Evaluation of Antimicrobial Activity of A Fast-Setting Bioceramic Endodontic Material

Background: To evaluate the antimicrobial activity of the fast-setting bioceramic iRoot Fast Set Root Repair Material (iRoot FS) and two other calcium silicate cements. Methods: The antimicrobial activity of iRoot FS, ProRoot MTA and Biodentine against E. faecalis and P. gingivalis were evaluated in this study. The materials were freshly mixed or set for 1 and 7 days on 5mm diameter sterile filter papers. The agar diffusion test, direct contact test and carry-over effect test were conducted, and the pH values (using a digital pH meter) were also evaluated. The data were analyzed by an analysis of variance and two-way ANOVA (α=0.05).Results: In the agar diffusion experiment, no obvious inhibition zone was observed for iRoot FS, ProRootMTA or Biodentine at any time interval. In the direct contact test, all three materials showed good antibacterial activity after setting for 20 minutes. The antibacterial properties of the three materials decreased with the increase of setting time. None of the three materials showed carry-over antibacterial effect. The pH measurement showed that the suspension of all the three materials showed high pH values (11-12). With the extension of setting time, the pH of iRoot FS and Biodentine slightly decreased.Conclusions: Fresh iRoot FS, Biodentine, and MTA killed E. faecalis and P. gingivalis effectively, and the antimicrobial effect of all the three materials decreased over 1 and 7 days after mixing. All three materials showed a tendency of alkalinity which last for at least 7 days after setting.

Antimicrobial and cytotoxic capacity of pyroligneous extracts films of Eucalyptus grandis and chitosan for oral applications

Chitosan films containing distilled pyroligneous extracts of Eucalyptus grandis (DPEC), characterized and developed by Brazilian Agricultural Research Corporation—Embrapa Temperate Agriculture (EMBRAPA-CPACT), were evaluated for antimicrobial activity against Candida albicans, Streptococcus mutans, and Lactobacillus acidophilus by direct contact test. Further, their capacity for the prevention of teeth enamel demineralization and cytotoxicity in vitro were also determined. The natural polymers were tested at different concentrations (1500–7500 µg mL−1) and the formulation of an experimental fluoride varnish with antimicrobial activity was evaluated by direct contact test, whereas cytotoxicity was analyzed through the colorimetric MTT assay. Preliminary data showed no statistically significant differences in cytotoxicity to NIH/3T3 cell line when DPEC is compared to the control group. On the other hand, the antimicrobial capacity and demineralization effects were found between the test groups at the different concentrations tested. Chitosan films containing distilled pyroligneous extracts of E. grandis may be an effective control strategy to prevent biofilm formation related to dental caries when applied as a protective varnish. They may inhibit the colonization of oral microorganisms and possibly control dental caries through a decrease in pH and impairment of enamel demineralization.

Low-temperature flow-synthesis-assisted urethane-grafted zinc oxide-based dental composites: physical, mechanical, and antibacterial responses

A novel way was adopted to graft zinc oxide (ZnO) with urethane-modified dimethacrylate (UDMA) in order to utilize them as reinforcing agents in resin-based dental composites. Experimental novel composites were synthesized having UDMA-grafted and nongrafted ZnO, at a concentration of 0 wt.%, 5 wt.%, and 10 wt.%. The same concentrations of ZnO were also incorporated in Filtek Z250 XT (3 M ESPE, USA). The antibacterial behavior was evaluated against Streptococcus mutans by direct-contact test at one, three, and seven days of incubation. The compressive strength and Vickers microhardness were tested as per ISO 9917 and ISO/CD6507-1, respectively. For abrasive wear resistance, mass loss and roughness average after tooth-brushing cycles of 24,000 at custom-made tooth-brushing simulator were evaluated using noncontact profilometer. Data analysis was carried out using post hoc Tucky’s test and nonparametric Kruskal–Wallis test. Direct contact test revealed that the antibacterial potential of novel and commercial composites was increased with an increase in the concentration of grafted ZnO as compared with nongrafted, whereby the potential was the highest at day seven. There was a significant decrease in compressive strength and Vickers hardness of commercial composites on addition of grafted ZnO while there was no significant difference in the strength of experimental novel composite. The abrasive wear of commercial and experimental composites was within clinical limits. Low-temperature flow-synthesis method was successfully employed to synthesize grafted and nongrafted ZnO. The UDMA-grafted ZnO can be incorporated into dental composites without decreasing their strength and these composites can be used to combat secondary caries.

Ecotoxicity testing of airborne particulate matter—comparison of sample preparation techniques for the Vibrio fischeri assay

The bioassay based on the bioluminescence inhibition of the marine bacterium Vibrio fischeri has been the most widely used test for the assessment of airborne particulate matter ecotoxicity. Most studies available use an extract of the solid sample, either made with water or organic solvents. As an alternative, a whole-aerosol test is also available where test bacteria are in actual contact with contaminated particles. In our study, different extraction procedures were compared to this direct contact test based on the V. fischeri assay and analytical measurements. The lowest PAH content and the highest EC50 were determined in water extract, while the highest PAH amount and lowest EC50 were measured in dichloromethane, hexane, and dimethyl-sulphoxide extracts. EC50 of the direct contact test was comparable to that of the methanol extract. Our results suggest that the sensitivity of the direct contact test equals to that of extraction procedures using organic solvents, moreover, it is mimicking an environmentally realistic exposure route.

Evaluation of Antimicrobial Efficacy of Pudina (Menthaarvenis), Tulsi (Ocimumtenuiflorum) and Curry Leaves (Murrayakoenigii) on Streptococcus mutans by Modified Direct Contact Test- An In vitro Study

Introduction: Dental caries is a pandemic disease caused by Streptococcus mutans. Numerous preventive strategies have been developed to prevent dental caries with modern medicines. Recently, there has been a shift from use of modern medicines to herbal ayurvedic preparations which are easily available and cause least possible side effects but have not been tested against S. mutans. Aim: To evaluate antimicrobial value of Pudina, Tulsi and Curry leaves against S. mutans by modified direct contact test. Materials and Methods: This in vitro study used finely powdered form of Pudina, Tulsi and Curry leaves extracts (Hakim Chi Chi Pharmacy, Surat, India) without any added preservatives. The test microorganism S. mutans was isolated from human saliva using mitis salivarius agar. The Minimum Inhibition Concentration (MIC) was determined using agar well diffusion for Group 1 (Tulsi), Group 2 (Pudina), Group 3 (Curry leaves) and Group 4 (Chlorhexidine). Using this MIC, modified Direct Contact Test was performed for specific evaluation of the antimicrobial efficacy of each product. Chlorhexidine (0.2%) was used as a positive control for the comparison of each product. The results of modified direct contact test were subjected to ANOVA Test and Tukey’s Test using SPSS software version 23.0 which showed that when compared against chlorhexidine, the antimicrobial efficacy against S. mutans in decreasing order was of curry leaves, tulsi and pudina and the result of the study was significant. Results: Curry leaves showed higher antimicrobial efficacy than tulsi and pudina when compared against chlorhexidine (control) and the results were statistically significant (p<0.05). Conclusion: Curry leaf extract shows promising antimicrobial property against S. mutans and can be recommended for caries control with further investigations.

Evaluation of Antibacterial Effect of Silver Nanoparticle Coated Stainless Steel Band Material – An In vitro Study

Correction: On 23rd April 2020, corrections were made to page 16: The caption of Figure 6 (p.16) was changed FROM Figure 4: Petridishes showing Lactobacillus colonies of control samples at (a) 24 hours, (b) 48 hours and (c) 1 week TO Figure 6: Petridishes showing streptococcus mutans colonies of control group at (a) 24 hours, (b) 48 hours and (c) 1 week. The caption of Figure 7 (p.16) was changed FROM Figure 5: Petridishes showing Lactobacillus colonies of test samples at (a) 24 hours, (b) 48 hours and (c) 1 week TO Figure 7: Petridishes showing Streptococcus mutans colonies of test samples at (a) 24 hours (b) 48 hours and (c) 1 week. AbstractIntroduction: Decalcification, caries, inflammatory periodontal disease are the most common iatrogenic effects of orthodontic treatment because of failure to maintain proper oral hygiene. Although various methods have been tried to minimize the incidence of white spot lesions, none of them proved to be effective. The purpose of this study was to develop a hard coating of silver nanoparticles on stainless steel band material and to evaluate the antibacterial efficacy against most common cariogenic pathogens. Materials & Method: Stainless steel band material was cut into 45 pieces of about 0.5 x 1 cm in dimension, of these 25 band material strips were coated with silver nanoparticles using thermal evaporation technology in a Vacuum coating unit (Indovision, India) at a vacuum of 4.5 ×10−5 millibar at 961°C for 5 minutes and remaining strips served as control. Scanning electron microscopy (SEM) study of coated band material showed a uniform deposition of silver nanoparticles of about 18.63 percent by weight. Five coated and five uncoated band material strips were utilized for each test to evaluate the antibacterial effect of the coated band material against Streptococcus mutans, Lactobacillus acidophilus using zone of inhibition and direct contact test. In zone of inhibition test, the bacterial growth inhibition zone was measured after a period of 24-48 hours, where as in direct contact test, the number of bacterial colonies were counted after 24 hours, 48 hours and 1 week. Five coated band materials were immersed separately in a container having 5 ml of artificial saliva and the amount of silver nanoparticles released from coated samples was evaluated after 24 hrs, 48 hrs, and 1 week using atomic absorption spectrophotometer. Result: A stable uniform coating of silver nanoparticles on the band material was obtained by physical vapor deposition. The coated band material showed a potent antibacterial activity against L.acidophilus and S.mutans. The maximum amount of silver nanoparticles released from the silver nanoparticle coated band material was 0.0236 ± 0.0067 ppm, which is below the maximum permissible level set by WHO [0.1 mg /l], proving it as biocompatible. Conclusion: Silver nanoparticle coating on orthodontic band surfaces can provide suitable antimicrobial activity during active orthodontic treatment.

ANTIMICROBIAL ACTIVITY OF MINERAL TRIOXIDE AGGREGATE AND CALCIUM HYDROXIDE SEALER ON ENTEROCOCCUS FAECALIS STRAIN ATCC29212

Objective: The objective of this study was to evaluate the antimicrobial activity of mineral trioxide aggregate (MTA) and calcium hydroxide (Ca(OH)2)sealers on Enterococcus faecalis at various time points after the preparation of the sealer.Methods: Antimicrobial activity of MTA and Ca(OH)2 sealer on E. faecalis (ATCC 29212) was assessed by the direct contact test immediately, 1 day,and 7 days after the preparation of the sealer.Results: The antimicrobial effect of MTA sealer was greatest 1 and 7 days after the preparation of the sealer. The effect of Ca(OH)2 was greatest 1 dayafter the preparation of the sealer.Conclusion: MTA sealer showed constant antimicrobial activity on E. faecalis overtime. By contrast, Ca(OH)2 sealer showed decreasing antimicrobialactivity overtime, with the greatest antimicrobial activity being 1 day after the preparation of the sealer.