Antimicrobial activity, toxicity and accumulated hard-tissue debris (AHTD) removal efficacy of several chelating agents.

AIM: To evaluate the antimicrobial, toxicity and cleaning effectiveness of ethylenediaminetetraacetic acid (EDTA) and maleic acid (MA) alone and combined with cetrimide (CTR). METHODOLOGY: Cytotoxic and genotoxic effects were assessed on Chinese hamster cells V79 using the MTT, clonogenic and micronucleus assays, respectively. The bacterial inhibitory and bactericidal concentrations (MIC and MBC, respectively) were determined on a strain of Enterococcus faecalis. Antimicrobial tests were performed on a biofilm model after treatment with the chelating agents by using a biofilm eradication concentration (MBEC) and confocal laser scanning microscope (CLSM) assays. Quantification of cell biomass and percentage of live and dead cells in the biomass were assessed for each group. The percentage reduction of accumulated hard-tissue debris (AHTD) after root canal preparation and final irrigation protocols was evaluated by micro-CT. Statistical tests of one-way analysis of variance (anova), Bonferroni test, Kruskal-Wallis test, Dunn's multiple comparison test and Wilcoxon matched-pairs signed-rank tests were used. RESULTS: Cetrimide alone as well as in combination with EDTA and MA at dilutions of 1/10 and 1/100 was significantly more toxic as compared to untreated controls (P < 0.001). All tested mixtures were nontoxic at a dilution of 1/1000. EDTA retained a weak inhibitory and bactericidal effect against planktonic cells, whilst MA inhibited cells growth and killed 99.9% of the cells when diluted. CTR revealed the most prominent effect, being inhibitory and bactericidal, also when diluted. Cetrimide alone or combined with EDTA was able to remove, respectively, 40% (P < 0.01) and 60% (P < 0.001) of the entire biomass after 1 min. Conversely, MA alone and in combination with CTR did not have a significant effect on biomass reduction. After final irrigation, the AHTD volume was significantly decreased in all groups (P < 0.05). EDTA + CTR and MA + CTR were associated with a significant reduction in the percentage of AHTD on the entire root canal compared to the same solutions without surfactant. CONCLUSIONS: 7% MA was less cytotoxic in comparison with 17% EDTA. The addition of cetrimide to EDTA and MA removed accumulated hard-tissue debris effectively from the canal walls and increased their antimicrobial activity when compared to the same solutions without detergents.

Chemical, cytotoxic and genotoxic analysis of etidronate in sodium hypochlorite solution.

AIM: To test whether the incorporation of a chelation powder, etidronate, marketed for root canal irrigation (Dual Rinse HEDP) into a sodium hypochlorite (NaOCl) solution induced additional cytotoxic and genotoxic effects not observed with NaOCl alone. METHODOLOGY: Fresh and 24-h-old mixtures of 0.9 g of etidronate in 10 mL of 2.5% NaOCl were assessed for their basic chemical features including pH and the ability to chelate Ca2+ from hydroxylapatite. Pure NaOCl and phosphate-buffered saline (PBS) with/without etidronate served as control solutions. Cytotoxic and genotoxic effects of diluted solutions (1:10, 1:100, and 1:1000) were assessed on Chinese hamster lung fibroblast (V79) using the MTT, clonogenic and micronucleus assays, respectively. One-way ANOVA and Tukey's HSD test were applied with an alpha-type error of 5% (P < 0.05). RESULTS: In mixtures of NaOCl and etidronate, the free available chlorine was lost completely after 24 h, and the pH dropped by more than 3 units. However, the ability of the etidronate to chelate Ca2+ was maintained. The fresh mixtures of NaOCl and etidronate were not more toxic than NaOCl alone (P > 0.05), whilst the 24-h-old mixtures were less toxic (P < 0.05) and statistically similar to pure etidronate. Etidronate per se showed little cytotoxicity and no genotoxicity at the tested dilutions. CONCLUSIONS: The ability of the used etidronate, Dual Rinse HEDP, to chelate calcium is not affected by NaOCl. Cytotoxicity and genotoxicity of mixed solutions is dictated by the presence of free available chlorine therein.

Evaluation and optimization of radioprotective activity of Coronopus didymus Linn. in gamma-irradiated mice.

PURPOSE: To evaluate and optimize the radioprotective ability of the most potent fraction of an aqueous extract of Coronopus didymus in whole body gamma-irradiated Swiss albino mice and to evaluate the antioxidant status and lipid peroxidation of the livers of the surviving mice. To correlate the free radical scavenging studies with in vivo radioprotection ability. MATERIALS AND METHODS: Swiss albino mice were treated with either vehicle or the different doses of extract/fraction suspension by an i.p. route, 30 min before exposure to 10 Gy gamma-irradiation and the animals were monitored twice daily for any signs of radiation toxicity and mortality. Radiation dose response (7-11 Gy), optimization of route, time of drug administration and evaluation of dose response factor (DRF) at the best dose of the fraction was studied. Endogenous antioxidant status and lipid peroxidation of the livers of the mice surviving on the 31st day was evaluated by using spectrophotometric methods. RESULTS: The most active free radical scavenging fraction (CDF1) as assessed by competition kinetic studies using pulse radiolysis showed maximum in vivo radioprotection of 70% at a dose of 400 mg/kg body weight (bw) compared to corresponding 10 Gy irradiated control. Optimum radioprotection was observed upon i.p. administration, 30 min prior to 10 Gy irradiation and DRF at a dose of 400 mg/kg bw for 30 day survival was found to be 1.07. The levels of endogenous antioxidant enzymes and lipid peroxidation in the CDF1 treated surviving mice were found to reverse back to their normal levels. CONCLUSIONS: The optimum dose, time and route of drug administration for maximum radioprotection by CDF1 were determined. The reversal of the levels of endogenous antioxidant enzymes and lipid peroxidation indicates reduced oxidative stress in CDF1 treated surviving mice.

Preventive efficacy of hydroalcoholic extract of Cymbopogon citratus against radiation-induced DNA damage on V79 cells and free radical scavenging ability against radicals generated in vitro.

This study presents the findings of free radical scavenging and antigenotoxic effect of hydroalcoholic extract of Cymbopogon citratus (CCE). The CCE at a concentration of 60 microg/mL resulted in a significant scavenging ability of 2,2-diphenyl-2-picryl hydrazyl (DPPH; (85%), 2,2-azinobis (3-ethyl benzothiazoline-6-sulphonic acid) (ABTS; 77%), hydroxyl (70%), superoxide (76%), nitric oxide (78%) free radicals generated using in vitro and also a moderate anti-lipid peroxidative effect (57%). Further, the radiation-induced antigenotoxic potential of CCE was assessed in Chinese hamster lung fibroblast cells (V79) using micronucleus assay. The CCE resulted in a dose-dependent decrease in the yield of radiation-induced micronuclei, with a maximum effect at 125 microg/mL CCE for 1 h before 2 Gy of radiation. Similarly, there was a significant (P < 0.05-0.0001) decrease in percentage of micronuclei when V79 cells were treated with optimal dose of CCE (125 microg/mL) before exposure to different doses of gamma radiation, that is, 0.5-4 Gy, compared with radiation alone groups. The results of the micronucleus study indicated antigenotoxic effect demonstrating the radioprotective potential of CCE and, which may partly due to its and antioxidant capacity as it presented its ability to scavenge various free radicals in vitro and anti-lipid peroxidative potential.

The effect of high energy mechanochemical processing on the microstructure, piezoelectric, ferroelectric and mechanical properties of PLZT ceramics.

Lead lanthanum zirconate titanate (PLZT) ceramics were synthesized using a high energy mechanochemical processing technique, using tungsten carbide grinding vials and balls. The ceramic powders were prepared using the constituent oxide powders, which were subjected to high energy milling, without the use of any excess PbO in the starting composition. TEM studies revealed the formation of very fine particles of the order of 30 nm, due to the milling effect. Highly dense ceramics could be prepared via sintering which resulted in ultra-high strains in these piezoelectric samples of up to 0.25%, a value which has not been reported hitherto by any other known process. The effect of the reduction in particle size on the microstructure, mechanical and electrical properties of PLZT ceramics were studied and are discussed herein.