Synthesis and characterization of honey based hybrid dental implants with enhanced antibacterial activity.

Dental implants are commonly used for tooth replacement tools due to their good oral rehabilitation and reconstruction capacities. Dental implants treatment for natural teeth is desired to achieve successful implants treatment with improved osseointegration through promotion of mammalian cell activity and prevention of bacterial activity. Honey is potentially known for its antimicrobial and antibacterial potential, specifically for burns and wound healing. In this study, honey based silver nanoparticles were synthesized using various concentrations of honey. The synthesized HNY-AgNPs, MSN and HNY-AgMSN were characterized for their surface Plasmon resonance using UV spectroscopy, Hydrodynamic diameter using Zetasizer. Morphology using AFM. Furthermore, surface functional groups were characterized using FTIR spectroscopy at 4cm-1 resolutions. The developed hybrid nanoparticles were tested for their anti-bacterial activity at concentration of 3000µg/mL. It was found HNY-AgNPs was active against both bacterial strains i.e, Streptococcus mutans and streptococcus aureus. HNY-AgNPs-MSN hybrid implant demonstrated potential new type of dental implants, which can offer an effective design for the fabrication of advanced dental implants.

Investigation of mechanical properties, remineralization, antibacterial effect, and cellular toxicity of composite orthodontic adhesive combined with silver-containing nanostructured bioactive glass.

BACKGROUND: The formation of white spots, which represent early carious lesions, is a major issue with fixed orthodontics. The addition of remineralizing agents to orthodontic adhesives may prevent the formation of white spots. The aim of this study was to produce a composite orthodontic adhesive combined with nano-bioactive glass-silver (nBG@Ag) for bracket bonding to enamel and to investigate its cytotoxicity, antimicrobial activity, remineralization capability, and bond strength. METHODS: nBG@Ag was synthesized using the sol-gel method, and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy with an attenuated total reflectance attachment (ATR-FTIR). The cytotoxicity test (MTT) and antimicrobial activity of adhesives containing 1%, 3%, and 5% (wt/wt) nBG@Ag were evaluated, and the shear bond strength of the adhesives was measured using a universal testing machine. Remineralization was assessed through microhardness testing with a Vickers microhardness tester and scanning electron microscopy (SEM). Statistical analyses were conducted using the Shapiro-Wilk test, Levene test, one-way ANOVA, Robust-Welch test, Tukey HSD method, and two-way ANOVA. RESULTS: The biocompatibility of the adhesives was found to be high, as confirmed by the lack of significant differences in the cytotoxicity between the sample and control groups. Discs made from composites containing nBG@Ag exhibited a significant reduction in the growth of Streptococcus mutans (p < 0.05), and the antibacterial activity increased with higher percentages of nBG@Ag. The shear bond strength of the adhesives decreased significantly (p < 0.001) after the addition of nanoparticles, but it remained above the recommended value. The addition of nBG@Ag showed improvement in the microhardness of the teeth, although the differences in microhardness between the study groups were not statistically significant. The formation of hydroxyapatite deposits on the tooth surface was confirmed through SEM and energy-dispersive X-ray spectroscopy (EDX). CONCLUSION: Adding nBG@Ag to orthodontic adhesives can be an effective approach to enhance antimicrobial activity and reduce enamel demineralization around the orthodontic brackets, without compromising biocompatibility and bond strength.

Evaluation of the surface characteristics and antibacterial properties of Titanium dioxide nanotube and methacryloyloxyethylphosphorylcholine (MPC) coated orthodontic brackets-a comparative invitro study.

OBJECTIVES: White spot lesions are the most common iatrogenic effect observed during orthodontic treatment. This study aimed to compare the surface characteristics and antibacterial action of uncoated and coated orthodontic brackets. MATERIALS AND METHODS: Sixty commercially available stainless steel brackets were coated with TiO2 nanotubes and methacryloyloxyethylphosphorylcholine. The sample was divided into Group 1: uncoated orthodontic brackets, Group 2: Stainless steel brackets with TiO2 nanotubes coating, Group 3: Stainless steel brackets with methacryloyloxyethylphosphorylcholine coating, and Group 4: Stainless steel brackets with TiO2 nanotubes combined with methacryloyloxyethylphosphorylcholine coating. Surface characterization was assessed using atomic force microscopy and scanning electron microscopy. Streptococcus mutans was selected to test the antibacterial ability of the orthodontic brackets, total bacterial adhesion and bacterial viability were assessed. The brackets were subjected to scanning electron microscopy to detect the presence of biofilm. RESULTS: The surface roughness was the greatest in Group 1 and least in Group 2 followed by Group 4 and Group 3 coated brackets. The optical density values were highest in Group 1 and lowest in Group 4. Comparison of colony counts revealed high counts in Group 1 and low counts in Group 4. A positive correlation between surface roughness and colony counts was obtained, however, was not statistically significant. CONCLUSIONS: The coated orthodontic brackets exhibited less surface roughness than the uncoated orthodontic brackets. Group 4 coated orthodontic brackets showed the best antibacterial properties. CLINICAL RELEVANCE: Coated orthodontic brackets prevent adhesion of streptococcus mutans and reduces plaque accumulation around the brackets thereby preventing formation of white spot lesions during orthodontic treatment.

Antimicrobial efficacy of direct air gas soft jet plasma for the in vitro reduction of oral bacterial biofilms.

The aim of this study was to evaluate the antimicrobial efficacy of an air gas soft jet CAP for its potential use in removing oral biofilms, given that plasma-based technologies have emerged as promising methods in periodontology. Two types of biofilms were developed, one by Streptococcus mutans UA 159 bacterial strain and the other by a complex mixture of saliva microorganisms isolated from a patient with periodontitis. This latter biofilm was characterized via Next Generation Sequencing to determine the main bacterial phyla. The CAP source was applied at a distance of 6 mm for different time points. A statistically significant reduction of both CFU count and XTT was already detected after 60 s of CAP treatment. CLSM analysis supported CAP effectiveness in killing the microorganisms inside the biofilm and in reducing the thickness of the biofilm matrix. Cytotoxicity tests demonstrated the possible use of CAP without important side effects towards human gingival fibroblasts cell line. The current study showed that CAP treatment was able to significantly reduce preformed biofilms developed by both S. mutans and microorganisms isolated by a saliva sample. Further studies should be conducted on biofilms developed by additional saliva donors to support the potential of this innovative strategy to counteract oral pathogens responsible for periodontal diseases.

Antibacterial activities of Miang extracts against selected pathogens and the potential of the tannin-free extracts in the growth inhibition of Streptococcus mutans.

Bacterial pathogens have remained a major public health concern for several decades. This study investigated the antibacterial activities of Miang extracts (at non-neutral and neutral pH) against Bacillus cereus TISTR 747, Escherichia coli ATCC 22595, Salmonella enterica serovar Typhimurium TISTR 292 and Streptococcus mutans DMST 18777. The potential of Polyvinylpolypyrrolidone (PVPP)-precipitated tannin-free Miang extracts in growth-inhibition of the cariogenic Streptococcus mutans DMST 18777 and its biofilms was also evaluated. The tannin-rich fermented extracts had the best bacterial growth inhibition against S. mutans DMST 18777 with an MIC of 0.29 and 0.72 mg/mL for nonfilamentous fungi (NFP) Miang and filamentous-fungi-processed (FFP) Miang respectively. This observed anti-streptococcal activity still remained after PVPP-mediated precipitation of bioactive tannins especially, in NFP and FFP Miang. Characterization of the PVPP-treated extracts using High performance liquid chromatography quadrupole-time of flight-mass spectrometry (HPLC-QToF-MS) analysis, also offered an insight into probable compound classes responsible for the activities. In addition, Crystal violet-staining also showed better IC50 values for NFP Miang (4.30 ± 0.66 mg/mL) and FFP Miang (12.73 ± 0.11 mg/mL) against S. mutans DMST 18777 biofilms in vitro. Homology modeling and molecular docking analysis using HPLC-MS identified ligands in tannin-free Miang supernatants, was performed against modelled S. mutans DMST 18777 sortase A enzyme. The in silico analysis suggested that the inhibition by NFP and FFP Miang might be attributed to the presence of ellagic acid, flavonoid aglycones, and glycosides. Thus, these Miang extracts could be optimized and explored as natural active pharmaceutical ingredients (NAPIs) for applications in oral hygienic products.

Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study.

AIM AND BACKGROUND: This study aimed to explore the potential synergistic interaction of virgin coconut oil (VCO) and virgin olive oil (VOO) mixture against Streptococcus sanguinis, Streptococcus mutans, and Lactobacillus casei in a single and mixture species through the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antiadherence, and antibiofilm activities. MATERIALS AND METHODS: The broth microdilution technique was used to individually determine the MIC of both oils and an oil mixture (in the ratio of 1:1) in a 96-well microtiter plate. As for the MBC, the subcultured method was used. The fractional inhibitory concentration index (ΣFIC) was determined to identify the interaction types between both oils. The oil mixture at its MIC was then tested on its antibiofilm and antiadherence effect. RESULTS: The MIC of the oil mixture against the tested microbiota was 50-100%. The oil mixture was bactericidal at 100% concentration for all the mentioned microbes except S. mutans. The ΣFIC value was 2 to 4, indicating that the VCO and VOO acted additively against the microbiota. Meanwhile, the oil mixture at MIC (50% for S. sanguinis and L. casei; 100% for S. mutans and mixture species) exhibited antiadherence and antibiofilm activity toward the microbiota in mixture species. CONCLUSION: The oil mixture possesses antibacterial, antibiofilm, and antiadherence properties toward the tested microbiota, mainly at 50-100% concentration of oil mixture. There was no synergistic interaction found between VCO and VOO. CLINICAL SIGNIFICANCE: Children and individuals with special care may benefit from using the oil mixture, primarily to regulate the biofilm formation and colonization of the bacteria. Furthermore, the oil mixture is natural and nontoxic compared to chemical-based oral healthcare products. How to cite this article: Ng YM, Sockalingam SNMP, Shafiei Z, et al. Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study. J Contemp Dent Pract 2024;25(3):260-266.

Metabolomics reveals high fructose-1,6-bisphosphate from fluoride-resistant Streptococcus mutans.

BACKGROUND: Fluoride-resistant Streptococcus mutans (S. mutans) strains have developed due to the wide use of fluoride in dental caries prevention. However, the metabolomics of fluoride-resistant S. mutans remains unclear. OBJECTIVE: This study aimed to identify metabolites that discriminate fluoride-resistant from wild-type S. mutans. MATERIALS AND METHODS: Cell supernatants from fluoride-resistant and wild-type S. mutans were collected and analyzed by liquid chromatography-mass spectrometry. Principal components analysis and partial least-squares discriminant analysis were performed for the statistical analysis by variable influence on projection (VIP > 2.0) and p value (Mann-Whitney test, p < 0.05). Metabolites were assessed qualitatively using the Human Metabolome Database version 2.0 ( http://www.hmdb.ca ), or Kyoto Encyclopedia of Genes and Genomes ( http://www.kegg.jp ), and Metaboanalyst 6.0 ( https://www.metaboanalyst.ca ). RESULTS: Fourteen metabolites differed significantly between fluoride-resistant and wild-type strains in the early log phase. Among these metabolites, 5 were identified. There were 32 differential metabolites between the two strains in the stationary phase, 13 of which were identified. The pyrimidine metabolism for S. mutans FR was matched with the metabolic pathway. CONCLUSIONS: The fructose-1,6-bisphosphate concentration increased in fluoride-resistant strains under acidic conditions, suggesting enhanced acidogenicity and acid tolerance. This metabolite may be a promising target for elucidating the cariogenic and fluoride resistant mechanisms of S. mutans.

Examination of cytotoxic and antimicrobial effect of whitening toothpastes: an in vitro study.

OBJECTIVE: Toothpastes are widely used to protect oral and teeth health. This study aims to examine the cytotoxic and antimicrobial effects of whitening toothpastes. METHODS: In this study, extracts were prepared according to ISO 10993-12:2021 standard (0.2 g/mL) using whitening and conventional toothpastes. The prepared extracts were added to human gingival fibroblast cell lines (HGF-1) in different dilutions (1:1, 1:2, 1:4, 1:8, 1:16, and 1:32) and a cytotoxicity test was performed. Antimicrobial analysis of toothpastes was performed on Streptococcus mutans, Staphylococcus aureus, and Candida albicans using the hole-plate diffusion method. Cell viability and microbial analysis data were examined using two-way analysis of variance (ANOVA) and Tukey post-hoc test (p < 0.05). RESULTS: Toothpastes with sodium lauryl sulfate (SLS) in their composition showed statistically more toxic effects (p < 0.05). The activated carbon toothpastes without SLS showed over 90% cell viability after dilution. Although the dilution rate of toothpastes containing SLS increased, cell viability remained below 70%. All toothpastes used in the study showed antimicrobial effects on S. mutans, S. aureus, and C. albicans. Toothpaste containing hydrogen peroxide and SLS produced more antibacterial effects than activated carbon, blue covarine, microparticles, and conventional toothpaste. CONCLUSIONS: SLS-containing toothpastes showed more toxicity on HGF-1 cells. Toothpaste containing hydroxyapatite did not show toxic effects on HGF-1 cells. SLS, sodium lauryl sarcosinate and hydrogen peroxide in toothpastes increase antimicrobial effects.

Chitosan Phytate Nanoparticles: A Synergistic Strategy for Effective Dental Caries Prevention.

Dental caries is a widespread oral disease that poses a significant medical challenge. Traditional caries prevention methods, primarily the application of fluoride, often fall short in effectively destroying biofilms and preventing enamel demineralization, thereby providing limited efficacy in halting the progression of caries over time. To address this issue, we have developed a green and cost-effective synergistic strategy for the prevention of dental caries. By combining natural sodium phytate and chitosan, we have created chitosan-sodium phytate nanoparticles that offer both the antimicrobial properties of chitosan and the enamel demineralization-inhibiting capabilities of sodium phytate. In an ex vivo biofilm model of human teeth, we found that these nanoparticles effectively prevent biofilm buildup and acid damage to the mineralized tissue. Additionally, topical treatment of dental caries in rodent models has shown that these nanoparticles effectively suppress disease progression without negatively impacting oral microbiota diversity or causing harm to the gingival-mucosal tissues, unlike traditional prevention methods.

Efficacy of a mouthwash containing ε-poly-L-lysine, funme peptides and domiphen in reducing halitosis and supragingival plaque: a randomized clinical trial.

OBJECTIVE: To evaluate the antibacterial effectiveness of a combination of ε-poly-L-lysine (ε-PL), funme peptide (FP) as well as domiphen against oral pathogens, and assess the efficacy of a BOP® mouthwash supplemented with this combination in reducing halitosis and supragingival plaque in a clinical trial. MATERIALS AND METHODS: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the compound against Fusobacterium nucleatum, Porphyromonas gingivalis, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans were determined by the gradient dilution method. Subsequently, the CCK-8 assay was used to detect the toxicity of mouthwash on human gingival fibroblastst, and the effectiveness in reducing halitosis and supragingival plaque of the mouthwash supplemented with the combination was analyzed by a randomized, double-blind, parallel-controlled clinical trial. RESULTS: The combination exhibited significant inhibitory effects on tested oral pathogens with the MIC < 1.56% (v/v) and the MBC < 3.13% (v/v), and the mouthwash containing this combination did not inhibit the viability of human gingival fibroblasts at the test concentrations. The clinical trial showed that the test group displayed notably lower volatile sulfur compounds (VSCs) at 0, 10, 24 h, and 7 d post-mouthwash (P < 0.05), compared with the baseline. After 7 days, the VSC levels of the and control groups were reduced by 50.27% and 32.12%, respectively, and notably cutting severe halitosis by 57.03% in the test group. Additionally, the Plaque Index (PLI) of the test and control group decreased by 54.55% and 8.38%, respectively, and there was a significant difference in PLI between the two groups after 7 days (P < 0.01). CONCLUSIONS: The combination of ε-PL, FP and domiphen demonstrated potent inhibitory and bactericidal effects against the tested oral pathogens, and the newly formulated mouthwash added with the combination exhibited anti-dental plaque and anti-halitosis properties in a clinical trial and was safe. TRIAL REGISTRATION: The randomized controlled clinical trial was registered on Chinese Clinical Trial Registry (No. ChiCTR2300073816, Date: 21/07/2023).

Antimicrobial activity of cleanser tablets against S. mutans and C. Albicans on different denture base materials.

BACKGROUND: In this study, the antimicrobial activity of three different cleanser tablets on S. mutans and C. albicans adhesion to PMMA, polyamide and 3D printed resin was investigated. METHODS: 40 samples were prepared for PMMA (SR Triplex Hot), polyamide (Deflex) and 3D printed resin (PowerResins Denture) materials and divided into four subgroups for cleansers (Aktident™, Protefix™, Corega™ tablets and distilled water) (n = 5). After the surface preparations were completed, the samples were immersed separately in tubes containing the prepared microorganism suspension and incubated at 37˚C for 24 h. After the incubation, the samples were kept in the cleanser solutions. The samples were then transferred to sterile saline tubes. All the tubes were vortexed and 10 µl was taken from each of them. Sheep blood agar was inoculated for colony counting. The inoculated plates were incubated for 48 h for S. mutans and 24 h for C. albicans. After incubation, colonies observed on all plates were counted. Statistical analyses were done with three-way ANOVA and Tukey's multiple comparison test. RESULTS: Polyamide material registered the highest colony count of S. mutans, whereas PMMA registered the lowest. Significant differences in S. mutans adherence (p = 0.002) were found between the three denture base materials, but no such difference in C. albicans adherence (p = 0.221) was identified between the specimens. All three cleanser tablets eliminated 98% of S. mutans from all the material groups. In all these groups, as well, the antifungal effect of Corega™ on C. albicans was significantly higher than those of the other two cleanser tablets. CONCLUSIONS: According to the study's results, it may be better to pay attention to surface smoothness when using polyamide material to prevent microorganism retention. Cleanser tablets are clinically recommended to help maintain hygiene in removable denture users, especially Corega tablets that are more effective on C. albicans.

Antibacterial Activity of Epigallocatechin-3-gallate (EGCG) Loaded Lipid-chitosan Hybrid Nanoparticle against Planktonic Microorganisms.

Epigallocatechin-3-gallate (EGCG), a polyphenol derived from Green Tea, is one of the sources of natural bioactive compounds which are currently being developed as medicinal ingredients. Besides other biological activities, this natural compound exhibits anti-cariogenic effects. However, EGCG has low physical-chemical stability and poor bioavailability. Thus, the purpose of this study was to develop and characterize lipid-chitosan hybrid nanoparticle with EGCG and to evaluate its in vitro activity against cariogenic planktonic microorganisms. Lipid-chitosan hybrid nanoparticle (LCHNP-EGCG) were prepared by emulsion and sonication method in one step and characterized according to diameter, polydispersity index (PdI), zeta potential (ZP), encapsulation efficiency (EE), mucoadhesion capacity and morphology. Strains of Streptococcus mutans, Streptococcus sobrinus and Lactobacillus casei were treated with LCHNP- EGCG, and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were evaluated. LCHNP-EGCG exhibited a size of 217.3 ± 5.1 nm with a low polydispersity index (0.17) and positive zeta potential indicating the presence of chitosan on the lipid nanoparticle surface (+33.7 mV). The LCHNP-EGCG showed a spherical morphology, high stability and a mucoadhesive property due to the presence of chitosan coating. In addition, the EGCG encapsulation efficiency was 96%. A reduction of almost 15-fold in the MIC and MBC against the strains was observed when EGCG was encapsulated in LCHNP, indicating the potential of EGCG encapsulation in lipid-polymer hybrid nanoparticles. Taking the results together, the LCHNP-EGCG could be an interesting system to use in dental care due to their nanometric size, mucoadhesive properties high antibacterial activity against relevant planktonic microorganisms.

Effectiveness of experimental dentifrices based on essential oils on biofilm on complete dentures: an in vitro study.

Specific products containing natural resources can contribute to the innovation of complete denture hygiene. OBJECTIVE: To conduct an in vitro evaluation of experimental dentifrices containing essential oils of Bowdichia virgilioides Kunth (BvK), Copaifera officinalis (Co), Eucalyptus citriodora (Ec), Melaleuca alternifolia (Ma) and Pinus strobus (Ps) at 1%. METHODOLOGY: The variables evaluated were organoleptic and physicochemical characteristics, abrasiveness (mechanical brushing machine) simulating 2.5 years, and microbial load (Colony Forming Units - CFU/mL), metabolic activity (XTT assay) and cell viability (Live/Dead® BacLight™ kit) of the multispecies biofilm (Streptococcus mutans: Sm, Staphylococcus aureus: Sa, Candida albicans: Ca and Candida glabrata: Cg). Specimens of heat-polymerized acrylic resins (n=256) (n=96 specimens for abrasiveness, n=72 for microbial load count, n=72 for biofilm metabolic activity, n=16 for cell viability and total biofilm quantification) with formed biofilm were divided into eight groups for manual brushing (20 seconds) with a dental brush and distilled water (NC: negative control), Trihydral (PC: positive control), placebo (Pl), BvK, Co, Ec, Ma or Ps. After brushing, the specimens were washed with PBS and immersed in Letheen Broth medium, and the suspension was sown in solid specific medium. The organoleptic characteristics were presented by descriptive analysis. The values of density, pH, consistency and viscosity were presented in a table. The data were analyzed with the Wald test in a generalized linear model, followed by the Kruskal-Wallis test, Dunn's test (mass change) and the Bonferroni test (UFC and XTT). The Wald test in Generalized Estimating Equations and the Bonferroni test were used to analyze cell viability. RESULTS: All dentifrices showed stable organoleptic characteristics and adequate physicochemical properties. CN, Ec, Ps, Pl and PC showed low abrasiveness. There was a significant difference between the groups (p<0.001) for microbial load, metabolic activity and biofilm viability. CONCLUSIONS: It was concluded that the BvK, Ec and Ps dentifrices are useful for cleaning complete dentures, as they have antimicrobial activity against biofilm. The dentifrices containing Bowdichia virgilioides Kunth showed medium abrasiveness and should be used with caution.

Poly-3-hydroxybutyrate-silver nanoparticles membranes as advanced antibiofilm strategies for combatting peri-implantitis.

Dental implant success is threatened by peri-implantitis, an inflammation leading to implant failure. Conventional treatments struggle with the intricate microbial and host factors involved. Antibacterial membranes, acting as barriers and delivering antimicrobials, may offer a promising solution. Thus, this study highlights the potential of developing antibacterial membranes of poly-3-hydroxybutyrate and silver nanoparticles (Ag Nps) to address peri-implantitis challenges, discussing design and efficacy against potential pathogens. Electrospun membranes composed of PHB microfibers and Ag Nps were synthesized in a blend of DMF/chloroform at three different concentrations. Various studies were conducted on the characterization and antimicrobial activity of the membranes. The synthesized Ag Nps ranged from 4 to 8 nm in size. Furthermore, Young's modulus decreased, reducing from 13.308 MPa in PHB membranes without Ag Nps to 0.983 MPa in PHB membranes containing higher concentrations of Ag Nps. This demonstrates that adding Ag Nps results in a less stiff membrane. An increase in elongation at break was noted with the rise in Ag Nps concentration, from 23.597 % in PHB membranes to 60.136 % in PHB membranes loaded with Ag Nps. The antibiotic and antibiofilm activity of the membranes were evaluated against Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus mutans, and Candida albicans. The results indicated that all PHB membranes containing Ag Nps exhibited potent antibacterial activity by inhibiting the growth of biofilms and planktonic bacteria. However, inhibition of C. albicans occurred only with the PHB-Ag Nps C membrane. These findings emphasize the versatility and potential of Ag Nps-incorporated membranes as a multifunctional approach for preventing and addressing microbial infections associated with peri-implantitis. The combination of antibacterial and antibiofilm properties in these membranes holds promise for improving the management and treatment of peri-implantitis-related complications.

Antibacterial effect and biocompatibility of silver nanoparticle-coated bone allograft substitutes.

Osteoinduction, and/or osteoconduction, and antibacterial characteristics are prerequisites for achieving successful bone grafting. This study aimed to coat bone allografts with silver nanoparticles and assess their antibacterial activity and biocompatibility compared to uncoated bone allografts. In this study, the bone allografts were coated with varying concentrations of silver nanoparticles (5 mg/l, 10 mg/l, and 50 mg/l) through a simple adsorption technique. Subsequently, the coated samples underwent characterization using SEM, FTIR, EDS, and XRD. The Minimal Inhibitory Concentration (MIC) of the silver nanoparticles was determined against Staphylococcus aureus and Streptococcus mutans. Bacterial growth inhibition was evaluated by measuring turbidity and performing a disk diffusion test. Moreover, qualitative investigation of biofilm formation on the coated bone allograft was conducted using SEM. Following this, MG-63 cell lines, resembling osteoblasts, were cultured on the bone allografts coated with 5 mg/l of silver nanoparticles, as well as on uncoated bone allografts, to assess biocompatibility. The MIC results demonstrated that silver nanoparticles exhibited antimicrobial effects on both microorganisms, inhibiting the growth of isolates at concentrations of 0.78 mg/L for Staphylococcus aureus and 0.39 mg/L for Streptococcus mutans. The bone allografts coated with varying concentrations of silver nanoparticles exhibited significant antibacterial activity against the tested bacteria, completely eradicating bacterial growth and preventing biofilm formation. The osteoblast-like MG-63 cells thrived on the bone allografts coated with 5 mg/l of silver nanoparticles, displaying no significant differences compared to both the uncoated bone allografts and the control group.  Within the limit of this study, it can be concluded that silver nanoparticles have a positive role in controlling graft infection. In addition, simple adsorption technique showed an effective method of coating without overwhelming the healing of the graft.

Measurement and analysis of microbial fluoride resistance in dental biofilm models.

The interactions between communities of microorganisms inhabiting the dental biofilm is a major determinant of oral health. These biofilms are periodically exposed to high concentrations of fluoride, which is present in almost all oral healthcare products. The microbes resist fluoride through the action of membrane export proteins. This chapter describes the culture, growth and harvest conditions of model three-species dental biofilm comprised of cariogenic pathogens Streptococcus mutans and Candida albicans and the commensal bacterium Streptococcus gordonii. In order to examine the role of fluoride export by S. mutans in model biofilms, procedures for generating a strain of S. mutans with a genetic knockout of the fluoride exporter are described. We present a case study examining the effects of this mutant strain on the biofilm mass, acid production and mineral dissolution under exposure to low levels of fluoride. These general approaches can be applied to study the effects of any gene of interest in physiologically realistic multispecies oral biofilms.

The discovery of an anti-inflammatory monoterpenoid, neoroseoside from the Zea mays.

A new monoterpenoid, neoroseoside (1), along with two previously reported compounds, 2″-O-α-l-rhamnosyl-6-C-fucosylluteolin (2) and farobin A (3) were isolated from the Zea mays. The structure of compound 1 was determined through the analysis spectroscopic data, including mass spectrometry (MS), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) data. The absolute configurations of 1 were deduced from the comparing the values of optical rotations and from the interpretation of electronic circular dichroism (ECD) spectra. Compounds 2 and 3 displayed moderate antibacterial activity against Streptococcus mutans ATCC 25175 (inhibition rates 24 % and 28 %, respectively) and Streptococcus sobrinus ATCC 33478 (inhibition rate of 26 %), at a concentration of 100 µg/mL, whereas compound 1 did not have any significant antibacterial activities. The compounds 1-3 also showed anti-inflammatory activity on cytokine IL-6 and TNF-α.

Characterizations of biogenic selenium nanoparticles and their anti-biofilm potential against Streptococcus mutans ATCC 25175.

INTRODUCTION: S. mutans has been identified as the primary pathogenic bacterium in biofilm-mediated dental caries. The biogenic selenium nanoparticles (SeNPs) produced by L. plantarum KNF-5 were used in this study against S. mutans ATCC 25175. OBJECTIVES: The aims of this study were: (1) the biosynthesis of SeNPs by L. plantarum KNF-5, (2) the characterization of SeNPs, (3) the investigation of the inhibitory effect of biogenic SeNPs against S. mutans ATCC 25175, and (4) the determination of the anti-biofilm potential of SeNPS against S. mutans ATCC 25175. METHODOLOGY: 3 mL of the culture was added to 100 mL of MRS medium and incubated. After 4 h, Na2SeO3 solution (concentration 100 µg/mL) was added and incubated at 37 °C for 36 h. The color of the culture solution changed from brownish-yellow to reddish, indicating the formation of SeNPs. The characterization of SeNPs was confirmed by UV-Vis spectrophotometry, FTIR, SEM-EDS and a particle size analyzer. The antibacterial activity was determined by the disk diffusion method, the MIC by the micro-double dilution method, and the biofilm inhibitory potential by the crystal violet method and the MTT assay. The effect of SeNPs on S. mutans ATCC 25175 was determined using SEM and CLSM spectrometry techniques. The sulfate-anthrone method was used to analyze the effect of SeNPs on insoluble extracellular polysaccharides. The expression of genes in S. mutans ATCC 25175 was analyzed by real-time quantitative polymerase chain reaction (RT-qPCR). PREPARATION OF NANOPARTICLES: SeNPs produced by probiotic bacteria are considered a safe method. In this study, L. plantarum KNF-5 (probiotic strain) was used for the production of SeNPs. RESULTS: The biogenic SeNPs were spherical and coated with proteins and polysaccharides and had a diameter of about 270 nm. The MIC of the SeNPs against S. mutans ATCC 25175 was 3.125 mg/mL. Biofilm growth was also significantly suppressed at this concentration. The expression of genes responsible for biofilm formation (GtfB, GtfC, BrpA and GbpB,) was reduced when S. mutans ATCC 25175 was treated with SeNPs. CONCLUSION: It was concluded that the biogenic SeNPs produced by L. plantarum KNF-5 was highly effective to inhibit the growth of S. mutans ATCC 25175. NOVELTY STATEMENT: The application of biogenic SeNPs, a natural anti-biofilm agent against S. mutans ATCC 25175. In the future, this study will provide a new option for the prevention and treatment of dental caries.

Tetracyclic homoisoflavanoid (+)-brazilin: a natural product inhibits c-di-AMP-producing enzyme and Streptococcus mutans biofilms.

The tenacious biofilms formed by Streptococcus mutans are resistant to conventional antibiotics and current treatments. There is a growing need for novel therapeutics that selectively inhibit S. mutans biofilms while preserving the normal oral microenvironment. Previous studies have shown that increased levels of cyclic di-AMP, an important secondary messenger synthesized by diadenylate cyclase (DAC), favored biofilm formation in S. mutans. Thus, targeting S. mutans DAC is a novel strategy to inhibit S. mutans biofilms. We screened a small NCI library of natural products using a fluorescence detection assay. (+)-Brazilin, a tetracyclic homoisoflavanoid found in the heartwood of Caesalpinia sappan, was identified as one of the 11 "hits," with the greatest reduction (>99%) in fluorescence at 100 µM. The smDAC inhibitory profiles of the 11 "hits" established by a quantitative high-performance liquid chromatography assay revealed that (+)-brazilin had the most enzymatic inhibitory activity (87% at 100 µM) and was further studied to determine its half maximal inhibitory concentration (IC50 = 25.1 ± 0.98 µM). (+)-Brazilin non-competitively inhibits smDAC's enzymatic activity (Ki = 140.0 ± 27.13 µM), as determined by a steady-state Michaelis-Menten kinetics assay. In addition, (+)-brazilin's binding profile with smDAC (Kd = 11.87 µM) was illustrated by a tyrosine intrinsic fluorescence quenching assay. Furthermore, at low micromolar concentrations, (+)-brazilin selectively inhibited the biofilm of S. mutans (IC50 = 21.0 ± 0.60 µM) and other oral bacteria. S. mutans biofilms were inhibited by a factor of 105 in colony-forming units when treated with 50 µM (+)-brazilin. In addition, a significant dose-dependent reduction in extracellular DNA and glucan levels was evident by fluorescence microscopy imaging of S. mutans biofilms exposed to different concentrations of (+)-brazilin. Furthermore, colonization of S. mutans on a representative model of enamel using suspended hydroxyapatite discs showed a >90% reduction with 50 µM (+)-brazilin. In summary, we have identified a drug-like natural product inhibitor of S. mutans biofilm that not only binds to smDAC but can also inhibit the function of smDAC. (+)-Brazilin could be a good candidate for further development as a potent therapeutic for the prevention and treatment of dental caries.IMPORTANCEThis study represents a significant advancement in our understanding of potential therapeutic options for combating cariogenic biofilms produced by Streptococcus mutans. The research delves into the use of (+)-brazilin, a natural product, as a potent inhibitor of Streptococcus mutans' diadenylate cyclase (smDAC), an enzyme crucial in the formation of biofilms. The study establishes (+)-brazilin as a non-competitive inhibitor of smDAC while providing initial insights into its binding mechanism. What makes this finding even more promising is that (+)-brazilin does not limit its inhibitory effects to S. mutans alone. Instead, it demonstrates efficacy in hindering biofilms in other oral bacteria as well. The broader spectrum of anti-biofilm activity suggests that (+)-brazilin could potentially serve as a versatile tool in a natural product-based treatment for combating a range of conditions caused by resilient biofilms.

Formulation of arginine-loaded mesoporous silica nanoparticles (Arg@MSNs) modified orthodontic adhesive.

OBJECTIVES: The objective of this study was to synthesize arginine loaded mesoporous silica nanoparticles (Arg@MSNs), develop a novel orthodontic adhesive using Arg@MSNs as modifiers, and investigate the adhesive performance, antibacterial activity, and biocompatibility. METHODS: Arg@MSNs were synthesized by immobilizing arginine into MSNs and characterized using transmission electron microscope (TEM), dynamic light scattering (DLS), and Fourier Transform Infrared Spectrometer (FT-IR). Arg@MSNs were incorporated into Transbond XT adhesive with different mass fraction to form functional adhesives. The degree of conversion (DC), arginine release behavior, adhesive performance, antibacterial activity against Streptococcus mutans biofilm, and cytotoxicity were comprehensively evaluated. RESULTS: TEM, DLS, and FT-IR characterizations confirmed the successful preparation of Arg@MSNs. The incorporation of Arg@MSNs did not significantly affect DC and exhibited clinically acceptable bonding strength. Compared to the commercial control, the Arg@MSNs modified adhesives greatly suppressed the metabolic activity and polysaccharide production while increased the biofilm pH values. The cell counting kit (CCK)-8 test indicated no cytotoxicity. CONCLUSIONS: The novel orthodontic adhesive containing Arg@MSNs exhibited significantly enhanced antibacterial activities and inhibitory effects on acid production compared to the commercial adhesive without compromising their bonding strength or biocompatibility. CLINICAL SIGNIFICANCE: The novel orthodontic adhesive containing Arg@MSNs exhibits potential clinical benefits in preventing demineralization of enamel surfaces around or beneath orthodontic brackets due to its enhanced antibacterial activities and acid-producing inhibitory effects.