Comparison of the Biocidal Efficacy of Sodium Dichloroisocyanurate and Calcium Hydroxide as Intracanal Medicaments over a 7-Day Contact Time: An Ex Vivo Study.

INTRODUCTION: The use of medicaments has been recommended for the treatment of root canal infection. This study evaluated the antimicrobial effect of a well-known biocidal agent, sodium dichloroisocyanurate (NaDCC), by comparing it with calcium hydroxide [Ca(OH)2] using an engineered 3-species biofilm root canal model. METHODS: Thirty-eight human single-rooted teeth were decoronated and chemomechanically prepared before inoculation using Enterococcus faecalis, Actinomyces viscosus, and Streptococcus mutans using a flow cell model for 4 weeks for biofilm formation. The samples were randomly divided into 3 groups: NaDCC (n = 12), Ca(OH)2 (n = 12), and positive control (no medicament, n = 14). The medicaments were placed using a Lentulo spiral. After a contact time of 7 days, the roots were crushed and plated on selective media. Bacterial identities were confirmed with the use of selective media. Colony-forming units were calculated (CFU/ml). Descriptive statistics (mean and standard deviations) were calculated. RESULTS: Seven-day dressing with NaDCC or Ca(OH)2 presented with no growth. For the positive control, the mean colony-forming units were 2.97E4 ± 3.42E4 (CFU/ml). All previously inoculated strains were recovered in the control group. CONCLUSIONS: NaDCC and Ca(OH)2 when used as intracanal medicaments were able to eradicate an engineered 3-species biofilm in single-rooted teeth in an ex vivo model. NaDCC deserves further investigation as an intracanal medicament.

'Chocolate' silver nanoparticles: Synthesis, antibacterial activity and cytotoxicity.

HYPOTHESIS: Silver nanoparticles (AgNPs) have emerged as a powerful weapon against antibiotic resistant microorganisms. However, most conventional AgNPs syntheses require the use of hazardous chemicals and generate toxic organic waste. Hence, in recent year's, plant derived and biomolecule based synthetics have has gained much attention. Cacao has been used for years for its medicinal benefits and contains a powerful reducing agent - oxalic acid. We hypothesized that, due to the presence of oxalic acid, cacao extract is capable of reducing silver nitrate (AgNO3) to produce AgNPs. EXPERIMENTS: In this study, AgNPs were synthesized by using natural cacao extract as a reducing and stabilizing agent. The reaction temperature, time and reactant molarity were varied to optimize the synthesis yield. FINDINGS: UV-visible spectroscopy (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization demonstrated that the synthesized AgNPs were spherical particles ranging in size from 35 to 42.5nm. The synthesized AgNPs showed significant antibacterial activity against clinically relevant pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis. Importantly, these green AgNPs are not cytotoxic to human dermal fibroblasts (HDFs) at concentrations below 32µg/ml. We conclude that cacao-based synthesis is a reproducible and sustainable method for the generation of stable antimicrobial silver nanoparticles with low cytotoxicity to human cells. The AgNPs synthesized in this work have promising properties for applications in the biomedical field.

Comparison of a novel bilayered medium with the conventional media for cultivation of Mycobacterium tuberculosis.

BACKGROUND & OBJECTIVE: There is resurgence of tuberculosis in recent years in spite of availability of comprehensive multidrug therapy. Conventional culture media require a long time for the appearance of growth of Mycobacterium tuberculosis, while the other methods are expensive. Hence, a rapid low cost and safe bilayered medium was developed for early growth and sensitivity testing of M. tuberculosis and the results were compared with those on Lowenstein Jensen medium, Middlebrook 7H10 and Kirchner's liquid media. METHODS: A specially designed bilayered medium, consisting of a lower layer of Lowenstein Jensen medium without malachite green and a top layer of Middlebrook 7H 10 medium with added antibiotics and antifungal agents was prepared. Sputum from clinically suspected cases of tuberculosis, pleural fluid and pus samples were inoculated on the bilayered medium along with the inoculation on other conventional media after proper decontamination and concentration of the samples. Antibiotic sensitivity pattern was determined against a few rapidly growing control and test strains by disc diffusion technique and the results could be recorded by 3 to 7 days. RESULTS: Statistically significant (P< 0.001) isolation rate was obtained on this bilayered medium when compared with the other three media, being 81.7 per cent growth by 7 days. Antibiotic sensitivity test could be recorded by 3 days in case of the rapidly growing strains on this medium, and by 7 days in case of M. tuberculosis strains. INTERPRETATION & CONCLUSION: Bilayered medium produced rapid growth earliest by 48 h, higher isolation rates were achieved as compared to the other conventional media and drug sensitivity testing could also be carried out successfully. Thus, the bilayered medium can be used for obtaining early culture report.