Explore the vast range of titles available.

Background Silver diamine fluoride (SDF) is a simple and non-invasive agent used to arrest early childhood caries (ECC). This study aimed to investigate potential changes to the oral microbiome in children with ECC who were treated with SDF and sodium fluoride (NaF) varnish at three different frequency regimens. Methods Forty-five children ( n  = 15 per group) with ECC were recruited from community-based dental clinics in Winnipeg, Canada into an open-label, parallel-group, randomized clinical trial testing three different treatment frequency regimens of SDF. A total of 195 carious lesions were treated with two applications of 38% SDF and 5% NaF varnish (and assessed over three study visits one month, four months, or six months apart. Dental plaque samples were collected at each visit. Sequencing of the V4-16 S rRNA and ITS1 rRNA genes were used to study the supragingival plaque microbiome. Results Microbial diversity analyses showed no significant differences in the overall microbiome after SDF treatment. However, significant changes in the abundance of specific bacteria and fungi, particularly Lactobacillus spp., Bifidobacterium spp., and Candida spp., were observed after treatment. Furthermore, overabundance of Streptococcus mutans and Candida dubliniensis at baseline was observed in children who had at least one caries lesion not arrested after one SDF application, compared to those who had 100% arrest rates. The overall arrest rates for treated carious lesions were 75.9% at the second visit and 92.8% at the third visit. Arrest rates were higher for all lesions after two applications of SDF with NaF varnish, and applications one month and four months apart had higher arrest rates (95.9% and 98.5%) than six months (81.1%) apart. Conclusions Applications of SDF with NaF varnish were an effective modality for arresting ECC, with higher arrest rates after two SDF applications. No loss of diversity but changes in the abundance of specific bacteria and fungi were observed after SDF treatment. Trial registration ClinicalTrials.gove NCT04054635 (first registered 13/08/2019).

The aim of the study was to examine the mean mineral density (MD) change in early proximal enamel caries lesions after applying silver diamine fluoride (SDF) using digital subtraction radiographic analysis at 6 and 12 months. A split-mouth, triple-blind, randomized controlled trial was conducted with thirty healthy participants aged 13–30 years old. Two active non-cavitated proximal caries lesions in different quadrants of each participant were randomly sampled and allocated to a test (38% SDF) and a control group (deionized water). Digital radiographs at baseline, 6 and 12 months were taken, and digital subtraction radiographic analysis was performed. The SDF group demonstrated a significantly higher mean MD on subtraction radiographs compared with the control group, after adjusting for baseline lesion depth and time, and for clustering within participants over time. The adjusted mean difference was 1.0 [95% CI 0.2, 1.9]. Therefore, applying SDF at baseline and 6 months resulted in significant remineralization compared with the control group over the 12-month period. These findings suggested that applying SDF can serve as an effective alternative treatment option for remineralizing early caries lesions on proximal surfaces.

The antimicrobial impact of biogenic-synthesized silver-based nanoparticles has been the focus of increasing interest. As the antimicrobial activity of nanoparticles is highly dependent on their size and surface, the complete and adequate characterization of the nanoparticle is important. This review discusses the characterization and antimicrobial activity of biogenic synthesized silver nanoparticles and silver chloride nanoparticles. By revising the literature, there is confusion in the characterization of these two silver-based nanoparticles, which consequently affects the conclusion regarding to their antimicrobial activities. This review critically analyzes recent publications on the synthesis of biogenic silver nanoparticles and silver chloride nanoparticles by attempting to correlate the characterization of the nanoparticles with their antimicrobial activity. It was difficult to correlate the size of biogenic nanoparticles with their antimicrobial activity, since different techniques are employed for the characterization. Biogenic synthesized silver-based nanoparticles are not completely characterized, particularly the nature of capped proteins covering the nanomaterials. Moreover, the antimicrobial activity of theses nanoparticles is assayed by using different protocols and strains, which difficult the comparison among the published papers. It is important to select some bacteria as standards, by following international foundations (Pharmaceutical Microbiology Manual) and use the minimal inhibitory concentration by broth microdilution assays from Clinical and Laboratory Standards Institute, which is the most common assay used in antibiotic ones. Therefore, we conclude that to have relevant results on antimicrobial effects of biogenic silver-based nanoparticles, it is necessary to have a complete and adequate characterization of these nanostructures, followed by standard methodology in microbiology protocols.

Background The use of silver diamine fluoride (SDF) in caries treatment in children has increased despite the disadvantage of causing tooth discoloration. Nanosilver fluoride (NSF) is a possible alternative. This study aimed to assess the antibacterial effect of NSF and SDF and their impact on the activity of dentin caries in primary teeth. Methods Synthesis and characterization of the physical and biological properties of NSF were conducted. Fifty children aged 4–6 years with dentin caries (active caries corresponding to ICDAS code 5) in deciduous teeth were randomly assigned to treatment by NSF or SDF. Baseline assessment of Streptococcus mutans ( S. mutans ) and lactobacilli counts as CFU/mL in caries lesions was done, followed by the application of the agents. After one month, microbiological samples were recollected, and lesion activity was reassessed. Groups were compared using Mann–Whitney and Chi-Square tests, while intragroup comparisons were done using Wilcoxon and McNemar tests. Multilevel logistic regression analysis was used to assess the effect of different variables on the outcomes. Results There were 130 teeth in 50 children; mean ± SD age = 4.75 ± 0.76 years, 63% were posterior teeth. At the one-month follow-up appointment, both groups showed a significant decrease from baseline bacterial counts. There was a significant difference in the reduction of S. mutans between NSF and SDF (21.3% and 10.5%, respectively, p  = 0.002), while not in lactobacilli (13.9% and 6.0%, respectively, p  = 0.094). In both groups, there was a significant reduction in the number of active caries from baseline ( p  < 0.0001) with no significant difference between groups (percentage inactive = 64.4% and 63.4%, p  = 0.903). Multilevel regression revealed non-significant differences in S. mutans and lactobacilli counts (AOR 1.281, p  = 0.737 and 1.888, p  = 0.341, respectively), and in the number of inactive lesions (AOR 1.355, p  = 0.731) between groups. Conclusion The short-term antibacterial efficacy of NSF was similar to that of SDF. In both groups there was a significant reduction of S. mutans and lactobacilli counts in active dentin caries, and two-thirds of the lesions became inactive with no differences between the two interventions. Further research is needed to investigate the long-term efficacy of NSF and its suitability for clinical use in caries management. Trial registration : This trial was prospectively registered on the clinicaltrials.gov registry with ID: NCT05221749 on 03/02/2022.

Background Silver nanoparticles (AgNPs) are an important class of nanomaterials used as antimicrobial agents for a wide range of medical and industrial applications. However toxicity of AgNPs and impact of their physicochemical characteristics in in vivo models still need to be comprehensively characterized. The aim of this study was to investigate the effect of size and coating on tissue distribution and toxicity of AgNPs after intravenous administration in mice, and compare the results with those obtained after silver acetate administration. Methods Male CD-1(ICR) mice were intravenously injected with AgNPs of different sizes (10 nm, 40 nm, 100 nm), citrate-or polyvinylpyrrolidone-coated, at a single dose of 10 mg/kg bw. An equivalent dose of silver ions was administered as silver acetate. Mice were euthanized 24 h after the treatment, and silver quantification by ICP-MS and histopathology were performed on spleen, liver, lungs, kidneys, brain, and blood. Results For all particle sizes, regardless of their coating, the highest silver concentrations were found in the spleen and liver, followed by lung, kidney, and brain. Silver concentrations were significantly higher in the spleen, lung, kidney, brain, and blood of mice treated with 10 nm AgNPs than those treated with larger particles. Relevant toxic effects (midzonal hepatocellular necrosis, gall bladder hemorrhage) were found in mice treated with 10 nm AgNPs, while in mice treated with 40 nm and 100 nm AgNPs lesions were milder or negligible, respectively. In mice treated with silver acetate, silver concentrations were significantly lower in the spleen and lung, and higher in the kidney than in mice treated with 10 nm AgNPs, and a different target organ of toxicity was identified (kidney). Conclusions Administration of the smallest (10 nm) nanoparticles resulted in enhanced silver tissue distribution and overt hepatobiliary toxicity compared to larger ones (40 and 100 nm), while coating had no relevant impact. Distinct patterns of tissue distribution and toxicity were observed after silver acetate administration. It is concluded that if AgNPs become systemically available, they behave differently from ionic silver, exerting distinct and size-dependent effects, strictly related to the nanoparticulate form.

Background The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs) and silver acetate (AgAc) to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food and food contact materials. Results AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume) and stabilized in aqueous suspension by the polymer polyvinylpyrrolidone (PVP). The AgNPs remained stable throughout the duration of the 28-day oral toxicity study in rats. The organ distribution pattern of silver following administration of AgNPs and AgAc was similar. However the absolute silver concentrations in tissues were lower following oral exposure to AgNPs. This was in agreement with an indication of a higher fecal excretion following administration of AgNPs. Besides the intestinal system, the largest silver concentrations were detected in the liver and kidneys. Silver was also found in the lungs and brain. Autometallographic (AMG) staining revealed a similar cellular localization of silver in ileum, liver, and kidney tissue in rats exposed to AgNPs or AgAc. Using transmission electron microscopy (TEM), nanosized granules were detected in the ileum of animals exposed to AgNPs or AgAc and were mainly located in the basal lamina of the ileal epithelium and in lysosomes of macrophages within the lamina propria. Using energy dispersive x-ray spectroscopy it was shown that the granules in lysosomes consisted of silver, selenium, and sulfur for both AgNP and AgAc exposed rats. The diameter of the deposited granules was in the same size range as that of the administered AgNPs. No silver granules were detected by TEM in the liver. Conclusions The results of the present study demonstrate that the organ distribution of silver was similar when AgNPs or AgAc were administered orally to rats. The presence of silver granules containing selenium and sulfur in the intestinal wall of rats exposed to either of the silver forms suggests a common mechanism of their formation. Additional studies however, are needed to gain further insight into the underlying mechanisms of the granule formation, and to clarify whether AgNPs dissolve in the gastrointestinal system and/or become absorbed and translocate as intact nanoparticles to organs and tissues.

Increase in bacterial resistance to commonly used antibiotics is a major public health concern generating interest in novel antibacterial treatments. Aim of this scientific endeavor was to find an alternative efficient antibacterial agent from non-conventional plant source for human health applications. We used an eco-friendly approach for phyto-fabrication of silver nanoparticles (AgNPs) by utilizing logging residue from timber trees Gmelina arborea (GA). GC–MS analysis of leaves, barks, flowers, fruits, and roots was conducted to determine the bioactive compounds. Biosynthesis, morphological and structural characterization of GA-AgNPs were undertaken by UV–Vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). GA-AgNPs were evaluated for antibacterial, antibiofilm, antioxidant, wound healing properties and their toxicity studies were carried out. Results identified the presence of terpenoids, sterols, aliphatic alcohols, aldehydes, and flavonoids in leaves, making leaf extract the ideal choice for phyto-fabrication of silver nanoparticles. The synthesis of GA-AgNPs was confirmed by dark brown colored colloidal solution and spectral absorption peak at 420 nm. Spherical, uniformly dispersed, crystalline GA-AgNPs were 34–40 nm in diameter and stable in solutions at room temperature. Functional groups attributed to the presence of flavonoids, terpenoids, and phenols that acted as reducing and capping agents. Antibacterial potency was confirmed against pathogenic bacteria Bacillus cereus , Escherichia coli , Pseudomonas aeruginosa , and Staphylococcus aureus by disc diffusion assay, MIC and MBC assay, biofilm inhibition assay, electron-microscopy, cell staining and colony counting techniques. The results from zone of inhibition, number of ruptured cells and dead - cell - count analysis confirmed that GA-AgNPs were more effective than GA-extract and their bacteria inhibition activity level increased further when loaded on hydrogel as GA-AgNPs-PF127, making it a novel distinguishing feature. Antioxidant activity was confirmed by the free radical scavenging assays (DPPH and ABTS). Wound healing potential was confirmed by cell scratch assay in human dermal fibroblast cell lines. Cell-proliferation study in human chang liver cell lines and optical microscopic observations confirmed non-toxicity of GA-AgNPs at low doses. Our study concluded that biosynthesized GA-AgNPs had enhanced antibacterial, antibiofilm, antioxidant, and wound healing properties.

Background Silver diamine fluoride (SDF) is indicated for the management of early childhood caries (ECC). Similarly, nanosilver fluoride (NSF) is effective against caries. However, there are limited comparisons between both agents, especially regarding their antibacterial effect. This randomized controlled clinical trial aimed to compare the effects of SDF and NSF on salivary bacterial counts in children with ECC. Methods Fifty 4-6-year-olds presenting with active dentin caries (ICDAS code 5) in primary teeth were randomly allocated to two groups. Streptococcus mutans (S. mutans) and Lactobacilli in unstimulated saliva were cultivated on differential media and counted as colony-forming units. Followed by the application of either 38% SDF or NSF. Saliva samples were recollected after one month. The legal guardians completed a detailed questionnaire assessing their child’s dental hygiene habits, dental pain experience, and socioeconomic background. Multivariable binary logistic regression was used to assess the effects of both agents on bacterial counts while accounting for confounders. Results The mean age of participants was 4.8 ± 0.8 years, with the majority (96%, N  = 48) presenting with severe ECC. There were no statistically significant differences between the two groups regarding age, sex, dmft score, socioeconomic background, dental hygiene habits, or dental experience. After one month, within-group analysis showed a significant reduction in S. mutans only in the NSF group ( p  = 0.002) and significant decreases in Lactobacilli counts in both SDF and NSF groups ( p  < 0.05). However, between-group comparisons revealed no significant differences in the reduction of S. mutans (1.4% and 6.0%, respectively, p  = 0.192) or Lactobacilli counts (6.0% and 6.0%, respectively, p  = 0.754). Regression analyses revealed non-significant odds of reduced bacterial counts after NSF application compared to SDF. Conclusion After one application, children with ECC showed significant decrease in salivary bacteria, with no difference between the two agents regarding their antibacterial effect. NSF can serve as a viable option in ECC management in that it provides comparable antibacterial effects to 38% SDF without inducing tooth discoloration. This trial was prospectively registered on the clinicaltrials.gov registry with ID: NCT05221749 on 03/02/2022.

Background Silver diamine fluoride (SDF) solution is effective in arresting early childhood caries (ECC). Previous studies have suggested that it might exert a preventive effect in managing ECC. However, no well-designed clinical trials have yet been performed to study the effect of SDF on caries prevention. The objective of this randomised clinical trial is to determine whether 38% SDF solution is superior to 5% sodium fluoride (NaF) varnish in preventing new carious lesions in primary anterior teeth. Methods/design This is a phase II, single-centre, randomised, double-blind, active-controlled, parallel-group pragmatic trial. The hypothesis tested is that 38% SDF would be more effective than 5% NaF in preventing new caries development in primary anterior teeth. Approximately 730 3-year-old children who are generally healthy and with parental consent will be recruited from Hong Kong kindergartens. This sample size will be sufficient for appropriate statistical analysis of a superiority trial with 90% power, allowing for a 20% drop-out rate. Stratified randomisation will be adopted for allocating the intervention. The intervention will either be 38% SDF or 5% NaF (as a positive control) therapy on primary upper anterior teeth. A single trained examiner will conduct a dental examination every 6 months until 30 months in kindergarten. Another operator will provide fluoride therapy immediately after each dental examination. The examiner, children and children’s parents will be blinded to the treatment allocation. A questionnaire survey will be conducted to study the children’s oral health-related behaviours and socioeconomic backgrounds. Chi-square tests, t tests, regression analyses and survival analyses will be adopted for data analysis. Discussion The effectiveness of 38% SDF in preventing ECC remains uncertain. If the results are as anticipated, care standards using 5% NaF for ECC prevention will be changed. In addition, the results will be widely available and increase the adoption of SDF in other countries to reduce the global burden of ECC. Trial registration ClinicalTrials.gov, NCT04075474 . Registered on 30 Aug 2019.

The present study reports the synergistic antibacterial activity of biosynthesized silver nanoparticles (AgNPs) with the aid of a combination of chitosan and seaweed-derived polyphenols as a green synthetic route. Under optimum synthesis conditions, the rapid color change from yellowish to dark brown and UV-visible absorption peak at 425 confirmed the initial formation of AgNPs. DLS, TEM, XRD, and EDX analyses revealed the spherical shape of pure biogenic AgNPs with a mean diameter size of 12 nm ± 1.5 nm, and a face-centered cubic crystal structure, respectively. FTIR and TGA results indicated the significant contribution of chitosan and polyphenol components into silver ions bioreduction and thermal stability of freshly formed AgNPs. Long-term colloidal stability of AgNPs was obtained after 6-month storage at room temperature. The bio-prepared AgNPs possessed a negative surface charge with a zeta potential value of - 27 mV. In contrast to naked chemical silver nanoparticles, the green Ag nanosamples demonstrated the distinct synergistic antibacterial in vitro toward all selected human pathogens presumably due to the presence of high content of biomolecules on their surface. The results show that synergy between chitosan and polyphenol results in the enhancement of bactericidal properties of biogenic AgNPs. We also highlighted the underlying mechanism involved in AgNPs formation based on nucleophile-electrophile interaction.