Strains Of Streptococcus Mutans Research Articles

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

BackgroundFluoride-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.ObjectiveThis study aimed to identify metabolites that discriminate fluoride-resistant from wild-type S. mutans.Materials and methodsCell 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).ResultsFourteen 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.ConclusionsThe 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.

Cellulose Nanocrystals Show Anti-Adherent and Anti-Biofilm Properties against Oral Microorganisms.

Cellulose nanocrystals (CNCs) are cellulose-derived nanomaterials that can be easily obtained, e.g., from vegetable waste produced by circular economies. They show promising antimicrobial activity and an absence of side effects and toxicity. This study investigated the ability of CNCs to reduce microbial adherence and biofilm formation using in vitro microbiological models reproducing the oral environment. Microbial adherence by microbial strains of oral interest, Streptococcus mutans and Candida albicans, was evaluated on the surfaces of salivary pellicle-coated enamel disks in the presence of different aqueous solutions of CNCs. The anti-biofilm activity of the same CNC solutions was tested against S. mutans and an oral microcosm model based on mixed plaque inoculum using a continuous-flow bioreactor. Results showed the excellent anti-adherent activity of the CNCs against the tested strains from the lowest concentration tested (0.032 wt. %, p < 0.001). Such activity was significantly higher against S. mutans than against C. albicans (p < 0.01), suggesting a selective anti-adherent activity against pathogenic strains. At the same time, there was a minimal, albeit significant, anti-biofilm activity (0.5 and 4 wt. % CNC solution for S. mutans and oral microcosm, respectively, p = 0.01). This makes CNCs particularly interesting as anticaries agents, encouraging their use in the oral field.

Miswak-Infused Glass Ionomer Cement: A Comparative In Vitro Analysis of Antibacterial Efficacy and Compressive Strength.

Glass ionomer cement (GIC) restorations are commonly used in primary dentition, due to their aesthetic appeal, self-adhesive nature, and biocompatibility. However, the material's limited antibacterial activity and inadequate mechanical strength highlight the necessity for modifying the material. The study aims to evaluate and compare the antimicrobial potency and compressive strength of GIC-incorporated Miswak extract with that of conventional GIC. After obtaining the Miswak extract, a modified GICwas formulated by combining the extract with the conventional GIC powder and liquid components, in three different ratios (Powder: Extract and Liquid), Group I (2:1:1), Group II (3:1:2), Group III (3:2:1), and the Group IV as control, which consist of unmodified/conventional GIC. To evaluate and compare the antibacterial efficacy of the modified and unmodified GIC, standard strains of Streptococcus mutans and Lactobacillus were utilized. For each group, the minimal inhibitory concentration (MIC) assay was tested. For the evaluation of compressive strength, cylindrical moulds were utilized in compliance with ISO 9917-1:2007 standards and tested using the universal testing machine (Instron, ElectroPuls®, Bangalore, IND). The highest force exerted at the point of specimen fracture was recorded to calculate the compressive strength values in MPa. The data obtained were analyzed using the StatisticalPackage for the Social Sciences (IBMSPSSStatisticsforWindows,IBMCorp., Version 24.0, Armonk,NY)software. The statistical analysis was conducted utilizing repeated measures of analysis of variance (ANOVA) to calculate the mean MICvalues and compressive strength, with pairwise comparisons assessed using Tukey's post hoc test. The results provedthat the antimicrobial properties of Miswak containing GIC performed better against S. mutans and Lactobacillus with a statistically significant difference when compared with group IV (p<0.05), it has been found that an increase in the concentration of extract increased the antimicrobial potency. Significant results were obtained in compressive strength where GroupII (41.49±3.6) and Group III (15.23±4.96) proved to be weaker than the control (62.69±2.58), while Group I showed no differences from the control group (p>0.05). It can be concluded that Group I was found to be better in terms of both antimicrobial properties and compressive strength, where no significant difference in compressive strength was identified when comparing Group I with Group IV. Thus, the overall study depicts that a lesser concentration of extract can be the best option in terms of good antimicrobial properties without altering its strength. Hence, the Miswak containing GIC could be a promising restorative material; further studies should include considering intraoral variables such as masticatory stress, moisture levels and in-vivo tests of this combination.

Association of Papacarie Duo® and low-level laser in antimicrobial photodynamic therapy (aPDT).

Dental caries is a multifactorial, non-communicable disease. Effective treatment options for minimally invasive removal of carious tissue include Papacarie Duo® gel and antimicrobial photodynamic therapy (aPDT). aPDT involves a combination of a light source and photosensitizer. Given that Papacarie Duo® contains a percentage of blue dye, this study aims to explore the antimicrobial potential of Papacarie Duo® when associated with a light source against Streptococcus mutans strains. The chosen light source was a low-power diode laser (λ = 660nm, E = 3J, P = 100 mW, t = 30s). To assess antimicrobial capacity, planktonic suspensions of Streptococcus mutans were plated on Brain Heart Infusion Agar (BHI) to observe the formation of inhibition halos. The studied groups included methylene blue (0.005%), Papacarie Duo®, distilled water (negative control), 2% chlorhexidine (positive control), Papacarie Duo® + laser, and methylene blue (0.005%) + laser. Following distribution onto plates, each group was incubated at 37°C for 48h under microaerophilic conditions. Inhibition halos were subsequently measured using a digital caliper. The results showed that chlorhexidine had the greatest antimicrobial effect followed by the group of irradiated methylene blue and irradiated Papacarie Duo®. All experimental groups demonstrated antimicrobial potential, excluding the negative control group. The study concludes that Papacarie Duo® exhibits antimicrobial properties when associated with a low-power diode laser.

CHEMICAL CONSTITUENTS AND ANTIBACTERIAL ACTIVITY OF THREE TYPES OF AMAZONIAN Melipona spp. GEOPROPOLIS

This work describes the first chemical study on the metabolic profile of three geopropolis samples from Melipona fulva, M. compressipes, and M. paraensis collected in the Amazonian region. The samples were submitted to solvent extractions. The silylated hexane extracts were submitted to GC-MS analysis and tentatively identified mainly the presence of triterpenes, steroids, fatty acids, and alcohols. The chemical profile of M. fulva of and M. compressipes geopropolis are similar. However, cholesterol, triacontanol, and palmitic acid are the main compounds in M. fulva; in M. compressipes, palmitic acid, linoleic acid, and oleic acid are predominant. The chemical profile of the M. paraensis sample is entirely different once more than 60% of the extract comprises lupenone and triacontanol. The CHCl3 soluble fraction of the MeOH extract of the M. paraensis geopropolis was submitted to chromatographic techniques, and it afforded cycloartenol, 24-methylene-cycloartenol, lupeol, α- and β-amirins, and 7-O-methylaromadendrin. The MeOH extract of this sample presents antimicrobial activities against strains of Streptococcus mutans, S. sobrinus, and S. aureus (MIC of 15.6-62.5 µg mL-1 and MBC of 62.5-1000 µg mL-1). The M. fulva and M. compressipes geopropolis were not active in this test.

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.

Influence of Passive Ultrasonic Irrigation of the Photosensitizer Used in Photodynamic Therapy on Microbial Reduction in the Root Canal System: An in Vitro Study.

The success of endodontic treatment is based on microbial reduction promoted by the interaction of chemical and mechanical procedures. Photodynamic therapy (PDT) is used as an adjunct to conventional treatment, with significant microbial reduction. This study aimed to evaluate the influence of passive ultrasonic irrigation (PUI) of the photosensitizer (PS) used in PDT on microbial reduction in the root canal system. Forty-five mesiobuccal root canals from extracted human mandibular molars that were inoculated with standard strains of Enterococcus faecalis, Candida albicans, and Streptococcus mutans for 21 days were selected. The root canals were prepared using the ProTaper Next system and randomly divided into 3 groups (n=15): 1) PDT: PDT alone; 2) PUI+PDT: PUI followed by PDT; and 3) PUI/PS+PDT: PUI of the PS followed by PDT. Microbiological samples were collected from the canals before and after using the protocols described above. The data were analyzed by analysis of variance (Tukey's test) at a significance level of 5%. Microbial counts before PDT, PUI+PDT, and PUI/PS+PDT did not differ significantly (P>0.05), showing methodological standardization in the microbial contamination of the root canal system. There was a significant reduction in microbial counts after PDT (61.05%), PUI+PDT (65.04%), and PUI/PS+PDT (68.58%) (P<0.01), but with no statistically significant difference between the three groups (P>0.05). Based on the present findings, it was concluded that the combination of PUI with PDT or PS activation did not influence microbial reduction achieved by PDT alone.

Effect of ethanolic extract of propolis on antibacterial and microshear bond strength of glass-ionomer restorations to dentin

ObjectivesThis study was conducted to evaluate the effect of ethanolic extract of propolis on antibacterial and microshear bond strength of glass ionomer restorations to dentin. Materials and methodsConventional glass ionomer cement (Equia forte, GC Tokyo, Japan), resin-modified glass ionomer (Fuji II LC, GC Tokyo, Japan) and propolis powder (dried extract from honey bees) materials were used in this study. Both conventional glass ionomer and resin-modified glass ionomer were modified by two different concentrations of ethanolic extract of propolis (10 % and 25 % EEP). For antibacterial test, Streptococcus mutans strain was spread on agar petri dishes using a sterile swab. Discs of both glass ionomer restorative materials (without adding EEP, with 10 % EEP and with 25 % EEP) were fabricated within the agar plates. Antibacterial activity was evaluated by measuring the inhibition zones around each disc. For microshear bond strength test, 60 healthy human permanent molars were prepared by cutting occlusal surface and expose the dentin at the height of contour of all teeth then conditioned using poly acrylic acid conditioner, both glass ionomer restorative materials (without adding EEP, with 10 % EEP and with 25 % EEP) were mixed and applied on conditioned dentin surface by using tygon tube. Microshear bond strength was evaluated by the universal testing machine. ResultsTwo-way ANOVA test revealed that both glass ionomer type and different concentrations of EEP had significant effect on the antibacterial test results and microshear bond strength values (p < 0,05). Glass ionomer restorative material with 25%EEP had the highest antibacterial values whereas glass ionomer restorative material without modifications (control groups) had the lowest values. Resin-modified glass ionomer without any modification (control group) had the highest bond strength while resin-modified glass ionomer with 25%EEP had the lowest bond strength. ConclusionsIncorporation of ethanolic extract of propolis to glass ionomer restorative material increases the antibacterial effects of both conventional GIC and RMGI. Inspite of this advantage, it seems that it has deleterious effect on microshear bond strength to dentin.

Human-associated bacteria adopt an unusual route for synthesizing 3-acetylated tetramates for environmental adaptation

BackgroundTetramates or tetramic acid-containing compounds (TACs) are a group of bioactive natural products featuring a pyrrolidine-2,4-dione ring acknowledged being closed via Dieckmann cyclization. The cariogenic Streptococcus mutans strains bearing a muc biosynthetic gene cluster (BGC) can synthesize mutanocyclin (MUC), a 3-acetylated TAC that can inhibit both leukocyte chemotaxis and filamentous development in Candida albicans. Some strains can also accumulate reutericyclins (RTCs), the intermediates of MUC biosynthesis with antibacterial activities. However, the formation mechanism of the pyrrolidine-2,4-dione ring of MUC and the distribution of muc-like BGCs along with their ecological functions has not been explored extensively.ResultsWe demonstrated that a key intermediate of MUC biosynthesis, M-307, is installed by a hybrid nonribosomal peptide synthetase-polyketide synthase assembly line and its pyrrolidine-2,4-dione ring is closed via an unprecedented lactam bond formation style. Subsequent C-3 acetylation will convert M-307 to RTCs, which is then hydrolyzed by a deacylase, MucF, to remove the N-1 fatty acyl appendage to generate MUC. Distribution analysis showed that the muc-like BGCs distribute predominantly in human-associated bacteria. Interestingly, most of the muc-like BGCs possessing a mucF gene were isolated from human or livestock directly, indicating their involvement in alleviating the host’s immune attacks by synthesizing MUC; while those BGCs lacking mucF gene distribute mainly in bacteria from fermented products, suggesting that they tend to synthesize RTCs to compete with neighboring bacteria. It is noteworthy that many bacteria in the same habitats (e.g., the oral cavity) lack the muc-like BGC, but possess functional MucF homologues to “detoxify” RTCs to MUC, including several competitive bacteria of S. mutans. We also comparably studied the distribution of TAS1, a fungal enzyme responsible for the production of phytotoxic tenuazonic acids (TeAs), a class of 3-acetylated TACs with similar structure but distinct biosynthetic mechanism to MUC, and found that it mainly exists in plants or crops.ConclusionsThe in vivo and in vitro experiments revealed that the pyrrolidine-2,4-dione ring of MUC is closed via lactam bond formation, which may be adopted by many TACs without 3-acyl decorations. Besides, we found that muc-like BGCs are widespread in human-associated bacteria and their shapes and main products can be influenced by the habitat environment and vice versa. By comparing with TeAs, we provided thought-provoking insights into how ecological and evolutionary forces drive bacteria and fungi to construct a common 3-acetylated pyrrolidine-2,4-dione core through different routes, and how the biosynthetic processes are delicately controlled to generate diverse 3-acetylated TACs for environmental adaptation.2PMNhDpkP3itX1xdtgrn3CVideo

Evaluation of Probiotic Effects of Lactobacilli on Mutans Streptococci: An In Vitro Study.

The aim of the present study is to evaluate the probiotic effect of Lactobacillus acidophilus and Lactobacillus rhamnosus on clinical isolates of Mutans Streptococci (MS) and antibiotic susceptibility of these strains to commonly used antibiotics in dentistry. Plaque samples from permanent first molars were collected and transferred aseptically onto Mitis-Salivarius agar and incubated at 37°C for 24 hours in the presence of 5-10% CO2. Mutans streptococci colonies were identified biochemically using Hi-Strep identification kit. The inhibitory activity of the clinical strains of MS on Lactobacilli was investigated using agar-overlay interference technique. Positive inhibition was appreciated as a clear zone around the Lactobacilli. Disk diffusion assay was done as described by CLSI M100-S25 for antibiotic susceptibility. The zone of growth inhibition caused by Lactobacilli and antibiotics on MS clinical strains was measured directly using a vernier caliper. Statistical analysis was done using independent t-test. Mutans streptococci exhibited positive inhibition with both the probiotic strains and L. acidophilus showed more zones of inhibition than L. rhamnosus. Antibiotic susceptibility of clinical strains of MS showed sensitivity to penicillin and vancomycin, however, tetracycline and erythromycin showed very few resistant strains. The highest zone of inhibition was shown by cephalothin followed by penicillin, tetracycline, ciprofloxacin, erythromycin, and vancomycin. L. rhamnosus and L. acidophilus have strong inhibitory effects on clinical strains of MS. Lactobacillus acidophilus showed a higher zone of inhibition. All the clinical strains of MS were sensitive to penicillin and vancomycin. The highest zone of inhibition was shown by cephalothin. Dental caries remains silent epidemic and increasing antibiotic resistance is another major challenge that threatens the world. Newer methods such as whole-bacteria replacement therapy using probiotics for decreasing harmful oral pathogens and reducing the intake of antibiotics must be explored. More researches to promote use of probiotics should be initiated due to its possible preventive and health maintenance benefits providing an end to new cavities and antibiotic resistance.

Antimikrobna aktivnost hlorheksidina i sastav čestica cerijum-oksida

Introduction. Antiseptics are non-specific antimicrobial drugs that are widely used in dentistry. The "gold standard" in periodontology is chlorhexidine digluconate (CHG). A widespread use of CHG-containing products for daily care in medicine and dentistry and other fields leads to acquiring resistance to CHG in microorganisms. Methods. A macro method of serial dilution was used for the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) on clinical strains of Streptococcus mutans (S. mutans) and Staphylococcus epidermidis (S. epidermidis) obtained from the patients with associated dental plaque-induced gingivitis, whereas museum strains of Escherichia coli (E. coli) ATCC25922 and Candida albicans (C. albicans) ATCC10231 were used as inoculum. Results. The MIC and MBC of CHG, cerium oxide nanoparticles (CeNPs) and the solution of the CeNPs and CHG were tested. It was found that CeNPs itself had a weak inhibitory and bactericidal effect on microorganisms. The composition of CHG and CeNPs had significantly higher MIC and MBC for clinical cultures S. mutans and S. epidermidis; museum strains of E. coli ATCC25922 and C. albicans ATCC10231 were compared with CHG alone. Conclusion. This method significantly enhanced bactericidal and bacteriostatic activity of chlorhexidine digluconate against clinical and museum strains of microorganisms.

L-arginine-containing mesoporous silica nanoparticles embedded in dental adhesive (Arg@MSN@DAdh) for targeting cariogenic bacteria

Dental caries is the major biofilm-mediated oral disease in the world. The main treatment to restore caries lesions consists of the use of adhesive resin composites due to their good properties. However, the progressive degradation of the adhesive in the medium term makes possible the proliferation of cariogenic bacteria allowing secondary caries to emerge. In this study, a dental adhesive incorporating a drug delivery system based on L-arginine-containing mesoporous silica nanoparticles (MSNs) was used to release this essential amino acid as a source of basicity to neutralize the harmful acidic conditions that mediate the development of dental secondary caries. The in vitro and bacterial culture experiments proved that L-arginine was released in a sustained way from MSNs and diffused out from the dental adhesive, effectively contributing to the reduction of the bacterial strains Streptococcus mutans and Lactobacillus casei. Furthermore, the mechanical and bonding properties of the dental adhesive did not change significantly after the incorporation of L-arginine-containing MSNs. These results are yielding glimmers of promise for the cost-effective prevention of secondary caries.Graphical

In vitro antimicrobial and cytotoxic activity of Neem and Kirata herbal formulation mediated Silver nanoparticles.

Silver nanoparticles (AgNPs) gain great interest among noble metal nanoparticles due to their broad applications in medicine, dentistry, drug delivery, tissue and tumour imaging, biolabeling, and biosensing. The antibacterial, antifungal, antiviral, and antiparasitic activity of AgNPs is well documented in the literature. This study aimed to determine the antimicrobial and cytotoxic activity of Neem and Kirata herbal formulation-mediated silver nanoparticles against oral biofilm. The green synthesis of Neem and Kirata herbal formulation-mediated silver nanoparticles was done. The antimicrobial action against the strains of Candida albicans, Staphylococcus aureus, Enterococcus faecalis, and Streptococcus mutans were assessed. The results showed that the newly formulated nanoparticle had effective anti-microbial properties and decreased cytotoxic properties which make it advantageous for clinical applications and treatment modalities. It showed great potential for the nanoparticle in decreasing the bacterial effects and cytotoxic nature thereby providing future scope for clinical application in preventing oral biofilm formation and its deleterious effects.

The antibiofilm activity of selected substances used in oral health prophylaxis

Oral health is a window to a patient’s general well-being. Balance in oral microbiome functions is crucial for health maintenance. A state of oral dysbiosis may lead to a variety of local and systemic pathological conditions. The presence of dental plaque is related to the majority of oral infections. Proper oral hygiene is crucial and the most economic practice contributing to oral health prophylaxis. Aside from prophylactic treatments provided by dental practitioners, mouth rinses, containing antimicrobial agents, are one of the possible tools used for oral care. Our study was to determine whether available mouth rinses and selected products dedicated for professional use are efficient to eradicate biofilm formed by reference and clinical strains of Streptococcus mutans, Streptococcus sanguinis, Streptococcus oralis, Streptococcus mitis, Staphylococcus aureus, Enterococcus faecalis, Lactobacillus rhamnosus and Candida albicans on the surface of hydroxyapatite – major mineral component of a tooth. Therefore, such antimicrobials as chlorhexidine, cetylpyridine chloride, polyhexanide, silver nanoparticles, sulphonated phenolics, and natural antiplaque essential oils and coconut oil were analyzed. Applied experimental settings in in vitro models were designed to reflect accurately the recommended use of the tested substances, therefore four types of eradication procedure were conducted. Sialorrhea simulation was also performed to evaluate antibiofilm potential of diluted mouth rinses. Biofilm was investigated with quantitative method where absorbance values were measured. Statistical differences were assessed using the Kruskal–Wallis test with a post-hoc Dunnett’s analysis. Results have shown that biofilms displayed a diversified sensitivity to the tested antimicrobials. The highest antibiofilm activity was detected for cetylpyridine chloride while the lowest for chlorhexidine. However the differences in E. faecalis biofilm reduction observed after the use of these two compounds were not statistically significant (p > 0.05), whereas all observed differences in S. aureus survival after exposure to the examined antimicrobial agents were statistically significant (p < 0.5). The PHMB, both in standard and in sialorrhea simulated conditions had the highest potential against streptococci. The coconut oil reduced C. albicans fungus biofilm by 65.48% but low eradication level was observed in case of bacterial biofilms. The dehydrating mechanism of action of sulfonated phenolics turned out to be ineffective against streptococcal biofilm which in turn was effectively eradicated by silver nanoparticles. The implementation of Antibiofilm Dressing's Activity Measurement method allowed to observe strain-related differences in terms of antimicrobial sensitivity. The obtained results may be introduced in everyday out-patient dental plaque prophylaxis as well as clinical environment.

Bioactive isopimarane and 3,4-seco isopimarane diterpenoids from Isodon amethystoides

Isodon amethystoides (Lamiaceae) is a popular plant in folk medicine in the southern provinces of China. Our phytochemical investigation of the twigs and leaves of this plant led to the discovery of five new diterpenoids with isopimarane and 3,4-seco isopimarane scaffolds [isoamethinols A–E (1–5)], along with the known compound 3,4-seco isopimara-4(18),7,15-triene-3-oic acid methylester (6). The chemical structures of these compounds, including the absolute configurations of the new diterpenoids, were determined by comprehensive spectroscopic analyses and single crystal X-ray diffraction measurements. These compounds were evaluated for their biological activities against a panel of human cancer cell lines, gram-positive bacterial strains and HIV. Notably, the 3,4-seco-isopimarane isoamethinol D (4) showed toxicity to the cervical Hela cancer (Hela) cells with an IC50 value of 27.21 μM and the lung (A549) cancer cells with an IC50 value of 21.47 μM. Compound 4 also exhibited mild antimicrobial activity against the oral bacterial strain Streptococcus mutans. These findings suggested that the diterpenoids with a 3,4-seco-isopimarane diterpenoids isolated from I. amethystoides could provide a novel structure scaffold for the discovery of anticancer and antimicrobial compounds.Graphical

Morphological, chemical and antimicrobial analysis of glass ionomer cements used for ART in posterior primary teethGlass ionomer cements (GICs) have been gaining prominence as material for atraumatic restorative treatment (ART) due to their acceptable ph

Glass ionomer cements (GICs) have been gaining prominence as material for atraumatic restorative treatment (ART) due to their acceptable physicochemical and biological properties. Objective: To analyze the surface morphology, chemical constitution, and antimicrobial action of GICs used for ART in posterior primary teeth. Material and methods: The tested materials were Vitro Molar®, Ketac Cem Easymix® and Riva Self Cure®. For the structural and chemical analysis, polyethylene tubes with an internal diameter of 3 mm and 3 mm in length were prepared, filled, and then transferred to a chamber with 95% relative humidity and a temperature of 37oC. The surface morphology of the tested materials was examined by scanning electron microscopy (SEM) and main components were investigated by energy-dispersive X-ray microanalysis. For the antimicrobial efficacy analyses, strains of Streptococcus mutans (ATCC 27853) were used. Petri dishes with brain heart infusion agar (BHIA) were inoculated with the microbial suspensions and three cavities were made in each agar plate and filled with one of the GICs. The plates were pre-incubated for 1 hour at room temperature and then incubated at 37oC for 24 to 48 hours. The inhibition zone around each well was recorded in mm. Results: SEM revealed irregular and rough external surface. Cracking was not observed. The main constituents were found to be aluminum, silicon, sodium, and fluoride. Barium was only observed in Vitro Molar®, while lanthanum was only observed in Ketac Cem Easymix®. Elemental mapping of the outer surface revealed high concentration of aluminum and silicon. Inhibition halos were only observed in Riva Self Cure®. Conclusion: The GICs presented irregular outer surfaces and similar chemical elements. Only Riva Self Cure® showed antibacterial action against the S. mutans.

Clinical characteristics of children and guardians possessing CBP-positive Streptococcus mutans strains: a cross-sectional study

Streptococcus mutans is a major etiological agent for dental caries. We previously demonstrated that S. mutans strains expressing collagen-binding proteins (CBPs) were related to the pathogenesis of systemic diseases. However, their acquisition and colonization remain unknown. Here, we investigated the detection rates of CBP-positive S. mutans strains in children and their guardians to clarify the background for the acquisition and colonization in children. Saliva samples were collected from children and their mothers, and detection of S. mutans and collagen-binding genes (cnm, cbm) was performed by PCR after DNA extraction. The oral status of each child was examined, and their mothers were asked to complete a questionnaire. The isolation rate of Cnm-positive S. mutans was significantly higher in mothers than in children. Notably, the possession rates of CBP-positive strains in children were significantly higher in children whose mothers had CBP-positive strains than in children whose mothers did not have these strains. Furthermore, children with CBP-positive strains had a significantly shorter breastfeeding period than children without these strains. The present results suggest that nutritional feeding habits in infancy are one of the factors involved in the acquisition and colonization of CBP-positive S. mutans strains.

Isolation and identification of fluoride sensitive and fluoride resistant Streptococcus mutans strains from dental carries of diabetic patients using conventional methods in Sudan.

Background Dental caries also known as cavities are the most predominant disease today. Streptococcus mutans can form a biofilm on the tooth surface, produce high levels of lactic acid following fermentation of dietary sugars, and are resistant to the adverse effects of low pH, properties which are essential for oral micro biota. The aim of this study was to isolate S. mutans and characterize their antimicrobial properties against sodium fluoride. Fresh dental caries samples were collected from diabetic patients. The isolates were identified based on their acidogenic, biochemical test, and antimicrobial properties. Methods The socio-demographic data collected through a structure designated questionnaire and the biological data collected through sterile cotton swabs. For analysis of data, Statistical Package for Social Sciences software, version 23.0 (IBM SPSS Inc., Chicago, IL) was used. Results Only 32 of the 80 samples (40%) gave a positive growth for S. mutans on MSBA (mitis salivarius bacitracin agar). The sensitivity of the isolates against sodium fluoride was tested by preparing NaF of four different concentrations (80, 125, 250, and 500) mg\L. Fifty percent of isolates were found to be resistant to NaF at a concentration of 80 mg/L, while 28% were resistant to 125 mg/L NaF, 16%   to 250 mg/L and 3% to 500mg/L NaF. The majority of the participants were aged between 51–60 years (33%), were female (54%), had type II diabetes mellitus (64%), and the duration of their diabetes was less than five years (35%). Conclusions By using the information in this study, we were able to discover strains of S. mutans that are resistant to fluoride. This study can be used as an essential key to study the genetic mutation that occurred.

Enhanced mechanical properties, anti-biofilm activity, and cytocompatibility of a methacrylate-based polymer loaded with native multiwalled carbon nanotubes

ObjectivesWe aimed to optimize the mechanical and biological properties of a conventional methacrylate-based dental polymer by loading it with double- and triple-walled carbon nanotubes as growth (DTWCNTG). MethodsA formulation of bisphenol A-glycidyl methacrylate and triethylene glycol dimethacrylate (mass ratio = 2:1) was mixed with DTWCNTG at concentrations of 0.0% (control), 0.001%, 0.005%, and 0.010%. The concentrations were physicochemical and morphologically evaluated, and antibacterial activity was assessed by seeding a Streptococcus mutans strain (ATCC 25175) on the experimental polymeric surfaces. Cellular survival and osteodifferentiation were evaluated in epithelial (HaCat) and preosteoblast cells (MC3T3-E1). ResultsThe 0.001% DTWCNTG concentration yielded higher compressive strength, elastic modulus, flexural strength, flexural modulus, water sorption, and solubility than the control. The degree of conversion and color did not significantly change with a low amount of DTWCNTG incorporated into the polymer. Antibacterial activity significantly improved when tested on the 0.001% DTWCNTG discs. No groups showed cytotoxicity in a short-term analysis and adding DTWCNTG favored MC3T3-E1 mineralization over the control, particularly in the 0.001% formulation. SignificanceThe micro-addition of 0.001% DTWCNTG confers mechanical resistance, antimicrobial properties, and bioactivity to methacrylate-based polymers without significantly compromising color. Incorporating DTWCNTG improved dental composite properties and could be a biomodified material for minimally invasive procedures.

Antimicrobial photodynamic therapy as an adjunctive treatment to ultrasound for the dentin caries-like lesion removal

ObjectiveTo evaluate in vitro the efficacy of ultrasound device to remove caries-like dentin and the curcumin-mediated antimicrobial photodynamic therapy (aPDT) to decontaminate the affected dentin. MethodsBovine dentin specimens (n = 173) of 4 × 4 × 2 mm were first submitted to Knoop surface microhardness to standardize the specimens (29 ± 3 KHN). Artificial caries lesion was induced by Streptococcus mutans strain by biological model for 7 days. Infected dentin was removed (1 min) with the following techniques: dentin excavator, bur at low-speed rotation and ultrasound device. After that, aPDT application was performed using blue LED under 460 nm. Polarized light microscopy (PLM), removal rate (n = 10), cross-sectional microhardness (n = 10), colony forming units per milliliter (CFU) (n = 9) and confocal laser microscopy (CM) (n = 2) were performed. ANOVA with Welch correction, post-hoc Games-Howell and two-way ANOVA followed by Tukey's post-hoc tests were used. ResultsPLM confirmed the caries lesion formation with a depth of ∼147.9 µm. Groups treated with ultrasound showed lower removal rate (p = 0.001). Regardless of the treatment, the microhardness values increased as function of depth (p ≤ 0.05). Carbide bur showed the highest microhardness value, followed by ultrasound and excavator. CFU and CM showed a significant reduction in S. mutans after aPDT application. ConclusionUltrasound was efficient, since it removed infected dentin, preserving the affected dentin and aPDT can be used as a complementary therapy to decontaminate the affected dentin. Clinical significanceUltrasound device may help the clinician to remove dentin caries-like lesions since it is a conservative technique and provided the removal of infected dentin, preserving the affected dentin. aPDT application may be used as a complimentary technique to promote antibacterial effect and possibly minimize the risk of secondary caries.