Efficacy of Solution Form of Ethylenediaminetetraacetic Acid on Removing Smear Layer of Root Canal at Different Exposure Time In Vitro

Summary： This study was aimed to evaluate the effectiveness of solution form of 17% ethylenediaminetetraacetic acid （EDTA） on removing smear layer of root canals at different exposure time periods and to provide scientific basis for EDTA as a choice of root canal irrigation in clinical practice. Twenty-five single-rooted teeth were randomly divided into 5 groups： control group （group A） was given 2.5% NaOC1, and 4 experimental groups were given 2.5% NaOC1 and 17% EDTA, including groups B, C, D and E with exposure time of 1, 3, 5 and 7 min, respectively. After preparation of the root canals, the teeth were split along their longitudinal axis, and the root sections were examined under scanning elec- tron microscope for evaluation of smear layer removal and erosion on the surface of the root canal walls. The specimens in group B showed presence of smear layer on the walls of the root canal with no statistical difference from that in group A （P〉0.05）. In groups C and D, partial removal of smear layer was obtained, and there was no significant difference between the two groups （P〉0.05）, but there was significant difference in removal of smear layer between group C and group B （P〈0.05）. Root canal walls in group E specimens showed almost complete removal of smear layer, and the removal of smear layer was significantly different from that in group D （P〈0.01）. There was no significant change in the structure of the surface of root canal for each sample. It was concluded that combined irrigation with 17% EDTA and 2.5% NaOC1 could remove the smear layer with no significant alteration in dentinal structure when the chelating agent was applied for 7 min. At 3 and 5 min of application, partial removal of smear layer was observed and at 1 min negligible removal of smear layer was achieved.

Synthesis and Crystal Structure of a New Cadmium(Ⅱ) Coordination Polymer with Ethylenediaminetetraacetic Acid

A new cadmium（Ⅱ） coordination polymer,namely,[KCd2（edta）I]n（1,H4edta = ethylenediaminetetraacetic acid）,has been prepared and structurally characterized by single-crystal X-ray diffraction.Crystallographic data for 1：C10H12Cd2IKN2O8,Mr = 679.02,monoclinic,space group P21/n,a = 9.870（5）,b = 8.989（4）,c = 19.082（10） ,β = 104.581（10）o,V = 1638.5（13） 3,Z = 4,Dc = 2.753 g/cm3,μ = 4.776 mm-1,F（000） = 1272,the final R = 0.0473 and wR = 0.1311 for 2846 observed reflections with I 〉 2σ（I）.Polymer 1 features a 2-D layered structure,in which each edta4-ligand chelates/bridges five adjacent six-/seven-coordinated Cd（Ⅱ） centers with all ten donors（eight oxygen and two nitrogen） involved with coordination.Additional iodide I-ions as counterions are bound to the Cd（Ⅱ） centers in a terminal mode and the potassium K＋ ions are located in the layers and surrounded by O and I atoms from neighboring environment.The thermal stability of 1 has been discussed.

Ethylenediaminetetraacetic acid-assisted synthesis of Bi2Se3 nanostructures with unique edge sites

Nanomaterials with unique edge sites have received increasing attention due to their superior performance in various applications. Herein, we employed an effective ethylenediaminetetraacetic acid (EDTA)-assisted method to synthesize a series of exotic Bi2Se3nanostructures with distinct edge sites. It was found that the products changed from smooth nanoplates to half-plate-containing and crown-like nanoplates upon increasing the molar ratio of EDTA to Bi3+. Mechanistic studies indicated that, when a dislocation source and relatively high supersaturation exist, the step edges in the initially formed seeds can serve as supporting sites for the growth of epilayers, leading to the formation of half-plate-containing nanoplates. In contrast, when the dislocation source and a suitably low supersaturation are simultaneously present in the system, the dislocation-driven growth mode dominates the process, in which the step edges form at the later stage of the growth responsible for the formation of crown-like nanoplates. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

A Comparative Study on the Enhancement Efficacy of Specific and Non-specific Iron Chelators for Protoporphyrin Ⅸ Production and Photosensitization in HaCat Cells

The iron chelators can be utilized in target cells to improve 5-aminolaevulinic acid （ALA）-based photodynamic therapy （PDT）. The purpose of this study is to compare the effect of two kinds of iron chelators, desferrioxamine （DFO） and ethylenediaminetetraacetic acid （EDTA） on the enhancement of ALA-PDT. HaCat cells were cultured in medium containing 2.0 mmol/L of ALA and 0.5 mmol/L of DFO or EDTA. After 3-h incubation in the dark, the concentration of cellular pro-toporphyrin Ⅸ （PpⅨ） was detected by high performance liquid chromatography （HPLC）, and the fluorescence of PpⅨ was observed at 630 nm emission under confocal laser scanning microscope. For PDT, HaCat cells were irradiated using 632.8 nm laser, and the fractions of apoptotic and necrotic cells were flow cytometrically assayed. Related differences in morphology and ultrastructure of Ha-Cat cells were observed using optical microscope or transmission electron microscope. Compared to incubation with ALA alone, the addition of DFO or EDTA increased the concentration of cellular PpⅨ and the fluorescent density of PpⅨ, and also increased cell death ratio after PDT. PDT using ALA plus DFO produced the highest cellular PpⅨ level, greatest cell death ratio and most severe structural damage to the cells. It was concluded that both DFO and EDTA could enhance ALA-based PpⅨ production and PDT. Compared to the non-specific iron chelator of EDTA, the specific chelator, DFO, showed more potential for the enhancement.

Investigation on the Coordinate Structures of the Rare Earth Metal Complexes with Edta and Cydta Ligands

The crystal and molecular structures of cydta (trans-1, 2-cyclohexanediaminetetraacetic acid) have been determined by single\|crystal X-ray structure analyses. The reasons that RE Ⅲ -edta and RE Ⅲ -cydta complexes select different coordinate structures were discussed and illustrated through the comparison of the molecular and crystal structures between edta and cydta, (NH_ 4 )\[Y Ⅲ (edta)(H_ 2 O)_ 3 \]\55H_ 2 O and (NH_ 4 )\[Y Ⅲ (cydta)(H_ 2 O)_ 2 \]\55H_ 2 O as well as (NH_ 4 )\[Gd Ⅲ (edta)(H_ 2 O)_ 3 \]\55H_ 2 O and (NH_ 4 )\[Gd Ⅲ (cydta) (H_ 2 O) _ 2 \]\55H_ 2 O complexes.

Syntheses and Structure of Nine-Coordinate Gd~Ⅲ Complexes,Na[Gd~Ⅲ(edta)(H_2O)_3]·5H_2O and Na_4[Gd~Ⅲ(dtpa)(H_2O)]_2·14H_2O

The crystal and molecular structures of the Na[Gd Ⅲ(edta)(H_2O)_3]·5H_2O (edta=ethylenediaminetetraacetic acid) and Na_4[Gd Ⅲ(dtpa)(H_2O)]_2·14H_2O (dtpa=diethylenetriaminepentaacetic acid) complexes were determined by single-crystal X-ray structure analyses. The crystal of the Na[Gd Ⅲ(edta)(H_2O)_3]·5H_2O belongs to orthorhombic crystal system and Fdd2 space group. The crystal data are as follows: a =1.9424(7)nm,b =3.5496(12)nm,c =1.2125(4)nm,V =8.360(5)nm 3,Z =16,M =612.63,D _c=1.947 g·cm (-3),μ =3.274 mm (-1) and F (000)=4880. The final R and wR values are 0.0295 and 0.0677 for 3102 [ I>2.0σ(I) ] unique reflections,and 0.0328 and 0.0695 for all 8269 reflections,respectively. The [Gd Ⅲ(edta)(H_2O)_3]-complex anion has a nine-coordinate pseudo-monocapped square antiprismatic structure in which the nine coordinate atoms,two N and seven O are from one edta ligand and three coordinate water molecules. The crystal of the Na_4[Gd Ⅲ(dtpa)(H_2O)]_2·14H_2O belongs to monoclinic crystal system and P2(1)/n space group. The crystal data are as follows: a =1.4894(6)nm,b =1.7987(7)nm, c =1.9600(7)nm,β =99.496(7),V =5.179(3)nm3,Z=4,M =1471.44,D _c=1.841 g·cm (-3),μ =2.676 mm (-1) and F (000)=2872. The final R and wR are 0.0435 and 0.0979 for 8929 [ I>2.0σ(I) ] unique reflections,and 0.0820 and 0.1167 for all 20717 reflections,respectively. The total complex moleculue is composed of two close parts in structure. The [Gd Ⅲ(dtpa)(H_2O)] (2-) complex anion in the every part has a nine-coordinate structure with distorted monocapped square antiprismatic prism,in which the dtpa coordinates with central Gd Ⅲ ion acting as a octadentate ligand with three N atoms and five O atoms,and one water as the ninth ligand directly coordinates with central Gd Ⅲ ion.

Evaluation of Disk Potentiation Test (DPT) and Double Disk Synergy Test (DDST) for The Detection of Metallo-β-Lactamases (MBLs) in Clinical Isolates of Bangladesh

Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.

Chromium Extraction from Sewage Sludge Using Polyepoxysuccinic Acid

An environmentally benign biodegradable chelant,polyepoxysuccinic acid(PESA),was used to separate heavy metals from sewage sludge from the Shanghai Taopu Wastewater Treatment Plant,China,based on chemical extraction technology.The extraction of chromium(Cr) from sewage sludge with an aqueous solution of PESA was studied under various conditions.It was found that the extraction of Cr using PESA was more efficient than that using ethylenediaminetetraacetic acid(EDTA) and S,S-ethylenediaminedisuccinic acid(EDDS) under similar conditions.PESA was capable of extracting Cr from the sewage sludge,and the extraction efficiency was obviously dependent on both the pH and the concentration of the chelating reagent.The extraction efficiency decreased gradually with increasing pH,and the dependence on pH decreased as the concentration of PESA increased.The extraction efficiency reached 58% under conditions of pH = 4 and a ratio of PESA to total heavy metals of 10:1.The extraction efficiency was maintained above 40% within the pH range from 1 to 7 at the high ratio of PESA to total heavy metals of 10:1.Comparing the contents of heavy metals in the sewage sludge before and after the extraction,it was found that the extracted Cr came mainly from the reducible and oxidizable fractions.

Lead Induced Changes in the Growth and Antioxidant Metabolism of the Lead Accumulating and Non-accumulating Ecotypes of Sedum alfredii

The phytotoxicity and antioxidative adaptations of lead （Pb） accumulating ecotype （AE） and non-accumulating ecotype （NAE） of Sedum alfredii Hance were investigated under different Pb treatments involving 0, 0.02 mmol/L Pb, 0.1 mmol/L Pb and 0.1 mmol/L Pb/0.1 mmol/L ethylenediaminetetraacetic acid （EDTA） for 6days. With the increasing Pb level, the Pb concentration in the shoots of AE plants enhanced accordingly, and EDTA supply helped 51% of Pb translocation to shoots of AE compared with those treated with 0.1 mmol/L Pb alone. Moreover, the presence of EDTA alleviated Pb phytotoxicity through changes in plant biomass, root morphology and chlorophyll contents. Lead toxicity induced hydrogen peroxide （H2O2） accumulation and lipid peroxidation in both ecotypes of S. alfredii. The activities of superoxide dismutase （SOD）, guaiacol peroxidase （G-POD）, ascorbate peroxidase, and dehydroascorbate reductase elevated in both leaves and roots of AE as well as in leaves of NAE with the increasing Pb levels, but SOD and G-POD declined in roots of NAE. Enhancement in glutathione reductase activity was only detected in roots of NAE while a depression in catalase activity was recorded in the leaves of NAE. A significant enhancement in glutathione and ascorbic acid （AsA） levels occurred in both ecotypes exposed to Pb and Pb/EDTA treatment compared with the control, however, the differences between these two treatments were insignificant. The dehydroascorbate （DHA） contents in roots of both ecotypes were 1.41 to 11.22-fold higher than those in leaves, whereas the ratios of AsA to DHA （1.38 to 6.84） in leaves altering more to the reduced AsA form were much higher than those in roots. These results suggested that antioxidative enzymes and antioxidants play an important role in counteracting Pb stress in S. alfredii.

Influence of EDTA on Demineralization Rate of Dentine:Calcification Treatment in Root Canal Therapy

The aim of this study was to investigate the influence of ethylenediaminetetraacetic acid （EDTA） irrigation on demineralization rate of dentine located in the apical third of root canal walls. Teeth were divided into A and B two groups. In group A, all of the teeth was irrigated with EDTA and NaOCI （sodium hypochlorite）, followed by cutting the apical third into slices longitudinally to examine the influence of EDTA on different portions of apical third of root canal. In group B, the apical third of a tooth was firstly cut into slices longitudinally, followed by coating the root canal walls with EDTA to in-situ observe the demineralization of dentine with different time. It was found that the influence of EDTA on root-canal was gradually increased from the apical to the upper end of the apical third for group A. In addition, the demineralization rate of dentine was remarkable in the first 25 min for group B. The diffusion of EDTA into root dentine would lead to potential damage to the dentine. Furthermore, demineralization rate curve was calculated.

Influence of casein phosphopeptide-amorphous calcium phosphate application,smear layer removal, and storage time on resin-dentin bonding

The aim of this study is to evaluate the influence of Tooth Mousse （TM） application, smear layer removal, and storage time on resin-dentin microtensile bond strength （pTBS）. Dentin specimens were divided into two groups： （1） smear layer covered; （2） smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were treated once with TM for 60 min. After bonding procedures using a two-step self-etching adhesive （Clearfil SE Bond （CSE）; Kuraray Medical, Tokyo, Japan）, an all-in-one adhesive （G-Bond （GB）; GC Corp, Tokyo, Japan）, and a total-etch adhesive （Adper Single Bond 2 （SB）; 3M ESPE, St. Paul, MN, USA）, the specimens were stored for 3 d or 6 months in deionized water at 37 ℃, and pTBS was tested and analyzed. With the exception of SB （no TM application） and GB, the pTBS was significantly increased for CSE and SB using EDTA pre-conditioning and 3 d of storage （P≤0.001）. Bond strength of GB decreased significantly when using EDTA （3 d storage, P〈0.05）. TM application only increased the pTBS of GB （no EDTA） and SB （with EDTA） after 3 d （P≤0.02）. Comparing the adhesives after 3 d of storage, CSE exhibited the greatest pTBS values followed by GB and SB （P≤0.02）. The factors of adhesive, EDTA, and TM did not show any significant impact on pTBS when specimens were stored for 6 months （P〉0.05）. The additional application of TM and EDTA for cavity preparation seems only to have a short-term effect, and no influence on pTBS of dentin bonds after a period of 6 months.