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Background and purpose: Dental caries is a pathological infectious disease. It begins with the formation of dental plaques which is a structurally and functionally organized biofilm. Streptococcus mutans is the most important bacterium in the formation of dental plaque and dental caries. This study aimed at evaluating the antibacterial and antibiofilm activity of Quercus infectoria galls against Streptococcus mutans. Materials and methods: The bacterial strain used in this study was Streptococcus mutans (ATCC: 25923). Extracts were prepared by Soxehlet apparatus and maceration. They were then dissolved in sterile distilled water to a final concentration of 0.16 to 10.00 mg/ml. The antimicrobial activities of the extracts were determined using well diffusion method. The antibiofilm activities of the extracts were examined in a microdilution assay using TTC. Statistical analysis was performed in SPSS V.18. Results: The methanol, ethanol, and acetone extracts of Quercus infectoria galls showed strong inhibitory effects against Streptococcus mutans. The MIC values of extracts were similar and ranged from 160µg/ml to 320µg/ml, whereas the MBC values ranged from 320µg/ml to 640µg/ml. Aqueous extracts of oak galls did not show antimicrobial activity. The extracts of Quercus infectoria galls strongly inhibited the formation of Streptococcus mutans biofilms at concentrations higher than 19.5µg/ml. Conclusion: The extracts of Quercus infectoria galls displayed similarities in their antibacterial activity against Streptococcus mutans. Also, they were found effective in preventing biofilm formation of Streptococcus mutans. The galls of Quercus infectoria are considered potentially good sources of antimicrobial agent

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Background and purpose: Several factors are involved in caries prevention in children. One of the most effective factors is the appropriate use of fluoride. Fluoride induces its main effects in caries prevention through antibacterial effects and topical contact with enamel. In this study the inhibitory effects of sodium fluoride (NaF) and acidulated phosphate fluoride (APF) gels on cariogenic microorganisms concentrations (Streptococcus mutans and Lactobacillus) were compared using Quantitative Real-Time PCR.

Materials and methods: A single blind parallel clinical trial was performed in which plaque samples were investigated twice (before and after the use of fluoride). The plaque samples of 44 children were studied by quantitative Real Time PCR and the number of bacteria (lactobacilli and Streptococcus mutans) was counted in each sample. Then, APF gel (Fluoride 1.23% +0.98% phosphoric acid, pH 5.3) was randomly used for 22 children. All the teeth (primary and permanent) were covered with fluoride by applicator. For other children 2% NaF gel (neutral pH) were used. After the use of fluoride, the numbers of bacteria were measured again by quantitative real-time PCR. Finally, the variability of microorganisms before and after the intervention was compared. Mann-Whitney test was applied for data analysis using SPSS V.18.

Results: Significant reductions were observed in numbers of streptococcus mutans and lactobacillus after consumption of APF-gel (P<0.05).

Conclusion: The APF gel exhibited more caries-preventive effect compared to NaF gel and could be used to benefit children’s oral health.

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Background and purpose: Improvement of anti-bacterial properties of restorative materials to deal with microbes causing secondary caries of tooth has attracted interest of many researchers. Thus, in this study the antibacterial effect of zinc phosphate nanoparticles, synthesized with biological method, was investigated by adding it to glass ionomer cement against the Streptococcus mutans.
Materials and methods: Synthesis of the nanoparticles was carried out using two main sources of zinc nitrate and diammonium hydrogen phosphate in presence of Enterobacter aerogenes.  Furthermore, their antimicrobial effect was investigated by adding different concentrations of nanoparticles (0, 1, 2, 3, and 5%) to glass ionomer. In addition, bacterial cultures of 0.5 McFarland and its medium were added to the above mixture and were incubated in 37ºC. After 3, 6, and 24 hr they were cultured on agar plates to grow. In the end, the number of bacterial colonies grown on the plates was counted and compared.
Results: Adding nanoparticles to glass ionomer improved its antibacterial effect and this effect enhanced when the concentrations of nanoparticles increased.
Conclusion: Synthesized nanoparticles are appropriate to be added to the glass ionomer cements because of their impressive effect on inhibiting the growth of bacteria and sharing same coloring with teeth.
 

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Background and purpose: Decrease in the number of oral microorganisms leads to reduction in caries score. Bacterial therapy, such as using probiotic bacteria, is an alternative procedure in treatment of infections caused by microorganisms. The purpose of this study was to compare the effect of probiotic and non-probiotic yogurt-drink on two common oral microorganisms.
Materials and methods: In this experimental study, the minimum inhibitory concentration (MIC) of yogurt drinks and diameter of the growth inhibition zone of Streptococcus mutans and Enterococcus faecalis in probiotic and non-probiotic yogurt drinks were measured using micro broth dilution and disk agar diffusion methods, respectively. Data analysis was done in SPSS V22 applying Mann-Whitney test.
Results: The MIC of non-probiotic yogurt drink against Enterococcus faecalis and Streptococcus mutans was significantly higher than the probiotic yogurt drink (P= 0.002). The two yogurt drinks did not show any significant differences in the diameter of growth inhibition zone for S. mutans (P= 0.061) and E. faecalis (P= 0.99).
Conclusion: The study showed that probiotic yogurt drink can inhibit E. faecalis and S. mutans more than the non-probiotic yogurt drink, and it may be considered as a preventive agent for oral and dental diseases.

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Background and purpose: Secondary caries is one of the main causes for replacement of dental restorations. Glass ionomer cement (GIC) has cariostatic properties and antibacterial effect due to the ability to release fluoride. The aim of this study was to compare the antibacterial activity and fluoride release between three different formulations of GIC.
Materials and methods: This experimental study was conducted in Ardabil Dental School, Iran 2020. We evaluated fluoride release (n=15) and antibacterial activity (n=24) of three GICs including Fuji IX GP Extra, Fuji II LC, and Equia Forte against Streptococcus mutans and Lactobacillus acidophilus. Microtubes containing each bacterium and no glass ionomer were considered as positive controls. Antibacterial activity was studied using well diffusion test and time-kill curve was measured. The amount of released fluoride was measured at days 1, 2, 3, 4, 7, 14, and 21 by specific fluoride electrode. Data were analyzed applying ANOVA, post hoc Sidak, and Tukey test.
Results: Fuji IX GP Extra and Equia Forte showed significantly higher and lower antibacterial activity against both strains, respectively (P<0.001). The least fluoride release was associated with Equia Forte (P<0.001), but Fuji IX GP Extra and Fuji II LC did not show any significant difference (P>0.05).
Conclusion: Fuji IX GP Extra had the greatest growth-inhibitory effect on Streptococcus mutans and Lactobacillus acidophilus due to the highest fluoride release.

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Background and purpose: Dental caries is one of the most common bacterial diseases in childhood. Using proper dentifrice is suggested to reduce the incidence of this disease. The aim of this study was to investigate the antimicrobial effects of different brands of children's dentifrice available in Iran’s market on Streptococcus mutans (PTCC1683) and Lactobacillus acidophilus (PTCC4356) strains.
Materials and methods: After culturing standard bacterial strains, different kids dentifrice brands, including Irox, Bath, Misswake, Colgate, Oral-B, Bencer, and Frice were prepared by distilled water in 2 mg/ml and 4 mg/ml and added to pits in cultures medium. Then, the samples were incubated at 37°C for 24-48 hours and diameter of the antibacterial inhibitory haloarchaea was reported in millimeters. T-test was used for statistical analysis.
Results: All dentifrices recorded an inhibitory haloarchaea diameter of 3-25 mm (except Bath and Irox at 2 mg/ml against S. mutans, 0 mm). The antibacterial strength of dentifrices was as follows: Oral-B> Colgate> Frice> Bencer> Misswake> Bath> Irox. At 4 mg/ml, the diameter of haloarchaea against L. acidophilus was approximately twice than that of S. mutans. The mean haloarchaea diameter was not significantly different between the control group and dentifrices at 4 mg/ml against S. mutans (P= 0.080). In other conditions, the mean diameter of haloarchaea in dentifrices was lower than that of the control group (P≤0.001).
Conclusion: In this in-vitro study, Oral-B and Colgate (sodium fluoride 500 ppm) had the highest antibacterial effect and Bath and Irox (sodium monofluorophosphate 500 ppm) had the lowest antibacterial strength against the studied microorganisms. In addition, except for Bath and Irox, other dentifrices in various concentrations had desirable antibacterial properties.

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Background and purpose: Garlic and cinnamon extracts, like fluoride varnish, play a role in caries control due to their antimicrobial effect and controlling demineralization. This analytical laboratory study was conducted in 2021 to investigate the antimicrobial effect of garlic and cinnamon extracts compared with fluoride varnish in controlling the infection of oral Lactobacillus acidophilus and Streptococcus mutans.
Materials and methods: The disk diffusion, minimum inhibitory concentration and the minimum bactericidal concentration tests were used to check the antimicrobial effect. Ampicillin and Erythromycin discs were used for positive control and sterile physiological serum was used for negative control. Data were analyzed using analysis of variance (ANOVA) and Bonferroni post hoc test.
Results: In disk diffusion test, cinnamon along with fluoride varnish (10.0±1.0mm) caused a significant increase in the diameter of the growth inhibition halo of L. acidophilus (P<0.001), However, the largest growth inhibition halo diameters in L. acidophilus and S. mutans were associated with garlic-cinnamon-varnish (12.0±1.58mm) and fluoride varnish (9.0±0.71mm), respectively. In both strains, the antimicrobial effect of garlic extract was significantly lower than other compounds (P<0.001). The most inhibitory and bactericidal effects were associated with fluoride varnish seen in S. mutans.
Conclusion: According to this study, cinnamon and fluoride varnish has a synergistic antimicrobial effect against L. acidophilus in laboratory conditions. Also, cinnamon extract due to similar effects to fluoride varnish, can be useful as an alternative agent in controlling and preventing dental caries.
 

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Background and purpose: Fluoride varnish application is a successful approach in preventative dentistry. Considering the antimicrobial capabilities of Grape Seed Extract (GSE) and its impact on tooth re-mineralization, the current study was conducted to comparre the effect of this extract, with and without fluoride varnish, as well as their synergistic effects on the caries-causing bacteria Streptococcus mutans and Lactobacillus acidophilus.
Materials and methods: In the current laboratory-analytical study, the disk agar diffusion (growth inhibition halo) and microbroth dilution tests were used to investigate the antibacterial properties and minimum inhibitory concentration (MIC) of the compounds. Ampicillin and Erythromycin discs were utilized for positive control, and sterile physiological serum was used for negative control. The collected data was analyzed using SPSS software (version 16) and analysis of variance (ANOVA), Kruskal-Wallis, U-Man-Whitney, and independent t-tests.
Results: The largest diameter of the growth inhibition halos in S. mutans and L. acidophilus were found in 2.5 mg/ml varnish (12.0±0.7 mm) and 5 mg/ml GSE (13.6±1.1 mm), respectively. Moreover, the smallest halo diameter was recorded in 2.5 mg/ml GSE (7.0±0.9 mm) and the combination of the two extracts at 2.5 mg/ml concentration (5.6±0.9 mm), respectively. Varnish had the lowest MIC in both bacterial species tested (1.8±0.7 mg/ml), and there was no evidence of a synergistic interaction between the two compounds; however, GSE performed comparatively similar to varnish at a dosage of 5 mg/ml.
Conclusion: Based on the findings of the present study, GSE can be considered an acceptable alternative to fluoride varnish in the early phases of dental caries treatment and prevention.
 

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Background and purpose: The antibacterial properties of pomegranate have been investigated in numerous studies. The aim of this study was to compare the antimicrobial effect of pomegranate seed extract (PSE) with Minnimally Invasive (MI) fluoride varnish and also to investigate their synergistic effect on the caries-causing bacteria Streptococcus mutans and Lactobacillus acidophilus bacteria.
Materials and methods: In this in-vitro study, the antibacterial properties and the minimum inhibitory and bactericidal concentrations (MIC and MBC, respectively) of the the compounds were investigated using the disk agar diffusion test (growth inhibition halo) and the micro broth dilution test. The antibacterial activity of the methanolic extracts was studied in 5 groups: PSE, PSE and varnish, MI varnish, positive control (ampicillin and erythromycin) and negative control (sterile physiological serum). The data were analyzed using SPSS ver22 software.
Results: The largest diameter of growth inhibition in S. mutans and L. acidophilus was observed in the combination of two extracts (12±0.22mm) and varnish (12±1.22mm), respectively, while the smallest diameters were recorded in PSE (8.0±1.0mm and 4.0±1.5mm, respectively). Varnish showed the lowest MICs and MBCs for both types of bacteria tested. PSE and varnish showed similar results in inhibiting the growth of S. mutans (P=0.588); however, the simultaneous use of two extracts showed significant synergistic effects (P<0.05).
Conclusion: The MI varnish has a more favorable effect than the other groups studied, and a lower concentration is required to inhibit the growth of two bacterial species. However, high concentrations of PSE, with and without fluoride varnish, can be used against Streptococcus mutans.

 

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 Background and purpose: Gingivitis is an inflammatory disease of the gums caused by accumulation of dental plaque. It can become a chronic periodontal disease if plaque spread below the gum line. The most common pathogens that contribute to periodontal disease include Streptococcus mutans, Streptococcus pyogenes, and Candida albicans. Due to the side effects of common treatment by chlorhexidine mouthwash, novel treatments to fight such microbes are much of interest. This study aimed at comparing the antimicrobial effect of herbal mouthwash containing the extracts of nut-grass and thyme and chlorhexidine mouthwash on common periodontal pathogens.
Materials and methods: First, Cyperus rotundus and Thymus vulgaris were collected, powdered, and the hydro alcoholic extract of the mixture of two plants and the methanol extract of each plant were taken. Then, a mouthwash containing combined extract of the two plants was prepared using different exipients. To evaluate the antimicrobial effect of the extracts, S. mutans, S. pyogenes, and C. albicans were used. After determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the effect of mouthwash on S. mutans biofilm formation and degradation was investigated.
Results: The MIC of the mouthwash formulation against S. mutans, S. pyogenes, and C. albicans were 0.625, 0.039, and 2.5 mg/ml, respectively. The MBC of the mouthwash for each microorganism was 1.25, 0.078, and 10 mg/ml, respectively. The herbal mouthwash significantly inhibited biofilm formation compared to the positive control (P<0.05) which showed no significant difference compared to the negative control (P>0.05). Findings showed no significant difference in biofilm destruction between the herbal mouthwash and the positive control (P>0.05).
Conclusion: The prepared herbal mouthwash showed significant antimicrobial and anti-biofilm effects, and was much more effective in preventing biofilm formation than the standard treatment by chlorhexidine.