Effect Of NaOCl Research Articles

Effect of NaOCl on cyclic fatigue resistance.

The impact of 5.25 percent NaOCL on the resistance offered by TruNatomy, Hero Gold and ProtaperGold against cyclic fracture as against the treatment of NiTi rotary files with distilled water is of interest to dentists. Inside the stainless steel blocks, man-made canals were created for the purpose of testing the cyclic fatigue. 60 endodontic files were taken as study specimens. It was observed that values of number of cycles to fracture in NaOCl among three file systems were in the order of TruNatomy (1053.50 ± 134.81)>Hero Gold (652.66 ± 58.66) > ProtaperGold (494.50 ± 47.69). The TruNatomy file system reflected greatest cyclic fatigue resistance. It was also found that cyclic fatigue resistance in NiTi rotary files studied here is not hampered by 5.25% NaOCl.

Effect of NaOCl and ClO2 on seawater desalination using reverse osmosis with cartridge filtration as the pretreatment during the algal bloom

Increased seawater temperature leads to harmful algal blooms (HABs), which releases toxic materials and extracellular polymeric substances (EPS) that are harmful to both humans and the environment. Reverse osmosis (RO) with cartridge filter (CF) as the pretreatment process is often used for desalination process. However, the EPS causes severe fouling on the CF, and RO membrane. Disinfectants, such as NaOCl and ClO2, are commonly used to remove biofouling, because they can oxidize and kill microorganisms. Therefore, our study aims to utilize NaOCl and ClO2 during the CF-RO process to minimize the algal growth within the system and minimize the fouling induced by EPS. Results from this study show that CF can remove more than 50% of protein and 14% of polysaccharides but is not effective in removing toxins. However, with disinfectants, toxic materials were completely oxidized. Improved removal of EPS with CF improved overall performance. The flux reduction in RO process without disinfection was over 60%, however, the flux decline was about 44% and 10% with NaOCl and ClO2, respectively. Both disinfectants were found to be effective, however use of ClO2 is recommended because it is less damaging the membrane, yet more effective in enhancing the performance.

Advances in the Role of Sodium Hypochlorite Irrigant in Chemical Preparation of Root Canal Treatment.

Irrigation of root canal system is of great significance to the success of endodontic treatment, where sodium hypochlorite (NaOCl) is the most widely used irrigant in chemical preparation. NaOCl functions by eliminating bacterial biofilms and dissolving organic tissue, which may vary according to several factors such as the microbiology of root canal infection and the concentration of the irrigant. It has been proposed that the effectiveness of NaOCl could be enhanced via several methods, including heating the irrigant, applying in conjunction with certain reagents, or activating by agitation techniques. Despite its antibacterial and tissue-dissolving capacities, NaOCl should be used with caution to avoid detrimental effect due to its cytotoxicity and negative effect on dentin properties. In this narrative review, we discussed the factors that affect the properties of NaOCl, the methods to improve its efficacy, and the side effects that might occur in clinical practice.

The Potential of Phenothiazines against Endodontic Pathogens: A Focus on Enterococcus-Candida Dual-Species Biofilm.

Persistent apical periodontitis occurs when the endodontic treatment fails to eradicate the intraradicular infection, and is mainly caused by Gram-positive bacteria and yeasts, such as Enterococcus faecalis and Candida albicans, respectively. Phenothiazines have been described as potential antimicrobials against bacteria and fungi. This study aimed to investigate the antimicrobial potential of promethazine (PMZ) and chlorpromazine (CPZ) against E. faecalis and C. albicans dual-species biofilms. The susceptibility of planktonic cells to phenothiazines, chlorhexidine (CHX) and sodium hypochlorite (NaOCl) was initially analyzed by broth microdilution. Interaction between phenothiazines and CHX was examined by chequerboard assay. The effect of NaOCl, PMZ, CPZ, CHX, PMZ + CHX, and CPZ + CHX on biofilms was investigated by susceptibility assays, biochemical and morphological analyses. Results were evaluated through one-way ANOVA and Tukey's multiple comparison post-test. PMZ, alone or in combination with irrigants, was the most efficient phenothiazine, capable of reducing cell counts, biomass, biovolume, carbohydrate and protein contents of dual-species biofilms. Neither PMZ nor CPZ increased the antimicrobial activity of CHX. Further investigations of the properties of phenothiazines should be performed to encourage their use in endodontic clinical practice.

Effect of NaOCl and EDTA irrigating solutions on the cyclic fatigue resistance of EdgeTaper Platinum instruments

BackgroundTo compare the solution on the cyclic fatigue resistance of EdgeTaper Platinum (ETP) instruments with that of ProTaper Gold (PTG) in the presence of ethylenediaminetetraacetic acid (EDTA) or sodium hypochlorite (NaOCl) irrigating solutions.MethodsSixty PTG and 60 ETP instruments with the same size (#25) and taper (8%) were tested under 17% EDTA, 5.25% NaOCl, or distilled water (n = 20 each). Cyclic fatigue was tested using artificial canals that were milled in stainless steel blocks using a laser micromachining technique. The canals had a curvature angle of 60 and a curvature radius of 5 mm. The center of maximum curvature was set at 5 mm from the instrument tip. The block of artificial canals was stabilized inside a container that was filled with one of the tested solutions. The temperature was fixed at 37 °C with a tolerance limit of 1 °C. The number of cycles to fracture (NCF) was calculated and the fractured surfaces were examined using a scanning electron microscope. All statistical analyses were performed using SPSS software Version 20 (IBM-SPSS Inc., Chicago, IL) at a confidence level of 95%.ResultsETP showed higher NCF than PTG in any of the tested solutions (P < 0.05). Within each group, NaOCl drastically decreased the NCF compared to water and EDTA (P < 0.05) and changing the solution from distilled water to EDTA did not affect the fatigue resistance (P > 0.05).ConclusionsETP showed improved cyclic fatigue performance compared to PTG in all tested irrigating solutions. EDTA can be used in combination with NiTi instruments during canal instrumentation without compromising the cyclic fatigue resistance of PTG and ETP instruments. However, NaOCl drastically decreased the NCF.

Effect of Lowering the pH of Sodium Hypochlorite on Control of Pseudomonas aeruginosa in Maintenance of Pharmaceutical Water System

Drinking water or potable water is a common source for generation of purified water or demineralized water which is used for processing of medicinal products such as tablets, capsules, syrups, and nasal sprays. Before allowing for purification, it is manufacturer’s responsibility to ensure the microbial load control in the source water to get good quality product water and to avoid biofilm formation in waterlines. The current research involves the study of an effectiveness of sodium hypochlorite (NaOCl) at various concentrations of water pH on microbial control by following pour plate technique. The aim of this study was to examine the effect of lowering the pH on the recovery of Pseudomonas aeruginosa. Three groups were tested by challenging known population of P. aeruginosa by varying the pH of 5.0, 7.0 and 9.0. No significant difference was observed at pH 5.0 and 7.0 and the recovery increased when the pH increased at 9.0. Effective microbial control was obtained at neutral pH. The increase of pH resulted decrease of effectiveness of NaOCl.

Effect of NaOCl, growth media, and plant growth regulators on in vitro propagation of disease-free KM140 cassava cultivar (Manihot esculenta Crantz)

Cassava mosaic disease (CMD) is one of the most dangerous diseases that has caused heavy losses in yield and starch content on cassava. In vitro propagation using disease-free cassava stakes was an optimal method to produce healthy seedlings. In this study, sodium hypochlorite (NaOCl), growth media (MS, ½ MS and Knudson C) and growth regulators (BA: Benzyl adenine, NAA: Naphthalene acetic acid, GA: Gibberellin) were used to determine an appropriate time for sample sterilization and the suitable concentration for shoot multiplication and root induction of KM140 cassava cultivar. The results showed that sample sterilization at 8% NaOCl concentration in 5 min gave the highest survival rate (71.7%) at 14 d of culture. Cassava explants cultured on MS medium supplemented with 1 mg/L BA gained the highest number of shoots (2.3 shoots), shoot height (10.3 mm) and the number of leaves (4.2 leaves/shoot) at 50 d of culture. The MS medium supplemented with 0.07 mg/L NAA and 0.03 mg/L GA was applicable for the rooting stage of KM140 cassava cultivar (19.8 roots/plantlet at 60 d of culture). The results of the study were fundamental to in vitro propagation process of disease-free KM140 cassava multiplication.

The influence of sodium hypochlorite concentration on the fibrin structure of human blood clots and transforming growth factor-beta 1 release: an ex vivo study.

This study investigated the effects of various concentrations of sodium hypochlorite (NaOCl) on human whole-blood clotting kinetics, the structure of the blood clots formed, and transforming growth factor (TGF)-β1 release. Human whole blood was collected from 5 healthy volunteers and divided into 4 groups: CG (control, 0.5 mL of blood), BN0.5 (0.5 mL of blood with 0.5 mL of 0.5% NaOCl), BN3 (0.5 mL of blood with 0.5 mL of 3% NaOCl), and BN5.25 (0.5 mL of blood with 0.5 mL of 5.25% NaOCl). The effects of NaOCl on clotting kinetics, structure of fibrin and cells, and release of TGF-β1 were assessed using thromboelastography (TEG), scanning electron microscopy (SEM), and enzyme-linked immunosobent assay, respectively. Statistical analysis was conducted using the Kruskal Wallis and Mann-Whitney U tests, followed by the post hoc Dunn test. A p value < 0.05 indicated statistical significance. The blood samples in BN0.5 and BN3 did not clot, whereas the TEG of BN5.25 showed altered clot formation. Samples from the CG and BN3 groups could only be processed with SEM, which showed that the latter lacked fibrin formation and branching of fibers, as well as clumping of red blood cells with surface roughening and distortion. TGF-β1 release was significantly highest in BN3 when all groups were compared to CG (p < 0.05). Each concentration of NaOCl affected the release of TGF-β1 from blood clots and altered the clotting mechanism of blood by affecting clotting kinetics and cell structure.

Mineral trioxide aggregate immersed in sodium hypochlorite reduce the osteoblastic differentiation of human periodontal ligament stem cells

White mineral trioxide aggregate (WMTA) is a root canal treatment material, which is known to exhibit a dark brown color when in contact with sodium hypochlorite solution (NaOCl). This study aimed to investigate the effects of NaOCl on the surface properties of WMTA discs and WMTA-induced osteoblastic differentiation of periodontal ligament stem cells (PDLSCs). Mixed WMTA (ProRoot MTA) was filled into the molds to form WMTA discs. These discs were immersed in distilled water (D-WMTA) or 5% NaOCl (Na-WMTA). Their surface structures and Ca2+ release level was investigated. Moreover, they were cultured with a clonal human PDLSC line (line 1–17 cells). The main crystal structures of Na-WMTA were identical to the structures of D-WMTA. Globular aggregates with polygonal and needle-like crystals were found on D-WMTA and Na-WMTA, which included Ca, Si, Al, C and O. However, many amorphous structures were also identified on Na-WMTA. These structures consisted of Na and Cl, but did not include Ca. NaOCl immersion also reduced Ca2+ release level from whole WMTA discs. Line 1–17 cells cultured with D-WMTA formed many mineralized nodules and exhibited high expression levels of osteoblast-related genes. However, cells incubated with Na-WMTA generated a small number of nodules and showed low expression levels of osteoblast-related genes. These results indicated that NaOCl reduced Ca2+ release from WMTA by generating amorphous structures and changing its elemental distribution. NaOCl may also partially abolish the ability of WMTA to stimulate osteoblastic differentiation of PDLSCs.

Experimental Solution of Chitosan and Nanochitosan on Wettability in Root Dentine: In Vitro Model Prior Regenerative Endodontics.

Aims To compare the effect of CS and CSnp on the wettability in root dentine with other irrigation protocols with an experimental in vitro model prior regenerative endodontics. Methods and Material. An in vitro experimental study that included eighty hemisected human root distributed into 8 groups: G1- distilled water; G2- 1% NaOCl/17% EDTA; G3- hypochlorous acid 0.025% HOCl, G4- 1% NaOCl/0.025% HOCl/17% EDTA, G5- 0.2 g/100 mL CS, G6- 1% NaOCl/0.2 g/100 mL CS, G7- CSnp, and G8- 1% NaOCl/CSnp. The wettability analysis calculated the contact angle (θ) between a drop of a blood-like and root dentinal surface; topographic characterization with scanning electron microscopy (SEM) quantified the diameter and number of tubules per area; spectroscopy infrared analyses (IR-S) identified chemical changes in the inorganic (phosphate/carbonate) and organic phase (amide/methyl). Statistical analysis: a linear mixed model, Kruskal–Wallis, and Holm–Bonferroni correction (P < 0.05) were used. Results Significantly higher wettability for G2 (27.1 (P = 0.0001)) was found. A mean value of 67°±°for experimental groups (P = 0.07) was found, and we did not identify differences between them. The SEM identified greater tubular opening and erosion for G4 and greater dentinal permeability per area for NaOCl/CS. IR-S identified dentinal organic integrity with NaOCl-CS/CSnp compared to organic reduction promoted for NaOCl/EDTA. Conclusions This in vitro dentin determined an indirect association between the wettability and organic contents. The oxidative effect of NaOCl could be neutralized by CS-CSnp, and consequently, the wettability of the substrate decreases.

Effect of intracanal and extracanal heating on pulp dissolution property of continuous chelation irrigant.

Context:Extracanal and intracanal heating of sodium hypochlorite (NaOCl) improve its pulp dissolution, but limited literature is available on its effect as a combined single irrigant with etidronate.Aim:The aim of this study is to compare the effect of temperature on the effectiveness of NaOCl and continuous chelation protocol on the time required for the dissolution of vital and necrotic pulp.Materials and Methods:Dissolution time of 120 standardized bovine (buffalo) pulp fragments, divided into 12 subgroups based on tissue type (vital/necrotic), irrigant (NaOCl/continuous chelation), and temperature (extracanal, intracanal, and nonheated irrigant), was noted. Conical glass tips mimicking the root canal were considered specimen containers. About 0.2 ml of irrigant corresponding to the irrigation protocol was taken in them and then pulp samples were added to it. Samples were observed using loupes under 2.5 X magnification. Dissolution time was recorded using a stopwatch. The study was approved by the Institutional Ethical Committee (SDC/2019/591).Statistical Analysis Used:Two-way analysis of variance; statistical product and service solutions version 25. The level of significance was set at P < 0.05.Results:Time for pulp dissolution by continuous chelation mixture was significantly more as compared to NaOCl alone in all subgroups. Pulp tissue dissolution for both vital and necrotic pulp was improved by the increase in temperature of both irrigants and dissolution time was more for necrotic than vital tissue. Pulp tissue dissolution was significantly better by intracanal heating as compared to extracanal heating.Conclusion:Although intracanal heating of continuous chelation mixture improves its pulp dissolution capacity significantly as compared to extracanal heating and nonheating protocol but pulpal dissolution capacity of nonheated 5% NaOCl still remains significantly better as compared to intracanal and extracanal heated continuous chelation mixture.

Deproteinizing agent, a fore step to better bonding: A literature review

Deproteinization can be defined as a process of removing the protein from a substance, usually as a stage in chemical purification. It is a necessary step in many procedures for the chemical analysis of body fluids. In dentistry, deproteinization can be used for elimination of the organic substances from the enamel surface before etching, as it increases the orthodontic bond strength by creating predominantly Type 1 and 2 etch patterns. Various authors have experimented the effect of enamel deproteinization with 5.25% sodium hypochlorite (NaOCl) prior to phosphoric acid etching and its effect on the etching pattern and shear bond strength of different adhesive systems. This article has reviewed and summarized the different studies regarding the effectiveness of NaOCl as a deproteinizing agent including its alternatives.

Biomechanical Effect of Irrigants in Noninstrumented Dentin: Systematic Review and Meta-Analysis

One aspect of special concern in endodontics is the effect of irrigating solutions on the biomechanical properties of dentine. A systematic review of in vitro studies was conducted to analyze and systematize the effect of endodontic irrigating solutions on biomechanical properties in noninstrumented dentine, according to published in vitro studies. A literature review was conducted on different databases including papers from 2009 to 2019. Two researchers identified in vitro studies on permanent teeth root dentine that reported control group, featured nonmechanical preparation, and sample size ≥ 10. An instrument was designed for bias assessment in three categories (High-Uncertain-Low), applying 17 criteria. Using the PRISMA tool, an electronic search found 9,026 titles. From these, 28 were subjected to full-text analysis and 9 were chosen for qualitative analysis. It was identified that chelates decrease microhardness and stiffness. It was also inferred that the proteolytic effect of NaOCl reduces the elasticity modulus and flexural strength. The heterogeneity analysis, with a value I2:92% for microhardness and I2:81% for roughness, revealed high heterogeneity among the included studies. The random effect model identified with 95% confidence that NaOCl and EDTA significantly decrease microhardness: -3.00[-4.22, -1.78]; EDTA 17% at 15 min being on average the lowest value: -6.66[-8.32, -5.00]. For roughness, all the proposed solutions increased significantly: 2.37[1.67, 3.08]; the highest, 3.94[2.84, 5.04], was recorded by NaOCl2.5%-15 min. In contrast, CLX registered a high roughness value: 3.33[1.88, 4.77]. Dentinal microhardness reduction associated to chelates is a concentration and time- dependent variable. Collagen degradation by NaOCl is a time and concentration-dependent variable.

Effect of NaOCl and EDTA as Post Space Cleansing Solutions on the Bond Strength of Resin Cements to Root Canal Dentin (An in vitro Study)

Aims: To evaluate the regional bond strength of four resin-based luting cements to post space dentin after irrigating with different irrigant solutions regimens. Materials and Methods: Eighty extracted human lower premolars were decoronated, instrumented, and obturated. Post space was prepared in each root, then randomly divided into four groups (n=20) according to the final irrigation regimen for the post space, Gp.1: distilled water (DW) control; Gp.2: 5.25% NaOCl+DW; Gp.3: 17%EDTA+DW; Gp.4: 5.25%NaOCl+17% EDTA+DW. Each group was further subdivided into four subgroups (n=5) according to the luting cements, Gp.(1,2,3,4)A (Vivaglass®Liner); Gp.(1,2,3,4)B (PermaCem®-Dual); Gp.(1,2,3,4)C (Variolink II); Gp.(1,2,3,4) D (LuxaCore®Z-Dual), then each post-space was sectioned horizontally into three slices. A push-out test was performed to measure regional bond strengths and the fracture modes was evaluated using a stereomicroscope. Results: The use of 5.25% NaOCl+17% EDTA+DW result in higher bond strength than other treatments. While the control group gives the lowest. (LuxaCore®Z-Dual) showed the highest bond strength than other resin cements. (Vivaglass®Liner) gives the lowest bond strength. The regional bond strengths decreased significantly toward the apical third. The failure mode recorded was mostly adhesive in nature except for groups (3D,4D) showed some mixed failure at the coronal third. Conclusions: NaOCl+ EDTA flush had a profound effect on resin bond strength to radicular dentin. (LuxaCore®Z-Dual) composite core buildup material exhibited the higher regional bond strength to radicular dentin. The regional bond strength decreased from coronal to apical direction.

The effect of NaOCl and heat treatment on static and dynamic mechanical properties and chemical changes of dentine

ObjectivesTo determine the effect of heat on flexural strength (FS), maximum strain (MS), storage modulus (SM), tan delta (TD) and chemical changes through micro-Raman spectroscopy of dentine exposed to 2.5% NaOCl or saline. Methodology: Dentine bars were randomly allocated to 8 test groups. Half (groups 2,4,6,8) were treated with NaOCl for 20 min; the rest (groups 1,3,5,7) remained in saline. FS/MS were measured in groups 1–4 (n = 15) (3/4 were also heated to 200 °C & re-hydrated in saline). Micro-Raman spectroscopy was performed on bars from groups 1–4. SM/TD were measured in 5–8: in 5/6 (n = 10), repeated after heating (200 °C), then following re-hydration; in 7/8 (n = 3) after heating to 25–185 °C. ResultsIncrease in MS on heat and FS/MS on heat + NaOCl was not significant (P > 0.05). SM increased (P = 0.06) after heat treatment but reduced to initial state after rehydration (P = 0.03). TD did not change (P = 0.4) after heat (200 °C) treatment but rehydration increased it compared with pre-treatment state (P = 0.001). For dentine bars pre-treated with NaOCl, SM did not change (P = 0.6) after heat (200 °C) treatment or rehydration but TD significantly increased (P = 0.02) upon re-hydration compared with pre- (P=0.007), or post- (P = 0.03) heat-treatment states. SM and TD varied between 25–185 °C with no consistent trend amongst the NaOCl pre-treated bars. Micro-Raman only detected chemical changes following NaOCl treatment in the mineral phase. ConclusionsExposure of dentine bars to heat and NaOCl produced only moderate changes to quasi-static but marked changes to viscoelastic properties, which may be explained by chemical alterations.

Effects of sodium hypochlorite concentration on the methanogenic activity in an anaerobic fluidized membrane bioreactor

The effect of membrane cleaning chemical, NaOCl on specific acetoclastic methanogenic activity (SAMA) of biomass in the anaerobic fluidized membrane bioreactors (AFMBRs) was assessed. Granular activated carbon (GAC) was used as a fluidizing media in the AFMBR to provide membrane scouring effect and surface for biofilm attachment. Effect of NaOCl on methane production was negligible for GAC with biofilm (bGAC) samples up to 150 mg NaOCl/g VSS, but was significant for the bulk liquid samples with noticeable lag period over 300 h even at the dosage of 50 mg NaOCl/g VSS. The toxicity of NaOCl on methane production was reduced in samples with virgin GAC (vGAC) by allowing 14 days of biomass buildup period prior to NaOCl addition, although the vGAC alone did not alleviate the toxicity. The results revealed that NaOCl concentrations beyond 100 mg/L within the reactor inhibited methanogenic activity and the effects were more pronounced on suspended biomass than the immobilized biomass on GAC.

Evaluation of the actual chlorine concentration and the required time for pulp dissolution using different sodium hypochlorite irrigating solutions.

Introduction:The goal of root canal treatment is to shape and clean the endodontic space, reducing the bacterial load and removing the pulp tissue. Obviously, the action of the endodontic instruments is limited to the main canals, regardless of the complexity of the endodontic space. Consequently, finding the best possible cleaning technique, which can be obtained chemically using irrigation solutions, is a fundamental aid in endodontic therapy. One of the most commonly used root canal irrigants is sodium hypochlorite (NaOCl), available in various commercial formulations. The effectiveness of NaOCl is undeniable. However, the action of dissolution of the pulp tissue is merely dependent on the concentration and the characteristics of the irrigant itself.Aim:The aim of this study is to evaluate the effective concentration of different commercial formulas of NaOCl, by evaluating the percentage of total chlorine in each product. The dissolution capacity of the pulp tissue of each of the tested products was then analyzed by measuring the required time.Materials and Methods:Three commercial types of NaOCl were selected for this study: 5% NaOCl (ACE, Procter and Gamble), 5% NaOCl (N5, Simit Dental), and 6% NaOCl (CanalPro, Coltene). For each product, 10 packages were used, from which samples of the product were taken and 30 ml × 5 ml tubes were filled. All samples were divided into three groups and were analyzed using the DIN EN ISO 7393-2 method and the percentage of total chlorine (expressed as a percentage) was calculated. Forty samples of vital pulp were obtained from teeth freshly extracted for periodontal reasons and stored in physiological solution. In order to unify the size and weight of the samples (0.0001 mg), a microtome and a precision balance (Pro Explorer Ohaus) were used. Each sample, carefully examined by stereomicroscope (×40), was placed in artificial plastic containers and submerged in 0.1 ml of irrigating solution at room temperature (26°C). A fourth control group used saline solution as irrigant. Simultaneously with the insertion of the irrigating solution, a digital stopwatch was activated and the time necessary for the complete dissolution of the pulp sample was measured. The data obtained was subjected to statistical analysis.Results:The average percentages of chlorine detected for each group were: 4.26% (ACE), 5.16% (N5), and 5.97% (CanalPro). The Kruskal–Wallis test showed statistically significant differences between the different commercial formulations of hypochlorite (P < 0.05). CanalPro showed the lowest values, whereas ACE showed the highest values of dissolution time of the pulp.Discussion:The analysis of the total chlorine percentage found that the actual concentration of the NaOCl in the samples is close to the values declared by the manufacturers both in the case of N5 and CanalPro. On the contrary, the concentration detected in the samples of common bench bleach (ACE) is significantly lower, which has average values <5%. This explains the longer time taken for the complete dissolution of the pulp tissue. The average dissolution time of the pulp samples was in fact inversely proportional to the concentration detected in the tested irrigants and hence that a lower time corresponds to a higher concentration.

Effect of NaOCl and EDTA Solutions on Topography of ESX, TruShape and ProTaper Gold NiTi Rotary Instruments - An Atomic Force Microscopic Study.

Aim:The study was aimed to evaluate the effect of 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) Solutions on Surface Topography of ESX, TruShape, and ProTaper Gold nickel-titanium (NiTi) Rotary Instruments using Atomic Force Microscope (AFM).Materials and Methodology:A total of 27 each of three commercially available brands of endodontic NiTi instruments were analyzed, which were divided into three groups as follows: Group I: ESX (Brasseler, USA) Group II: Tru shape (Dentsply Tulsa, USA) Group III: Pro Taper Gold (Dentsply Tulsa, USA). These files were further divided into three subgroups containing nine files each, no immersion, immersion in 5.25% NaOCl for 5 min, and immersion in 17% EDTA for 5 min. Surface areas along 3 mm sections at the tip of the files (perfect squares of 10 μm × 10 μm) were analyzed using AFM operating in contact mode under ambient conditions.Statistical Analysis:Data were analyzed using two-way ANOVA and pairwise comparison of three main groups with respect to Ra and RMS by Tukey's multiple posthoc procedures.Results:Three-dimensional AFM images of the surface of all the rotary NiTi instruments, including new and those immersed in 5.25% NaOCl and 17% EDTA solutions, revealed topographic irregularities at the nanometric scale. Ra and RMS values of instruments treated with 5.25% NaOCl and 17% EDTA solutions were statistically higher than that of the new ones (P < 0.05).Conclusion:Using AFM for analysis indicated that short-term contact between 5.25% NaOCl and 17% EDTA solutions and NiTi instruments caused alterations in the topography of instruments.

Membrane Bioreactors Used for Treatment of Food Industry Effluents

Effluents from the food industry determine pollution problems due to high COD and BOD concentrations. Compared to other industrial divisions, food industry requires large amounts of water. In this study, MBR was based on submerged hollow fibers membranes functioning by low vacuum. Two phases of bioreactor treatment were carried out with different HRTs (2-8) and (2-24) hours. Sixteen water samples collected from the influent and the effluent of the bioreactor during the two phases. NaOCl compound was added during the backwashing process for all tests, and the same compound was added with mixed liquid for the second test at period 24 hour of aeration. The samples were tested for twelve water quality tests: temperature, Dissolved Oxygen, pH, Turbidity, Total Suspended Solids, Mixed Liquor Suspended Solids, Chemical Oxygen Demand, Biochemical Oxygen Demand, Nitrate Nitrogen, Ammonium Nitrogen, Total Phosphate, and Ortho Phosphate. The results indicated that the bioreactor system can be used efficiently to treat industrial wastewater from the food industry. The efficiency of the technology was evaluated with sodium hypochlorite addition to removing the adherent bacteria on the surface area of hollow fibers. The results showed that the bioreactor under the conditions of the second phase was excellent in removing Turbidity, TSS, COD, and BOD5 with a removal efficiency 99.96%, 89.52%, 93.56%, and 99.36% respectively, when added 82 ml of NaOCl in the bioreactor tank, and was a good removing of TP, and Ortho-P with removal efficiency 60.76% and 48.95% respectively. Otherwise, a negative effect of NaOCl on both of NO3-N and NH4-N was obtained in term of removal where the minimum removal efficiency was observed when adding 82 ml of NaOCl under the conditions of the second phase.

A comparative Study to Evaluate the Effect of Sodium hypochlorite Temperature on Cyclic Fatigue Resistance of Three Types of Rotary Instrument

Background: The fracture of instruments within root canal during endodontictreatment is a common incidence, fracture of fatigue through flexure occursbecause of metal fatigue, NaOCl used for irrigation may have an effect oncorrosion that decrease fracture resistance. This study aimed to assess the effect ofNaOCl temperature on the cyclic fatigue of different type of Endodontic NiTiRotary Instruments and compare among them.Materials and method: three types of rotary instruments with tip size 0.25: ProTaPerF2 (Densply,Malifier) Revo-S SU ( 0.06 taper, MicroMega) and RaCe system(0.06 taper, FKG,Dentaire), Thirty file of each instrument type were used withincanal with 60° angle of curvature , undiluted NaOCl (5.25% ) were used. Ten filewithout immersion in NaOCl, ten were immersed at room temperature (21°C) for5 minute and ten with immersion in NaOCl at 60°C for the same time. Nine groupwere formed for all instruments (total number=90). The testing canal customizedwithin stainless steel block covered with glass face, the time to fracture recordedand the mean of cycles to fracture (MCF) detected for each instrument .Data wereanalyzed statistically by ANOVA, LSD and Independent T-test at 5% significantlevel.Result: there was a highly significant difference in mean of cycles to fracture for eachrotary instrument when temperature of NaOCl increased that the Number of cyclesto fracture decreased as the temperature increased. RaCe revealed the best fractureresistance followed by ProTaper then Revo-s that showed the less resistance.Conclusion: the rotary instruments more prone to fracture when temperature ofNaOCl increased, as well as the rotary instruments differ from each otheraccording to manufacturing process, taper, cross section and other factors.