cause of periodontal disease and dental caries. This study aimed to review the composition of mouthwashes found on retail shelves in Turkey and evaluate their prevalence and side effects, if any.

METHODS

The mouthwashes examined were sourced from the 5 largest chain stores in each district of Istanbul. A comprehensive list of the constituents was meticulously recorded. The research was supported by an extensive compilation of references from scholarly databases such as Google Scholar, PubMed, and ScienceDirect. Through rigorous analysis, the relative proportions of mouthwash ingredients and components were determined.

RESULTS

A total of 45 distinctive variations of mouthwashes, representing 17 prominent brands, were identified. Amongst the 116 ingredients discovered, 70 were evaluated for potential adverse effects and undesirable side effects. The aroma of the mouthwash (n = 45; 100%), as welll as their sodium fluoride (n = 28; 62.22%), sodium saccharin (n = 29; 64.44%), sorbitol (n = 21; 46.6%), and propylene glycol (n = 28; 62.22%) content were the main undesireable features.

CONCLUSIONS

The limited array of mouthwashes found on store shelves poses a concern for both oral and public health. Furthermore, the intricate composition of these products, consisting of numerous ingredients with the potential for adverse effects, warrants serious attention. Both clinicians and patients should acknowledge the importance and unwarranted side effects of the compnents of the mouthwashes.

Short-term effects of Chlorhexidine mouthwash and Listerine on oral microbiome in hospitalized patients

Introduction

Chlorhexidine (CHX) and essential oil containing mouthwashes like Listerine^® can improve oral hygiene via suppressing oral microbes. In hospitalized patients, CHX mouthwash reduces the incidence of ventilator-associated pneumonia. However, CHX use was also associated with increased mortality, which might be related to nitrate-reducing bacteria. Currently, no study determines oral bacteria targeted by essential oils mouthwash in hospitalized patients using a metagenomic approach.

Methods

We recruited 87 hospitalized patients from a previous randomized control study, and assigned them to three mouthwash groups: CHX, Listerine, and normal saline (control). Before and after gargling the mouthwash twice a day for 5-7 days, oral bacteria were examined using a 16S rDNA approach.

Results

Alpha diversities at the genus level decreased significantly only for the CHX and Listerine groups. Only for the two groups, oral microbiota before and after gargling were significantly different, but not clearly distinct. Paired analysis eliminated the substantial individual differences and revealed eight bacterial genera (including Prevotella, Fusobacterium, and Selenomonas) with a decreased relative abundance, while Rothia increased after gargling the CHX mouthwash. After gargling Listerine, seven genera (including Parvimonas, Eubacterium, and Selenomonas) showed a decreased relative abundance, and the magnitudes were smaller compared to the CHX group. Fewer bacteria targeted by Listerine were reported to be nitrate-reducing compared to the CHX mouthwash.

Discussion

In conclusion, short-term gargling of the CHX mouthwash and Listerine altered oral microbiota in our hospitalized patients. The bacterial genera targeted by the CHX mouthwash and Listerine were largely different and the magnitudes of changes were smaller using Listerine. Functional alterations of gargling CHX and Listerine were also different. These findings can be considered for managing oral hygiene of hospitalized patients.

Comparative Evaluation of Antimicrobial, Antiamoebic, and Antiviral Efficacy of Ophthalmic Formulations

The extensive use of ophthalmic antibiotics is contributing to the appearance of resistant bacterial strains, which require prolonged and massive treatments with consequent detrimental outcomes and adverse effects. In addition to these issues, antibiotics are not effective against parasites and viruses. In this context, antiseptics could be valuable alternatives. They have nonselective mechanisms of action preventing bacterial resistance and a broad spectrum of action and are also effective against parasites and viruses. Here, we compare the in vitro antibacterial, antiameobic, and antiviral activities of six ophthalmic formulations containing antiseptics such as povidone-iodine, chlorhexidine, and thymol against Gram-positive and Gram-negative bacteria, the amoeba Acanthamoeba castellanii, and two respiratory viruses, HAdV-2 and HCoV-OC43. The results suggest that, among all the tested formulations, Dropsept, consisting of Vitamin E TPGS-based (tocopheryl polyethylene glycol succinate) in combination with the antiseptic chlorhexidine, is the one with the highest range of activities, as it works efficiently against bacteria, amoeba, and viruses. On the other hand, the solution containing PVA (polyvinyl alcohol) and thymol showed a promising inhibitory effect on Pseudomonas aeruginosa, which causes severe keratitis. Given its high efficiency, Dropsept might represent a valuable alternative to the widely used antibiotics for the treatment of ocular infections. In addition to this commercial eye drop solution, thymol-based solutions might be enrolled for their natural antimicrobial and antiamoebic effect.

The Effect of Pimpinella Anisum and Origanum Vulgare Extracts Against Streptococcus Sanguinis, Streptococcus Mutans, and Streptococcus Salivarius

Statement of the Problem

There are global efforts for introducing a new herbal antimicrobial agent with minimal side effects. There are some reports about the antimicrobial properties of Pimpinella anisum and Oregano Vulgare.

Purpose

In this study, the antimicrobial properties of Pimpinella anisum and Oregano Vulgare have been assessed.

Material and Method

In this experimental in vitro study, the dental plaque samples were collected from children aged 3 to 5 years old who were referred to a private dental office with diagnosis of dental caries. After determination of the bacterial colonies of Streptococcus sanguinis, Streptococcus mutans and Streptococcus salivarius, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethanolic and methanolic extracts of Pimpinella anisum and Oregano vulgare were measured by macrodilution and microdilution methods.

Results

The mean MIC and MBC of Pimpinella anisum extract and Oregano vulgare extract and their combination against Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius were statistically different (p< 0.001). The combination of these extracts showed the lowest MIC and MBC.

Conclusion

Hydroalcoholic extracts of the Pimpinella anisum and Oregano Vulgare were effective antibacterial agent against Streptococcus mutans, Streptococcus salivarius, and Streptococcus sanguinis so the combination of these two extracts showed the highest antibacterial properties on all the bacteria evaluated.

The Potential of α-Mangostin from Garcinia mangostana as an Effective Antimicrobial Agent-A Systematic Review and Meta-Analysis

This systematic review aims to evaluate the antimicrobial activity of α-mangostin derived from Garcinia mangostana against different microbes. A literature search was performed using PubMed and Science Direct until March 2022. The research question was developed based on a PICO (Population, Intervention, Control and Outcomes) model. In this study, the population of interest was microbes, α-mangostin extracted from Garcinia mangostana was used as exposure while antibiotics were used as control, followed by the outcome which is determined by the antimicrobial activity of α-mangostin against studied microbes. Two reviewers independently performed the comprehensive literature search following the predetermined inclusion and exclusion criteria. A methodological quality assessment was carried out using a scoring protocol and the risk of bias in the studies was analyzed. Reward screening was performed among the selected articles to perform a meta-analysis based on the pre-determined criteria. Case groups where α-mangostin extracted from Garcinia mangostana was incorporated were compared to groups using different antibiotics or antiseptic agents (control) to evaluate their effectiveness. A total of 30 studies were included; they were heterogeneous in their study design and the risk of bias was moderate. The results showed a reduction in microbial counts after the incorporation of α-mangostin, which resulted in better disinfection and effectiveness against multiple microbes. Additionally, the meta-analysis result revealed no significant difference (p > 0.05) in their effectiveness when α-mangostin was compared to commercially available antibiotics. α-mangostin worked effectively against the tested microbes and was shown to have inhibitory effects on microbes with antibiotic resistance.

Phenotypic Adaptation to Antiseptics and Effects on Biofilm Formation Capacity and Antibiotic Resistance in Clinical Isolates of Early Colonizers in Dental Plaque

Despite the wide-spread use of antiseptics in dental practice and oral care products, there is little public awareness of potential risks associated with antiseptic resistance and potentially concomitant cross-resistance. Therefore, the aim of this study was to investigate potential phenotypic adaptation in 177 clinical isolates of early colonizers of dental plaque (Streptococcus, Actinomyces, Rothia and Veillonella spp.) upon repeated exposure to subinhibitory concentrations of chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC) over 10 passages using a modified microdilution method. Stability of phenotypic adaptation was re-evaluated after culture in antiseptic-free nutrient broth for 24 or 72 h. Strains showing 8-fold minimal inhibitory concentration (MIC)-increase were further examined regarding their biofilm formation capacity, phenotypic antibiotic resistance and presence of antibiotic resistance genes (ARGs). Eight-fold MIC-increases to CHX were detected in four Streptococcus isolates. These strains mostly exhibited significantly increased biofilm formation capacity compared to their respective wild-type strains. Phenotypic antibiotic resistance was detected to tetracycline and erythromycin, consistent with the detected ARGs. In conclusion, this study shows that clinical isolates of early colonizers of dental plaque can phenotypically adapt toward antiseptics such as CHX upon repeated exposure. The underlying mechanisms at genomic and transcriptomic levels need to be investigated in future studies.

The efficiency of natural wound healing and bacterial biofilm inhibition of Aloe vera and Sodium Chloride toothpaste preparation

Background

Prevention is a preliminary focus of periodontitis treatment. Rather than giving complicated treatment to a periodontitis patient, a variety of toothpastes have been suggested to prevent periodontal disease progression. Herbal toothpastes containing natural plant components for maintaining or increasing healing might be a treatment modality for improving oral hygiene. Aloe vera is a medicinal plant with active ingredients that have antioxidant and anti-inflammatory effects. Additionally, increased sodium in the environment inhibits microorganism growth. A toothpaste containing salt and aloe vera may be an option to provide good oral hygiene.

Aim

To assess the in vitro cell migration of human gingival fibroblasts and antimicrobial effects of an herbal toothpaste containing A. vera and Sodium chloride.

Methods

The cytotoxicity of 0.02% or 0.2% toothpaste solution on human gingival fibroblast cell line was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The cell migration after treatment with 0.2% (v/v) toothpaste was determined using a Boyden Chamber assay. The effect of the toothpaste on inhibiting Porphylomonas gingivalis planktonic and biofilm growth was compared with Chlohexidine (CHX) using a Disk Diffusion and Biofilm susceptibility test, respectively. The results of the cytotoxicity assay, inhibition zone and percentage of live cells in the biofilm were statistically analyzed with One-way analysis of variance. Cell migration and biofilm inhibition were evaluated using the independent sample t-test and multiple t-test, respectively (p = 0.05).

Results

Neither test concentration of the toothpaste solution was toxic to the target cells. The 0.2% concentration was selected for the cell migration experiment. The herbal toothpaste formulation significantly increased cell migration compared with the control group (culture medium) (p = .02) The antimicrobial effect of this formulation on the P. gingivalis planktonic form was lower compared with 0.12% CHX (positive control group), however, it demonstrated greater P. gingivalis biofilm formation inhibition compared with the 0.12% CHX group.

Conclusions

The alternative use of an herbal toothpaste instead of a non-herbal toothpaste formulation should be considered for promoting oral health care. However, further clinical studies are necessary before it can be considered for patient use.

Disinfection efficacy and fracture strength of PMMA denture-based polymer with chlorhexidine, PDT utilizing Rose Bengal and hematoporphyrin, and Er, Cr: YSGG laser

OBJECTIVE

The study aimed to assess and compare disinfection efficacy and fracture strength of PMMA based DBPs using chlorhexidine (CHX), PDT utilizing Rose Bengal (RB) and hematoporphyrin HPD, and Er,Cr:YSGG laser (ECL) induced antimicrobial action against in-vitro biofilms colonized with C.albicans, S.aureus, S. mutans, and E. coli.

MATERIAL AND METHODS

American Type Culture Collection (ATCC) of C.albicans, S.aureus, S. mutans and E. coli were cultured. Forty-eight PMMA-based denture base plates (DBPs) were prepared by heat-cure acrylic resin and contaminated by in-vitro biofilm under-stimulated in-vitro conditions. DBPs were treated with group1; ECL group 2; RB 5µm, group 3; HPD 500 mg/L and group 4; 0.12% CHX (controls) respectively, for the disinfection of biofilms. All photosensitizers (PS) were activated by LED at a different wavelength. Each contaminated DBP was sprayed on all its surfaces with the aforementioned photosensitizers and CHX. One-way analysis of variance (ANOVA) was used to test the efficacy of disinfection and fracture load testing. Tukey multiple comparison tests were performed to compare means of CFU/mL (log10) for exposed E. coli, C. albicans, S aureus, and S. mutans.

RESULTS

Specimens in group 1 disinfected with erbium laser, group 3 disinfected with HPD, and group 4 sterilized with chemical disinfection were effective in decreasing bacterial load CFU/mL (log10) against C.albicans, S. aureus, S.mutans, and E. Coli (p>0.05). Intergroup comparison demonstrated ECL, CHX and HPD demonstrated a comparable reduction against C.albicans and S.aureus (p>0.05). Similarly, S.mutans and E.coli were sensitive against all experimental groups (p>0.05). no significant difference in fractural load analysis among the different investigated groups was noted (p>0.05).

CONCLUSION

ECL and HPD photosensitizer revealed a significant reduction in CFU/ml of exposed viable colonies of C.albicans, S.aureus, S. mutans, and E. coli comparable to 0.12% CHX mediated disinfection of PMMA-based DBPs. Irrespective of the type of disinfection no influence of disinfection was noted on the fracture load of PMMA DBPs.

Mucoadhesive controlled-release formulations containing morin for the control of oral biofilms

This study aimed to evaluate the antimicrobial and anti-biofilm activity of morin on polymicrobial biofilms and its cytotoxicity in controlled-release films and tablets based on gellan gum. Polymicrobial biofilms were formed from saliva for 48 h under an intermittent exposure regime to 1% sucrose and in contact with films or tablets of gellan gum containing 2 mg of morin each. Acidogenicity, bacterial viability, dry weight and insoluble extracellular polysaccharides from biofilms were evaluated. The cytotoxicity of morin was evaluated in oral keratinocytes. Morin released from the systems reduced the viability of all the microbial groups evaluated, as well as the dry weight and insoluble polysaccharide concentration in the matrix and promoted the control of acidogenicity when compared with the control group without the substance. Morin was cytotoxic only at the highest concentration evaluated. In conclusion, morin is an effective agent and shows antimicrobial and anti-biofilm activity against polymicrobial biofilms.

Low-Temperature Plasma as an Approach for Inhibiting a Multi-Species Cariogenic Biofilm

This study aimed to determine how low-temperature plasma (LTP) treatment affects single- and multi-species biofilms formed by Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii formed on hydroxyapatite discs. LTP was produced by argon gas using the kINPen09™ (Leibniz Institute for Plasma Science and Technology, INP, Greifswald, Germany). Biofilms were treated at a 10 mm distance from the nozzle of the plasma device to the surface of the biofilm per 30 s, 60 s, and 120 s. A 0.89% saline solution and a 0.12% chlorhexidine solution were used as negative and positive controls, respectively. Argon flow at three exposure times (30 s, 60 s, and 120 s) was also used as control. Biofilm viability was analyzed by colony-forming units (CFU) recovery and confocal laser scanning microscopy. Multispecies biofilms presented a reduction in viability (log10 CFU/mL) for all plasma-treated samples when compared to both positive and negative controls (p < 0.0001). In single-species biofilms formed by either S. mutans or S. sanguinis, a significant reduction in all exposure times was observed when compared to both positive and negative controls (p < 0.0001). For single-species biofilms formed by S. gordonii, the results indicate total elimination of S. gordonii for all exposure times. Low exposure times of LTP affects single- and multi-species cariogenic biofilms, which indicates that the treatment is a promising source for the development of new protocols for the control of dental caries.

Choosing the Right Essential Oil for a Mouthwash: Chemical, Antimicrobial and Cytotoxic Studies

Thirteen commercial essential oils were assessed for their possible inclusion in a mouthwash formulation based on their inhibitory effect against potentially pathogenic anaerobic oral bacterial isolates from subgingival plaque, and their cytotoxicity towards gingival cells. The essential oils, originating from species belonging to seven major aromatic plant families, were chosen to provide the necessary diversity in chemical composition that was analyzed in detail by GC and GC/MS. Multivariate statistical analysis, performed using the in vitro microbiological/toxicological assays and compositional data, revealed that the major components of the essential oils were probably not the main carriers of the activities observed. A formulation of 'designer' mouthwashes is proposed based on the selective action of certain essential oils towards specific bacterial isolates (e. g., Citrus bergamia vs. Parvimonas micra), and non-toxicity to gingival cells at antimicrobially active concentrations.

Anti-Biofouling Coatings on the Tooth Surface and Hydroxyapatite

Dental plaque is one type of biofouling on the tooth surface that consists of a diverse population of microorganisms and extracellular matrix and causes oral diseases and even systematic diseases. Numerous studies have focused on preventing bacteria and proteins on tooth surfaces, especially with anti-biofouling coatings. Anti-biofouling coatings can be stable and sustainable over the long term on the tooth surface in the complex oral environment. In this review, numerous anti-biofouling coatings on the tooth surface and hydroxyapatite (as the main component of dental hard tissue) were summarized based on their mechanisms, which include three major strategies: antiprotein and antibacterial adhesion through chemical modification, contact killing through the modification of antimicrobial agents, and antibacterial agent release. The first strategy of coatings can resist the adsorption of proteins and bacteria. However, these coatings use passive strategies and cannot kill bacteria. The second strategy can interact with the cell membrane of bacteria to cause bacterial death. Due to the possibility of delivering a high antibacterial agent concentration locally, the third strategy is recommended and will be the trend of local drug use in dentistry in the future.

Synthesis of multifunctional chlorhexidine-doped thin films for titanium-based implant materials

Our goal was to create bio-functional chlorhexidine (CHX)-doped thin films on commercially pure titanium (cpTi) discs using the glow discharge plasma approach. Different plasma deposition times (50, 35 and 20 min) were used to create bio-functional surfaces based on silicon films with CHX that were compared to the control groups [no CHX and bulk cpTi surface (machined)]. Physico-chemical and biological characterizations included: 1. Morphology, roughness, elemental chemical composition, film thickness, contact angle and surface free energy; 2. CHX-release rate; 3. Antibacterial effect on Streptococcus sanguinis biofilms at 24, 48 and 72 h; 4. Cytotoxicity and metabolic activity using fibroblasts cell culture (NIH-F3T3 cells) at 1, 2, 3 and 4 days; 5. Protein expression by NIH-F3T3 cells at 1, 2, 3 and 4 days; and 6. Co-culture assay of fibroblasts cells and S. sanguinis to assess live and dead cells on the confocal laser scanning microscopy, mitochondrial activity (XTT), membrane leakage (LDH release), and metabolic activity (WST-1 assay) at 1, 2 and 3 days of co-incubation. Data analysis showed that silicon films, with or without CHX coated cpTi discs, increased surface wettability and free energy (p < 0.05) without affecting surface roughness. CHX release was maintained over a 22-day period and resulted in a significant inhibition of biofilm growth (p < 0.05) at 48 and 72 h of biofilm formation for 50 min and 20 min of plasma deposition time groups, respectively. In general, CHX treatment did not significantly affect NIH-F3T3 cell viability (p > 0.05), whereas cell metabolism (MTT assay) was affected by CHX, with the 35 min of plasma deposition time group displaying the lowest values as compared to bulk cpTi (p < 0.05). Moreover, data analysis showed that films, with or without CHX, significantly affected the expression profile of inflammatory cytokines, including IL-4, IL-6, IL-17, IFN-y and TNF-α by NIH-F3T3 cells (p < 0.05). Co-culture demonstrated that CHX-doped film did not affect the metabolic activity, cytotoxicity and viability of fibroblasts cells (p > 0.05). Altogether, the findings of the current study support the conclusion that silicon films added with CHX can be successfully created on titanium discs and have the potential to affect bacterial growth and inflammatory markers without affecting cell viability/proliferation rates.

Mouthwash Effects on LGG-Integrated Experimental Oral Biofilms

In order to investigate the effects of mouthwashes on oral biofilms with probiotics, we compared in biofilms the susceptibility to mouthwashes of probiotic Lactobacillus rhamnosus GG (LGG) and oral pathogens Streptococcus mutans, Streptococcus sanguinis, and Candida albicans. We also evaluated these pathogens’ susceptibility to the mouthwashes and their recovery after mouthwash-rinsing in biofilms with/without LGG. First, 1-day-/3-day-old LGG-integrated multi-species biofilms were exposed for 1 min to mouthwashes containing chlorhexidine, essential oils, or amine fluoride/stannous fluoride. Cells were plate-counted and relative survival rates (RSRs) of LGG and pathogens calculated. Second, 1-day-/3-day-old multispecies biofilms with and without LGG were exposed for 1 min to mouthwashes; cells were plate-counted and the pathogens’ RSRs were calculated. Third, 1-day-old biofilms were treated for 1 min with mouthwashes. Cells were plate-counted immediately and after 2-day cultivation. Recovery rates of pathogens were calculated and compared between biofilms with/without LGG. Live/Dead^® staining served for structural analyses. Our results showed that RSRs of LGG were insignificantly smaller than those of pathogens in both 1-day and 3-day biofilms. No significant differences appeared in pathogens’ RSRs and recovery rates after treatment between biofilms with/without LGG. To conclude, biofilm LGG was susceptible to the mouthwashes; but biofilm LGG altered neither the mouthwash effects on oral pathogens nor affected their recovery.

Characterization of polymicrobial biofilms obtained from saliva or carious lesions in dentin

This study aimed to compare the formation of polymicrobial biofilms using carious dentin or saliva as inoculum for application in in vitro microbiological studies on caries research. For biofilm growth, combined samples of infected dentin or saliva from three donors were used. The biofilms were grown on glass coverslips, under a regimen of intermittent exposure (6 h day^-1) to 1% sucrose for 4 days. Total bacterial loads, as well as specific aciduric bacteria and mutans streptococci loads were quantified and correlated with biofilm acidogenicity and susceptibility to chlorhexidine. The data were evaluated using the Student's-t, Mann Whitney and Kruskal-Wallis tests. The two biofilms showed similar microbial loads (total bacteria, aciduric bacteria and mutans streptococci) on day 4, and high acidogenicity after 48 h and were susceptible to chlorhexidine at different time intervals. In conclusion, both dentin and saliva can be used as an inoculum in in vitro studies of processes related to biofilm formation.

A Novel Vitamin E TPGS-Based Formulation Enhances Chlorhexidine Bioavailability in Corneal Layers

Keratitis is a severe condition characterized by inflammation of the cornea following a local trauma. The most common ocular disease is the bacterial one, which requires an antibiotic treatment. The major limitation of this therapy is the resistance of the antibiotic. For this reason, alternative procedures have been developed and consist of antimicrobial molecules. One of the most used is the chlorhexidine gluconate, which has shown activity versus Gram-positive and Gram-negative bacteria and fungi. In addition to its efficiency, chlorhexidine shows low toxicity levels for mammalian cells and is a low-cost molecule. Despite its multiple benefits, chlorhexidine, if used at concentrations higher than 0.02% (w/w), can cause local eye irritation. Additionally, its poor penetrability through the cornea makes necessary frequent instillation of eye drops for a prolonged time. Due to these limitations, alternative drug delivery strategies are required. Here, we report a novel formulation based on the combination of d-alpha-tocopherol polyethylene glycol 1000 succinate with chlorhexidine, which results in higher accumulation of the drug in human corneas measured by liquid chromatography and strong antimicrobial activity. Moreover, this formulation does not cause any toxic effect on human cells and is well tolerated by rabbit eyes. Therefore this novel formulation represents a good candidate for the treatment of keratitis that overcomes the risk of antibiotic resistance.

Oral biofilms exposure to chlorhexidine results in altered microbial composition and metabolic profile

Oral diseases (e.g., dental caries, periodontitis) are developed when the healthy oral microbiome is imbalanced allowing the increase of pathobiont strains. Common practice to prevent or treat such diseases is the use of antiseptics, like chlorhexidine. However, the impact of these antiseptics on the composition and metabolic activity of the oral microbiome is poorly addressed. Using two types of oral biofilms—a 14-species community (more controllable) and human tongue microbiota (more representative)—the impact of short-term chlorhexidine exposure was explored in-depth. In both models, oral biofilms treated with chlorhexidine exhibited a pattern of inactivation (>3 log units) and fast regrowth to the initial bacterial concentrations. Moreover, the chlorhexidine treatment induced profound shifts in microbiota composition and metabolic activity. In some cases, disease associated traits were increased (such as higher abundance of pathobiont strains or shift in high lactate production). Our results highlight the need for alternative treatments that selectively target the disease-associated bacteria in the biofilm without targeting the commensal microorganisms.

Review on plant antimicrobials: a mechanistic viewpoint

Microbial resistance to classical antibiotics and its rapid progression have raised serious concern in the treatment of infectious diseases. Recently, many studies have been directed towards finding promising solutions to overcome these problems. Phytochemicals have exerted potential antibacterial activities against sensitive and resistant pathogens via different mechanisms of action. In this review, we have summarized the main antibiotic resistance mechanisms of bacteria and also discussed how phytochemicals belonging to different chemical classes could reverse the antibiotic resistance. Next to containing direct antimicrobial activities, some of them have exerted in vitro synergistic effects when being combined with conventional antibiotics. Considering these facts, it could be stated that phytochemicals represent a valuable source of bioactive compounds with potent antimicrobial activities.

Subgingival microbiome of experimental gingivitis: shifts associated with the use of chlorhexidine and N-acetyl cysteine mouthwashes

This study aimed to demonstrate subgingival microbial changes associated with development, prevention, and treatment of experimental gingivitis using chlorhexidine (CHX) and N-acetylcysteine (NAC) mouthwashes. This randomized clinical trial comprised two parts: a 3-week prevention sub-study in which 30 study subjects were equally assigned to either mouthwash or placebo while developing experimental gingivitis; followed by a 2-week treatment sub-study in which 20 subjects with experimental gingivitis were assigned to either mouthwash. Subgingival samples were collected at the beginning and end of each sub-study for microbial profiling with 16S rRNA gene sequencing. As expected, CHX was effective in both preventing and reversing experimental gingivitis; NAC had a modest effect. Gingivitis was associated with enrichment of TM7 HOT-346/349, Tannerella HOT-286, Cardiobacterium valvarum, Campylobacter gracilis, Porphyromonas catoniae, Leptotrichia HOT-219, and Selenomonas spp. At the phylum/genus level, TM7 showed the strongest association. Gingival health was associated with increased abundance of Haemophilus parainfluenzae, Lautropia mirabilis, Rothia spp., Streptococcus spp., and Kingella oralis. CHX demonstrated largely indiscriminate antimicrobial action, resulting in significant drop in biomass and diversity. Our results substantiate the role of specific oral bacterial species in the development of gingivitis. They also indicate that NAC is not a promising mouthwash at the concentration tested.

Potential of chitosan-based carrier for periodontal drug delivery

Periodontal diseases are chronic infectious diseases and are a major oral health burden. With the progress in the understanding of etiology, epidemiology and pathogenesis of periodontal diseases coupled with the understanding of the polymicrobial synergy in the dysbiotic oral microbial flora, several new therapeutic targets have been identified. The strategies to curb bacterial growth and production of factors that gradually destroy the tissue surrounding and supporting the teeth have been the cornerstone for inhibiting periodontitis. Systemic administration of antibiotics for the treatment of periodontitis have shown several drawbacks including: inadequate antibiotic concentration at the site of the periodontal pocket, a rapid decline of the plasma antibiotic concentration to sub-therapeutic levels, the development of microbial resistance due to sub-therapeutic drug levels and peak-plasma antibiotic concentrations which may be associated with various side effects. These obvious disadvantages have evoked an interest in the development of localized drug delivery systems that can provide an effective concentration of antibiotic at the periodontal site for the duration of the treatment with minimal side effects. A targeted sustained release device which could be inserted in the periodontal pocket and prolong the therapeutic levels at the site of action at a much lower dose is the need of the hour. Chitosan, a deacetylated derivative of chitin has attracted considerable attention owing to its special properties including antimicrobial efficacy, biodegradability, biocompatibility and non-toxicity. It also has the propensity to act as hydrating agent and display tissue healing and osteoinducting effect. The aim of this review is to shine a spotlight on the chitosan based devices developed for drug delivery application in the effective treatment of various periodontal disorders. The chitosan based carriers like fibers, films, sponge, microparticles, nanoparticles, gels that have been designed for sustained release of drug into the periodontal pocket are highlighted.

Peptide Mediated Antimicrobial Dental Adhesive System

The most common cause for dental composite failures is secondary caries due to invasive bacterial colonization of the adhesive/dentin (a/d) interface. Innate material weakness often lead to an insufficient seal between the adhesive and dentin. Consequently, bacterial by-products invade the porous a/d interface leading to material degradation and dental caries. Current approaches to achieve antibacterial properties in these materials continue to raise concerns regarding hypersensitivity and antibiotic resistance. Herein, we have developed a multi-faceted, bio-functionalized approach to overcome the vulnerability of such interfaces. An antimicrobial adhesive formulation was designed using a combination of antimicrobial peptide and a ε-polylysine resin system. Effector molecules boasting innate immunity are brought together with a biopolymer offering a two-fold biomimetic design approach. The selection of ε-polylysine was inspired due to its non-toxic nature and common use as food preservative. Biomolecular characterization and functional activity of our engineered dental adhesive formulation were assessed and the combinatorial formulation demonstrated significant antimicrobial activity against Streptococcus mutans. Our antimicrobial peptide-hydrophilic adhesive hybrid system design offers advanced, biofunctional properties at the critical a/d interface.

Peptide Mediated Antimicrobial Dental Adhesive System

The most common cause for dental composite failures is secondary caries due to invasive bacterial colonization of the adhesive/dentin (a/d) interface. Innate material weakness often lead to an insufficient seal between the adhesive and dentin. Consequently, bacterial by-products invade the porous a/d interface leading to material degradation and dental caries. Current approaches to achieve antibacterial properties in these materials continue to raise concerns regarding hypersensitivity and antibiotic resistance. Herein, we have developed a multi-faceted, bio-functionalized approach to overcome the vulnerability of such interfaces. An antimicrobial adhesive formulation was designed using a combination of antimicrobial peptide and a ε-polylysine resin system. Effector molecules boasting innate immunity are brought together with a biopolymer offering a two-fold biomimetic design approach. The selection of ε-polylysine was inspired due to its non-toxic nature and common use as food preservative. Biomolecular characterization and functional activity of our engineered dental adhesive formulation were assessed and the combinatorial formulation demonstrated significant antimicrobial activity against Streptococcus mutans. Our antimicrobial peptide-hydrophilic adhesive hybrid system design offers advanced, biofunctional properties at the critical a/d interface.

Postoperative effects on lower third molars of using mouthwashes with super-oxidized solution versus 0.2% chlorhexidine gel: A randomized double-blind trial

BACKGROUND

The main objective of the present study is to evaluate the effects and possible benefits with regard to the postoperative period of lower third molar extractions, comparing the intraalveolar application of a bioadhesive gel of 0.2% chlorhexidine (CHX) to the use of a mouthwash with a super-oxidized solution, (SOS) Dermacyn® Wound Care (Oculus Innovative Sciences lnc., California, USA).

MATERIAL AND METHODS

A randomized double-blind study was carried out in 20 patients with a split-mouth design, with a total of 40 extractions of symmetrically impacted bilateral lower third molars. Patients were divided into two groups, a control group (C = 20) and an experimental group (D = 20). Any infectious complications, wound healing, plaque accumulation in the stitches, and presence of trismus and inflammation were evaluated using the distance between different facial points, at three, eight, and fifteen days after extraction. Pain, swelling, and amount of analgesics taken were evaluated using the VAS scale throughout the 15 days following extraction. Tolerance to treatment was evaluated using a verbal scale. Results were statistically compared using the Student's t- and chi-squared tests.

RESULTS

No statistically significant differences were found between the two groups with regard to infectious complications, swelling, or wound healing. Use of analgesics and self-reported pain levels were slightly lower in the experimental group than in the control group during days 6 and 7 of the study (p < 0.05). The global treatment tolerance was satisfactory and similar in both groups.

CONCLUSIONS

Both CHX and SOS are effective at improving the postoperative period after extraction of lower third molars.

Comparative Evaluation of Effects of Triphala, Garlic Extracts, and Chlorhexidine Mouthwashes on Salivary Streptococcus mutans Counts and Oral Hygiene Status

Aims and objectives

To determine and compare the effect of triphala, chlorhexidine gluconate, and garlic extract mouthwash on salivary Streptococcus mutans count and the oral hygiene status.

Materials and methods

Sixty children aged 9 to 12 years were randomly allocated into the study groups of triphala mouthwash, chlorhexidine mouthwash, garlic extracts mouth-wash, and distilled water mouthwash. Examination included decayed, missing, and filled teeth (dmft)/decayed, missing, filled surface (dmfs) and DMFT/DMFS, plaque index, and S. mutans count on days 1, 15, and 30.

Results

The results were statistically analyzed using Friedman test, Wilcoxon signed rank, repeated-measures analysis of variance (ANOVA), paired t-test, one-way ANOVA, post hoc Tukey’s honestly significant different (HSD), Kruskal–Wallis test, and Mann-Whitney test; all calculations were done by MEDCALC software 14.0.0 version.

Discussion

Streptococcus mutans count had significant reductions using different mouthwashes at 15 days, but the chlorhexidine group showed significant difference from the remaining three groups. Intergroup comparison for plaque index scores of triphala, chlorhexidine, and garlic groups was similar in preventing plaque build-up during the 15 days of mouthwash use.

Conclusion

All the three mouthwashes containing triphala, chlorhexidine gluconate, and garlic were comparably efficient in reducing the salivary S. mutans count as well as in limiting plaque score; however, chlorhexidine was the most effective in this aspect. In comparison of the two natural ingredients, Triphala is more effective in its antimicrobial effect.

How to cite this article: Padiyar B, Marwah N, Gupta S, Padiyar N. Comparative Evaluation of Effects of Triphala, Garlic Extracts, and Chlorhexidine Mouthwashes on Salivary Streptococcus mutans Counts and Oral Hygiene Status. Int J Clin Pediatr Dent 2018;11(4):299-306.

Comparison of the Effectiveness of Probiotic, Chlorhexidine-based Mouthwashes, and Oil Pulling Therapy on Plaque Accumulation and Gingival Inflammation in 10- to 12-year-old Schoolchildren: A Randomized Controlled Trial

Introduction

The use of a mouthwash augments mechanical removal of plaque by brushing and flossing and helps maintain oral health through its antiplaque and antibacterial chemical properties.

Aim

To evaluate the effectiveness of a probiotic mouthwash, sesame oil pulling therapy, and chlorhexidine-based mouth-wash on plaque accumulation and gingival inflammation in schoolchildren aged 10 to 12 years.

Materials and methods

The randomized controlled trial included 45 healthy schoolchildren aged 10 to 12 years and studying in Government High School, Tiruchengode, Tamil Nadu, India. The participants were randomly divided into three groups, I, II, and III, with 15 children in each group as follows: group I: probiotic mouthwash; group II: chlorhexidine mouthwash; and group III: sesame oil. Baseline scores of plaque index (PI) and modified gingival index (GI) were recorded followed by a full mouth oral prophylaxis. The designated mouth rinses were distributed to the respective groups and they were instructed to rinse once daily. Their parents supervised the children during the use of mouthwash. On the 15th and 30th day, the children were subjected to the same clinical measurements. Children’s acceptance of their plaque control method was assessed using a modified facial image scale.

Results

Intragroup comparisons for both the GI and PI scores were statistically significant (p ≤ 0.001) in all the three groups. Difference in the GI scores between the 15th and 30th day was statistically significant for chlorhexidine group alone (p = 0.024). Intergroup comparisons between the three groups were not statistically significant.

Conclusion

Probiotic mouthwash, chlorhexidine mouthwash, and sesame oil were equally effective in reducing plaque and in improving the gingival status of children. The difference between the gingival scores on the 15th and 30th day was statistically significant in the chlorhexidine group.

How to cite this article: Kandaswamy SK, Sharath A, Priya PRG. Comparison of the Effectiveness of Probiotic, Chlorhexidine-based Mouthwashes, and Oil Pulling Therapy on Plaque Accumulation and Gingival Inflammation in 10- to 12-year-old Schoolchildren: A Randomized Controlled Trial. Int J Clin Pediatr Dent 2018;11(2):66-70.

Soft, adhesive (+) alpha tocopherol phosphate planar bilayers that control oral biofilm growth through a substantive antimicrobial effect

'Soft' nanomaterials have the potential to produce substantive antibiofilm effects. The aim of this study was to understand the oral antimicrobial activity of soft nanomaterials generated from alpha-tocopherol (α-T) and alpha-tocopherol phosphate (α-TP). (+) α-TP formed planar bilayer islands (175 ± 21 nm, -14.9 ± 3.5 mV) in a Trizma® buffer, whereas (+) α-T formed spherical liposomes (563 ± 1 nm, -10.5 ± 0.2 mV). The (+) α-TP bilayers displayed superior Streptococcus oralis biofilm growth retardation, a more substantive action, generated a superior adsorption to hydroxyapatite and showed an enhanced inhibition of multi-species bacterial saliva biofilm growth (38 ± 7μm vs 58 ± 18 μm, P ˂ 0.05) compared to (+) α-T. Atomic force microscopy data indicated that the ability of the 'soft' α-TP nanomaterials to transition into planar bilayer structures upon contact with interfaces facilitated their adhesive properties and substantive antimicrobial effects.

Thymol and carvacrol induce autolysis, stress, growth inhibition and reduce the biofilm formation by Streptococcus mutans

Organic compounds from plants are an attractive alternative to conventional antimicrobial agents. Therefore, two compounds namely M-1 and M-2 were purified from Origanum vulgare L. and were identified as carvacrol and thymol, respectively. Antimicrobial and antibiofilm activities of these compounds along with chlorhexidine digluconate using various assays was determined against dental caries causing bacteria Streptococcus mutans. The IC₅₀ values of carvacrol (M-1) and thymol (M-2) against S. mutans were 65 and 54 µg/ml, respectively. Live and dead staining and the MTT assays reveal that a concentration of 100 µg/ml of these compounds reduced the viability and the metabolic activity of S. mutans by more than 50%. Biofilm formation on the surface of polystyrene plates was significantly reduced by M-1 and M-2 at 100 µg/ml as observed under scanning electron microscope and by colorimetric assay. These results were in agreement with RT-PCR studies. Wherein exposure to 25 µg/ml of M-1 and M-2 showed a 2.2 and 2.4-fold increase in Autolysin gene (AtlE) expression level, respectively. While an increase of 1.3 and 1.4 fold was observed in the super oxide dismutase gene (sodA) activity with the same concentrations of M-1 and M-2, respectively. An increase in the ymcA gene and a decrease in the gtfB gene expression levels was observed following the treatment with M-1 and M-2. These results strongly suggest that carvacrol and thymol isolated from O. vulgare L. exhibit good bactericidal and antibiofilm activity against S. mutans and can be used as a green alternative to control dental caries.

Optimization of Adhesive Pastes for Dental Caries Prevention

Dental caries prevention products available on the market contain only remineralizing agents or antibacterial agents. This study aimed to develop adhesive pastes containing calcium phosphate and α-mangostin for dental caries prevention using the optimization technique. Calcium phosphate was used as a remineralizing agent, and extracted α-mangostin was used as an antibacterial agent. The effect of the independent variables, which were fumed silica, Eudragit^® EPO, polyethylene glycol, and ethyl alcohol, on the responses was investigated. The drying time, erosion rate, calcium release rate, and α-mangostin release rate were established as the measured responses. An equation and a model of the relationship were constructed. An optimal formulation was obtained, and its effect on dental caries prevention was investigated using the pH-cycling model. The quadratic equation revealed that the drying time, calcium release rate, and α-mangostin release rate tended to decrease when increasing the fumed silica and decreasing other factors. The erosion rate tended to increase when decreasing Eudragit^® EPO and increasing other factors. The observed responses of the optimal adhesive pastes were not significantly different from the predicted responses. This result demonstrated that optimization is an efficient technique in the formulation development of the adhesive pastes. In addition, the optimal adhesive pastes could enhance acid resistance activity to the tooth enamel.

Arginine Exposure Decreases Acidogenesis in Long-Term Oral Biofilm Microcosms

Arginine is used in dental health formulations to help prevent dental cavities. This study assessed the effects of the long-term dosing of laboratory dental plaques with an arginine dentifrice. Data indicate that the addition of arginine dentifrice during sucrose challenge significantly increased plaque pH, thus potentially mitigating cariogenesis. Several functional groups of bacteria associated with tooth decay were significantly decreased in the laboratory plaques during exposure to the arginine dentifrice.

Arginine is an important pH-elevating agent in the oral cavity. It has been incorporated in oral hygiene formulations to mitigate sensitivity and to prevent caries. In this investigation, the effects of sustained arginine dosing of dental plaque microcosms on bacteriological composition and pH were evaluated under controlled conditions. Plaque microcosms were established in constant-depth film fermentors (CDFFs) using salivary inocula and fed continuously with artificial saliva. To simulate resting and cariogenic states, the CDFFs were supplemented with sterile water or 5% sucrose, respectively. Plaques were then dosed twice daily with a dentifrice with 1.5% arginine arginine added (DA) or without arginine (DN). This regimen continued for over 3 weeks, after which fermentors were maintained without dosing. Microcosms were analyzed by differential viable counting, with a pH microelectrode, and by eubacterial DNA profiling. Sucrose dosing was associated with significantly (P < 0.001) decreased pH, significantly (P < 0.05) increased counts of total aerobes, Gram-negative anaerobes, aciduric species, acidogenic species, arginine utilizing species, bifidobacteria, lactobacilli and streptococci, and significant (P < 0.05) changes in DNA profiles. Plaques dosed with DA had a significantly (P < 0.001) higher pH than those dosed with DN, with or without sucrose supplementation. Dosing with DA but not DN significantly (P < 0.05) decreased counts of all functional bacterial groups apart from the total anaerobes in cariogenic plaques, and in resting plaques, dosing with DA significantly (P < 0.05) decreased counts of streptococci, lactobacilli, bifidobacteria, and acidogenic bacteria. In summary, sustained exposure of oral microcosms to arginine in formulation significantly increased plaque pH and significantly reduced the viability of cariogenic bacterial species.

IMPORTANCE Arginine is used in dental health formulations to help prevent dental cavities. This study assessed the effects of the long-term dosing of laboratory dental plaques with an arginine dentifrice. Data indicate that the addition of arginine dentifrice during sucrose challenge significantly increased plaque pH, thus potentially mitigating cariogenesis. Counts of several functional groups of bacteria associated with tooth decay were significantly decreased in the laboratory plaques during exposure to the arginine dentifrice.

In vitro biofilm models to study dental caries: a systematic review

The aim of this systematic review is to characterize and discuss key methodological aspects of in vitro biofilm models for caries-related research and to verify the reproducibility and dose-response of models considering the response to anti-caries and/or antimicrobial substances. Inclusion criteria were divided into Part I (PI): an in vitro biofilm model that produces a cariogenic biofilm and/or caries-like lesions and allows pH fluctuations; and Part II (PII): models showing an effect of anti-caries and/or antimicrobial substances. Within PI, 72.9% consisted of dynamic biofilm models, while 27.1% consisted of batch models. Within PII, 75.5% corresponded to dynamic models, whereas 24.5% corresponded to batch models. Respectively, 20.4 and 14.3% of the studies reported dose-response validations and reproducibility, and 32.7% were classified as having a high risk of bias. Several in vitro biofilm models are available for caries-related research; however, most models lack validation by dose-response and reproducibility experiments for each proposed protocol.

In Vitro Investigation of the Antimicrobial Effect of Three Bisphosphonates Against Different Bacterial Strains

PURPOSE

Since the first descriptions of medication-related osteonecrosis of the jaw (MRONJ) in 2003, the pathogenesis has remained unanswered. Recent histomorphometric studies have found several microorganisms, including Actinomyces, Bacillus, Fusobacterium, Staphylococcus, Streptococcus, Selenomonas, Treponema, and Candida albicans in necrotic bone. Polymerase chain reaction studies have recently confirmed the occurrence of 48 genera. Only a few studies have examined the antimicrobial effect of bisphosphonates (BPs). The influence of bacterial growth on the etiology remains unclear. The aim of the present study was the in vitro investigation of the antimicrobial effect of 3 BPs against different bacterial strains.

MATERIALS AND METHODS

The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 48 strains from 40 species were determined in microdilution assays against pamidronic, ibandronic, and zoledronic acid.

RESULTS

Growth of gram-positive oral microbiota, which account for most microorganisms in MRONJ, was present for 2 of 22 species; 6 of 26 gram-negative species and 9 of 13 anaerobes were inhibited. The MIC values were compared with the BP bone concentrations from previous reports. Of the 48 strains, 9 had an MIC or MBC less than the bone concentrations.

CONCLUSIONS

The results of the present study have demonstrated that BPs have an inhibitory effect on selected bacterial species and might inhibit the growth of some relevant pathogens in osteonecrosis. However, most of the species tested were unaffected at the concentration levels assumed present in the human jawbone. The clinical relevance of these in vitro data will better be clarified with reliable data on the BP concentrations in the human jawbone. The present study has provided a first approach toward the assessment of the interaction of oral bacteria and BPs.

Cytotoxicity and Antimicrobial Activity of Oral Rinses In Vitro

While oral rinses used for cosmetic purposes only do not necessarily have to be antiseptic, antimicrobial activity is required for medical indications, including oral and periodontal surgery. So the question arises—is the antimicrobial activity of oral rinses associated with any destructive changes in cell viability in vitro? To answer this question, we examined twelve oral rinses with respect to their antimicrobial and cytotoxic activity. Antimicrobial activity was screened against five bacterial strains using disc diffusion. Cytotoxicity was determined by mitochondrial reductase activity with primary gingival fibroblasts, L929 cells, and HSC-2 epithelial cells. Phase contrast microscopy and trypan blue staining were then performed to reveal cell morphology. Cells remained vital after exposure to oral rinses that were only used for cosmetic purposes. Moderate cytotoxic effects were observed for oral rinses containing 0.05% chlorhexidine, ethanol, or pegylated hydrogenated castor oil and sodium dodecyl sulfate. Other oral rinses containing 0.2% chlorhexidine and cocamidopropyl betaine exhibited strong cytotoxic and antimicrobial activity. Strong cytotoxic but moderate antimicrobial activity was observed in oral rinses containing cetylpyridinium chloride. The in vitro data show that oral rinses are heterogeneous with respect to their cytotoxic and antimicrobial effects. Based on their respective properties, oral rinses can be selected either to reduce the microbial load or for cosmetic purposes.

New approaches to combat Porphyromonas gingivalis biofilms

In nature, bacteria predominantly reside in structured, surface-attached communities embedded in a self-produced, extracellular matrix. These so-called biofilms play an important role in the development and pathogenesis of many infections, as they are difficult to eradicate due to their resistance to antimicrobials and host defense mechanisms. This review focusses on the biofilm-forming periodontal bacterium Porphyromonas gingivalis. Current knowledge on the virulence mechanisms underlying P. gingivalis biofilm formation is presented. In addition, oral infectious diseases in which P. gingivalis plays a key role are described, and an overview of conventional and new therapies for combating P. gingivalis biofilms is given. More insight into this intriguing pathogen might direct the development of better strategies to combat oral infections.

Variable Effects of Exposure to Formulated Microbicides on Antibiotic Susceptibility in Firmicutes and Proteobacteria

Microbicides are broad-spectrum antimicrobial agents that generally interact with multiple pharmacological targets. While they are widely deployed in disinfectant, antiseptic, and preservative formulations, data relating to their potential to select for microbicide or antibiotic resistance have been generated mainly by testing the compounds in much simpler aqueous solutions. In the current investigation, antibiotic susceptibility was determined for bacteria that had previously exhibited decreased microbicide susceptibility following repeated exposure to microbicides either in formulation with sequestrants and surfactants or in simple aqueous solution. Statistically significant increases in antibiotic susceptibility occurred for 12% of bacteria after exposure to microbicides in formulation and 20% of bacteria after exposure to microbicides in aqueous solutions, while 22% became significantly less susceptible to the antibiotics, regardless of formulation. Of the combinations of a bacterium and an antibiotic for which British Society for Antimicrobial Chemotherapy breakpoints are available, none became resistant. Linear modeling taking into account phylogeny, microbicide, antibiotic, and formulation identified small but significant effects of formulation that varied depending on the bacterium and microbicide. Adaptation to formulated benzalkonium chloride in particular was more likely to increase antibiotic susceptibility than adaptation to the simple aqueous solution. In conclusion, bacterial adaptation through repeated microbicide exposure was associated with both increases and decreases in antibiotic susceptibility. Formulation of the microbicide to which the bacteria had previously adapted had an identifiable effect on antibiotic susceptibility, but it effect was typically small relative to the differences observed among microbicides. Susceptibility changes resulting in resistance were not observed.

IMPORTANCE

The safety of certain microbicide applications has been questioned due to the possibility that microbicide exposure could select for microbicide and antibiotic resistance. Evidence that this may happen is based mainly on in vitro experiments where bacteria have been exposed to microbicides in aqueous solution. Microbicides are, however, normally deployed in products formulated with surfactants, sequestrants, and other compounds. While this may influence the frequency and extent of susceptibility changes, few studies reported in the literature have assessed this. In the current investigation, therefore, we have investigated changes in antibiotic susceptibility in bacteria which exhibited decreased microbicide susceptibility following repeated exposure to microbicides in simple aqueous solutions and in formulation. We report that the microbicide formulation had an identifiable effect on antibiotic susceptibility, but it was typically small relative to the differences observed among microbicides. We did not observe susceptibility changes resulting in resistance.

Inhibition of Streptococcus mutans biofilm formation using extracts from Assam tea compared to green tea

OBJECTIVE

Streptococcus mutans, a gram-positive oral bacterium, has been identified as one of the principal etiological agents of human dental caries. To clarify the nature of the difference anti-biofilm effect against S. mutans between Assam tea from Camellia sinensis var. assamica, partially fermented, and green tea from Camellia sinensis, non-fermented, active agents from the teas were purified.

METHODS

Effects of Assam tea and green tea samples on biofilm were assessed by using the conventional titer plate method and the human saliva-coated hydroxyapatite discs. The purification and identification of inhibitors were performed by using ultrafiltration with centrifugal filter devices and high performance liquid chromatography.

RESULTS

Assam tea has stronger biofilm inhibition activity against S. mutans than green tea. A substance of <10kDa in mass in Assam tea had a high concentration of galloylated catechins and a stronger biofilm inhibiting activity than green tea. In contrast, substances >10kDa in mass from green tea included higher concentrations of polysaccharides composed of galacturonic acid, such as pectin, that enhance biofilm formation.

CONCLUSIONS

The higher concentrations of galloylated catechins in Assam tea may assist in prevention of dental caries, whereas in green tea, this mode of inhibition was likely offset by the presence of pectin. Purification of catechins in partially fermented Assam tea with lower-molecular-weight polysaccharide than pectin may be useful for developing oral care products such as toothpaste and oral care gel pastes.

Antimicrobial properties and dental pulp stem cell cytotoxicity using carboxymethyl cellulose-silver nanoparticles deposited on titanium plates

Objective: To evaluate the antimicrobial properties and dental pulp stem cells (DPSCs) cytotoxicity of synthesized carboxymethyl cellulose-silver nanoparticles impregnated on titanium plates. Material and methods: The antibacterial effect of silver nanoparticles in a carboxymethyl cellulose matrix impregnated on titanium plates (Ti-AgNPs) in three concentrations: 16%, 50% and 100% was determined by adding these to bacterial cultures of Streptococcus mutans and Porphyromonas gingivalis. The Ti-AgNPs cytotoxicity on DPSCs was determined using a fluorimetric cytotoxicity assay with 0.12% chlorhexidine as a positive control. Results: Silver nanoparticles in all concentrations were antimicrobial, with concentrations of 50% and 100% being more cytotoxic with 4% cell viability. Silver nanoparticles 16% had a cell viability of 95%, being less cytotoxic than 0.12% chlorhexidine. Conclusions: Silver nanoparticles are a promising structure because of their antimicrobial properties. These have high cell viability at a concentration of 16%, and are less toxic than chlorhexidine.

Effects of Formulation on Microbicide Potency and Mitigation of the Development of Bacterial Insusceptibility

Risk assessments of the potential for microbicides to select for reduced bacterial susceptibility have been based largely on data generated through the exposure of bacteria to microbicides in aqueous solution. Since microbicides are normally formulated with multiple excipients, we have investigated the effect of formulation on antimicrobial activity and the induction of bacterial insusceptibility. We tested 8 species of bacteria (7 genera) before and after repeated exposure (14 passages), using a previously validated gradient plating system, for their susceptibilities to the microbicides benzalkonium chloride, benzisothiozolinone, chlorhexidine, didecyldimethyl ammonium chloride, DMDM-hydantoin, polyhexamethylene biguanide, thymol, and triclosan in aqueous solution (nonformulated) and in formulation with excipients often deployed in consumer products. Susceptibilities were also assessed following an additional 14 passages without microbicide to determine the stability of any susceptibility changes. MICs and minimum bactericidal concentrations (MBC) were on average 11-fold lower for formulated microbicides than for nonformulated microbicides. After exposure to the antimicrobial compounds, of 72 combinations of microbicide and bacterium there were 19≥4-fold (mean, 8-fold) increases in MIC for nonformulated and 8≥4-fold (mean, 2-fold) increases in MIC for formulated microbicides. Furthermore, there were 20≥4-fold increases in MBC (mean, 8-fold) for nonformulated and 10≥4-fold (mean, 2-fold) increases in MBC for formulated microbicides. Susceptibility decreases fully or partially reverted back to preexposure values for 49% of MICs and 72% of MBCs after further passage. In summary, formulated microbicides exhibited greater antibacterial potency than unformulated actives and susceptibility decreases after repeated exposure were lower in frequency and extent.

Effect of Aloe vera, chlorine dioxide, and chlorhexidine mouth rinses on plaque and gingivitis: A randomized controlled trial

OBJECTIVE

To evaluate the effect of Aloe vera, chlorine dioxide, and chlorhexidine mouth rinses on plaque and gingivitis in orthodontic treatment.

MATERIALS AND METHODS

A randomized single-center, single-blind, parallel group, controlled trial was conducted among 90 subjects undergoing fixed orthodontic treatment. The subjects were randomly divided into one of the three study groups (Aloe vera, chlorhexidine, chlorine dioxide). Plaque and gingivitis were assessed using modified Silness and Loe Plaque Index and Gingival Index at baseline and at follow-up after 15 days. Paired t-test and ANOVA with post hoc Dunnett test were used. A p-value of <0.05 was considered statistically significant.

RESULTS

A total of 85 participants completed the study; among them, 40 were male and 45 were female. There was significant reduction in mean plaque and gingival scores in all the 3 groups at follow-up when compared to baseline. A significantly higher reduction (plaque and gingival scores) was found in chlorhexidine when compared with the Aloe vera group. However, no significant difference was seen between chlorhexidine and chlorine dioxide with respect to mean reduction in plaque and gingival scores.

CONCLUSION

Chlorine dioxide can be a suitable and economical alternative for chlorhexidine. Further long-term studies are recommended for evaluating their effectiveness.

Nonsurgical Management of Phenytoin-induced Gingival Hyperplasia

INTRODUCTION

The aim of this report is to present a severe case of phenytoin (PHT)-induced gingival hyperplasia in a Saudi patient.

MATERIALS AND METHODS

A 12-year-old male epileptic patient, undergoing PHT therapy, was diagnosed clinically with severe gingival hyperplasia. His treatment consisted meticulous oral care and weekly professional prophylaxis. The patient was advised oral folic acid supplementation (0.5 mg/day) and was also recommended 0.2% chlorhexidine gluconate mouthwash twice daily.

RESULTS

There was significant reduction in the hyperplastic tissue within 4 weeks of treatment.

CONCLUSION

It is possible to treat PHT-induced gingival hyperplasia non-surgically with intensive dental care, correct oral hygiene and oral folic acid supplements.

Chlorhexidine-loaded hydroxyapatite microspheres as an antimicrobial delivery system and its effect on in vivo osteo-conductive properties

Hydroxyapatite (HA) has been investigated as a delivery system for antimicrobial and antibacterial agents to simultaneously stimulate bone regeneration and prevent infection. Despite evidence supporting the bactericidal efficiency of these HA carriers, few studies have focused on the effect of this association on bone regeneration. In this work, we evaluated the physico-chemical properties of hydroxyapatite microspheres loaded with chlorhexidine (CHX) at two different concentrations, 0.9 and 9.1 μgCHX/cm2 HA, and characterized their effects on in vitro osteoblast viability and bone regeneration. Ultraviolet-visible spectroscopy, scanning and transmission electron microscopy associated with energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy were used to characterize the association of CHX and HA nanoparticles. The high CHX loading dose induced formation of organic CHX plate-like aggregates on the HA surface, whereas a Langmuir film was formed at the low CHX surface concentration. Quantitative evaluation of murine osteoblast viability parameters, including adhesion, mitochondrial activity and membrane integrity of cells exposed to HA/CHX extracts, revealed a cytotoxic effect for both loading concentrations. Histomorphological analysis upon implantation into the dorsal connective tissues and calvaria of rats for 7 and 42 days showed that the high CHX concentration induced the infiltration of inflammatory cells, resulting in retarded bone growth. Despite a strong decrease in in vitro cell viability, the low CHX loading dose did not impair the biocompatibility and osteoconductivity of HA during bone repair. These results indicate that high antimicrobial doses may activate a strong local inflammatory response and disrupt the long-term osteoconductive properties of CHX-HA delivery systems.

Effect of coconut oil in plaque related gingivitis - A preliminary report

BACKGROUND

Oil pulling or oil swishing therapy is a traditional procedure in which the practitioners rinse or swish oil in their mouth. It is supposed to cure oral and systemic diseases but the evidence is minimal. Oil pulling with sesame oil and sunflower oil was found to reduce plaque related gingivitis. Coconut oil is an easily available edible oil. It is unique because it contains predominantly medium chain fatty acids of which 45-50 percent is lauric acid. Lauric acid has proven anti inflammatory and antimicrobial effects. No studies have been done on the benefits of oil pulling using coconut oil to date. So a pilot study was planned to assess the effect of coconut oil pulling on plaque induced gingivitis.

MATERIALS AND METHODS

The aim of the study was to evaluate the effect of coconut oil pulling/oil swishing on plaque formation and plaque induced gingivitis. A prospective interventional study was carried out. 60 age matched adolescent boys and girls in the age-group of 16-18 years with plaque induced gingivitis were included in the study and oil pulling was included in their oral hygiene routine. The study period was 30 days. Plaque and gingival indices of the subjects were assessed at baseline days 1,7,15 and 30. The data was analyzed using paired t test.

RESULTS

A statistically significant decrease in the plaque and gingival indices was noticed from day 7 and the scores continued to decrease during the period of study.

CONCLUSION

Oil pulling using coconut oil could be an effective adjuvant procedure in decreasing plaque formation and plaque induced gingivitis.