Concentrations Of Sodium Hypochlorite Research Articles

Effect of UV Light and Sodium Hypochlorite on Formation and Destruction of Pseudomonas fluorescens Biofilm In Vitro

Pseudomonas fluorescens is one of the first colonizers of bacterial biofilm in water systems and a member of opportunistic premise plumbing pathogens (OPPPs). The aim of this study was to examine the effect of UV light and sodium hypochlorite on the formation and destruction of mature P. fluorescens biofilm on ceramic tiles. Planktonic bacteria or bacteria in mature biofilm were exposed to UV light (254 nm) for 5, 20 s. and to 0.4 mg/L sodium hypochlorite for 1 min. Mature biofilm was also exposed to increased concentration of sodium hypochlorite of 2 mg/L for 0.5, 1 and 2 h and combined with UV. Prolonged action of sodium hypochlorite and an increase in its concentration in combination with UV gave the best results in the inhibition of biofilm formation after the pre-treatment and destruction of mature biofilm. The effect of hyperchlorination in combination with UV radiation shows better results after a long exposure time, although even after 120 min there was no completely destroyed biofilm. Furthermore, the mechanism of the effect of combined methods should be explored as well as the importance of mechanical cleaning that is crucial in combating bacterial biofilm in swimming pools.

Assessing decontamination practices at a medical microbiology research laboratory

To our knowledge, this is the first study to conduct an objective assessment of the routine decontamination practices at a medical microbiology research laboratory (MRL) a year after a biosafety training was provided to all laboratory staff. Between March 28th and June 28th, 2021, unobtrusive observations were carried out to identify-three high-touch surfaces at the MRL during different working hours. Swabbing was used to evaluate the effectiveness of the disinfectant used in the laboratory. All three high-touch surfaces were sampled before and after decontamination with 200 ppm of 5 % sodium hypochlorite (household bleach) to quantify the microbial load and identify the types of organisms residing on the laboratory surfaces. A higher concentration (500 ppm) of 5 % sodium hypochlorite was employed after refresher training was provided to housekeeping staff, and resampling of the three surfaces was carried out during a 4-week follow-up period using the same procedure. The three high-touch surfaces identified were the two sides of the workbench (22 %–24 %) and the front surface of one incubator (14 %). Anthracoid bacilli and Staphylococcus aureus were the most commonly found organisms on laboratory surfaces pre-intervention (100 % and 89 %, respectively) and post-intervention (56 % and 44 %, respectively). Other microorganisms detected included Salmonella spp. (27.7 %), Proteus spp. (5.6 %), Escherichia coli (5.6 %), and Klebsiella spp. (33.3 %). Employing a higher concentration (500 ppm) of sodium hypochlorite significantly (p ≤ 0.000) reduced the total aerobic colony count from an average of 15–250 cfu/cm2 to 10–60 cfu/cm2. This study demonstrated suboptimal decontamination practices at the MRL and the need to apply a higher concentration (500 ppm) of sodium hypochlorite to reduce the overall microbial load. It also demonstrated the importance of quantitative assessment to monitor decontamination practices and ensure staff compliance. More studies are needed to identify bacterial communities within the laboratory, which will help provide guidance regarding the types, proper concentrations, and appropriateness of the in -use disinfectants. Furthermore, large-scale studies on the acceptable level of residual contamination following any decontamination process are urgently recommended.

Improvement the performance of TFC membranes by deposition a cationic/anionic polyelectrolyte onto their partially hypochlorite-degraded surfaces

Desalination using thin-film composite reverse osmosis (TFC-RO) polyamide (PA) membranes has been predominating for decades to reduce rising water demand. Organic fouling, which causes blocking of the membrane pores and hence a decline in permeability, is one of the main drawbacks of these membranes. Membrane surface modification has been a promising technique for enhancing flux permeability and antifouling characteristics. In this study, a novel coating process to modify the TFC membrane surface was developed. The coating is based on the deposition of supramolecular biodegradable cationic (chitosan, CS), anionic (sodium alginate, SA), and/or chitosan-alginate polyelectrolyte complexes onto the membranes surface using a layer-by-layer technique. To favor the deposition of the first layer of CS on the surface, the membranes first underwent a chlorine treatment to obtain more negative charges on the PA active layer. Different parameters of chlorination time and concentration of sodium hypochlorite, and concentration and time of the supramolecular deposition onto the membrane surface were studied. The appropriate conditions for the modification process were found to be as follows; NaOCl concentration of 5000 ppm, chlorination time of one hour, and polymer ratio of 1:1 (1000 ppm each). The chemical composition was confirmed using XPS and ATR-FTIR, and surface features were observed using SEM, zeta potential, and contact angle. The modified membrane was observed to be more hydrophilic with a twice increment of the water flux, 48 L/m2.h compared to 24.2 L/m2.h of the pristine membrane, and an insignificant change of salt rejection when treating a 5000 mg/L NaCl solution. The results showed that the coated membrane exhibited superior performance compared to the pristine membrane. In terms of antifouling properties, the coated membrane exhibited superior performance compared to the pristine membrane. Because the process is simple and all polymers are biodegradable, the proposed surface treatment could be a promising technique for membranes modification.

MODIFICATION OF LINDUR STARCH (Bruguiera Gymnorrhiza L.) BY OXIDATION USING SODIUM HYPOCLORITE AND FERRO SULPHATE CATALYST

Lindur fruit (Bruguiera gymnorrhiza L.) is widely available in Indonesia and has a high carbohydrate content, so it has the potential to be developed as a new source of energy and starch. So far, the use of lindur fruit is still limited to substitute rice and snacks. Therefore, it is necessary to make efforts to increase the utilization of lindur fruit by processing it into lindur starch and its derivatives (modified starch). The properties of lindur starch need to be improved in order to have wider uses in the food and non-food industries. The purpose of this study was to modify lindur starch by oxidation using NaOCl with ferrous sulfate as a catalyst. In this study, the effect of sodium hypochlorite concentration (2%, 4%, 6%, and 8%) and ferrous sulfate concentration (0%, 0.1%, 0.2%, and 0.3%) on the physicochemical characteristics of starch was studied. the resulting oxidized leachate and determined the optimal conditions. The results showed that all the variables studied affected the oxidation reaction of lindur starch. Oxidation at 4% NaOCl concentration and 0.2% ferrous sulfate concentration was able to produce the best values for carboxyl content, solubility, and swelling.

Effects of concentration of sodium hypochlorite as an endodontic irrigant on the mechanical and structural properties of root dentine: A laboratory study.

AimThe use of high‐concentration sodium hypochlorite (NaOCl) as an endodontic irrigant remains controversial because of its potential impact on the fracture strength of endodontically treated teeth. This study evaluated the effects of using different NaOCl concentrations, with 2‐min‐ethylenediaminetetraacetic acid (EDTA) as the final active irrigant, on the biomechanical and structural properties of root dentine.MethodologyA new test method, which is more clinically relevant, was utilized to calculate the fracture strength of root dentine. Bovine incisors were used to obtain root dentine discs. The root canals were enlarged to mean diameter of 2.90 mm with a taper of 0.06. The resulting discs were divided into five groups (n = 20) and treated with different concentrations of NaOCl (5.25%, 2.5%, and 1.3%) for 30 min plus 17% EDTA for 2 min. The discs were then loaded to fracture by a steel rod with the same taper through the central hole. The fractured specimens were examined by scanning electron microscopy to evaluate changes in the dimensions of the remaining intertubular dentine and the tubular radius. Micro‐hardness was also measured with a Knoop diamond indenter along a radius to determine the depth of dentine eroded by the irrigation. Results were analysed by one‐way anova and the Tukey test. The level of significance was set at α = 0.05.ResultsThe damage by NaOCl increased with its concentration. 5.25% NaOCl greatly reduced the fracture strength of root dentine from 172.10 ± 30.13 MPa to 114.58 ± 26.74 MPa. The corresponding reduction in micro‐hardness at the root canal wall was 34.1%. The damages reached a depth of up to 400 μm (p < .05). Structural changes involved the degradation of the intratubular wall leading to enlarged dentinal tubules and the loss of intertubular dentine. Changes in the microstructural parameters showed positive linear relationships with the fracture strength.ConclusionsWith the adjunctive use of EDTA, NaOCl caused destruction to the intratubular surface near the root canal and, consequently, reduced the root dentine's mechanical strength. The higher the concentration of NaOCl, the greater the effect. Therefore, endodontists should avoid using overly high concentration of NaOCl for irrigation to prevent potential root fracture in endodontically treated teeth.

Assessment of Surface Disinfection Effectiveness of Decontamination System COUNTERFOG® SDR-F05A+ Against Bacteriophage ɸ29

The experience of COVID19 pandemic has demonstrated the real concern of biological agents dispersed in the air and surfaces environments. Therefore, the need of a fast and large-scale disinfection method has arisen for prevention of contagion. COUNTERFOG® is an innovative technology developed for large-scale decontamination of air and surfaces. The objective of this study is to assess experimentally the effectiveness of COUNTERFOG® in disinfecting viral-contaminated surfaces. We also aim to measure the necessary time to disinfect said surfaces. Stainless steel surfaces were contaminated with bacteriophage φ29 and disinfected using COUNTERFOG® SDR-F05A+, which uses a sodium hypochlorite solution at different concentrations and for different exposure times. A log reduction over 6 logs of virus titer is obtained in 1 min with 1.2% sodium hypochlorite when the application is direct; while at a radial distance of 5 cm from the point of application the disinfection reaches a reduction of 5.5 logs in 8 min. In the same way, a higher dilution of the sodium hypochlorite concentration (0.7% NaOCl) requires more exposure time (16 min) to obtain the same log reduction (> 6 logs). COUNTERFOG® creates, in a short time and at a distance of 2 m from the point of application, a thin layer of disinfectant that covers the surfaces. The selection of the concentration and exposure time is critical for the efficacy of disinfection. These tests demonstrate that a concentration between 0.7- 1.2% sodium hypochlorite is enough for a fast and efficient ɸ29 phage inactivation. The fact that ɸ29 phage is more resistant to disinfection than SARS-CoV-2 sustains this disinfection procedure.

Electroleaching kinetics of molybdenite concentrate of Sarcheshmeh copper complex in chloride media

The kinetics of molybdenum and copper extraction from Sarcheshmeh molybdenite concentrate (Kerman, Iran) was studied by electroleaching process in batch mode. The effects of several critical parameters including sodium chloride concentration, pH, temperature, time, operating voltage, and the sodium carbonate addition on the molybdenum and copper extraction from the concentrate were investigated. Results showed that the molybdenum extraction significantly increased by increasing sodium chloride concentration, temperature, time, operating voltage, and sodium carbonate addition during the process. While with increasing pH, the molybdenum extraction decreased. Maximum molybdenum extraction (89%) was obtained at the sodium hypochlorite concentration of 30 g/L, the pH of 9, the temperature of 50 °C, operating voltage of 5 V, and reaction time of 4 h. Copper extraction was determined 17.5% in 30 min, which decreased to 3.9% over 8 h. It was found that carbonate ions added to the electroleaching process had a significant effect on molybdenum extraction. Also, carbonate ions might prevent hypochlorite decomposition by stabilizing copper (III) ions. The catalytic compounds of copper precipitate simultaneously with the catalytic decomposition of the hypochlorite. Kinetic studies have shown that the dissolution of molybdenite concentrate is described by a shrinking core model controlled by a chemical reaction. The activation energy for the electroleaching process of molybdenite concentrate was determined to be 29.4 kJ/mol. It seems that electroleaching is an efficient, green, and selective process for treating molybdenite concentrates.

Physicochemical properties of potato starches oxidised by different concentrations of sodium hypochlorite, and their application in yogurt

Potato starch was modified by oxidation with different concentrations of active chlorine (0.5, 1.0, 2.0, 3.0, and 4.0%); and the physicochemical properties of the oxidised potato starch samples and the use of these starches in set yogurt were investigated as a function of their degree of oxidation. The carboxyl content, carbonyl content, and solubility of the oxidised starches increased with increasing sodium hypochlorite concentrations, while the swelling power decreased. Scanning electron microscopy showed that oxidation caused cracks or pores on the surfaces of the starch granules, and these morphological changes were enhanced by increased oxidant concentrations. Analysis with a Rapid Visco Analyser showed that high degrees of oxidation could improve the starch thermodynamic stability and resistance to retrogradation. Set yogurts made with oxidised potato starches had higher water-holding capacities, higher apparent viscosities, and better sensory qualities than those prepared with native starch.

Analysis of the Metabolic Response of Planktonic Cells and Biofilms of Klebsiella pneumoniae to Sublethal Disinfection with Sodium Hypochlorite Measured by NMR.

Klebsiella pneumoniae is a pathogenic agent able to form biofilms on water storage tanks and pipe walls. This opportunistic pathogen can generate a thick layer as one of its essential virulence factors, enabling the bacteria to survive disinfection processes and thus develop drug resistance. Understanding the metabolic differences between biofilm and planktonic cells of the K. pneumoniae response to NaClO is key to developing strategies to control its spread. In this study, we performed an NMR metabolic profile analysis to compare the response to a sublethal concentration of sodium hypochlorite of biofilm and planktonic cells of K. pneumoniae cultured inside silicone tubing. Metabolic profiles revealed changes in the metabolism of planktonic cells after a contact time of 10 min with 7 mg L−1 of sodium hypochlorite. A decrease in the production of metabolites such as lactate, acetate, ethanol, and succinate in this cell type was observed, thus indicating a disruption of glucose intake. In contrast, the biofilms displayed a high metabolic heterogeneity, and the treatment did not affect their metabolic signature.

Rapid germination and development of Acacia sieberiana DC in vitro

Acacia sieberiana is an ecological and economical important forest tree. The plant has poor germination due to dormancy; therefore, in vitro culture can provide a fast supply of plantlets and can be a basis for further biotechnology research. The effect of sodium hypochlorite, Murashige and Skoog (MS) medium, sucrose and cytokinin were investigated. The results indicated that all the treatments induced significant (P &lt; 0.05) effects on germination and seedling development depending on their concentrations. Germinates free of contamination were established successfully with all the concentrations of sodium hypochlorite, however, the germination was reduced as the concentration increased. A higher germination rate of 98.3% was attained with full MS strength and 3% sucrose concentration. The highest germination percentage obtained was 100% with 2 mg/L thidiazuron. The maximum shoot length (13.5 cm) and seedling dry weight (0.49 g) were recorded on full MS medium while the maximum root length (13.4 cm) was obtained on ½ MS strength. However, when full MS medium augmented with 5% sucrose enhanced shoot length and dry weight to (14.2 cm) and (0.5 g), respectively. While the highest root length (10.2 cm) was obtained by 3% provided in full MS medium. Application of cytokinins improved the number of node and dry weight of seedlings to 6.9 nodes with 4 mg/L thidiazuron and 0.54 g by 2 mg/L benzyladenine. The present study describes the establishment of in vitro seed germination and seedling growth system for A. sieberiana for the first time.

Phenotype and genetic determination of resistance to common disinfectants among biofilm-producing and non-producing Pseudomonas aeruginosa strains from clinical specimens in Iran

BackgroundPseudomonas aeruginosa is a common pathogen in Hospitalized patients, and its various resistance mechanisms contribute to patient morbidity and mortality. The main aims of the present study were to assess the susceptibility of biofilm-producing and non-producing P. aeruginosa isolates to the five commonly used Hospital disinfectants, to evaluate the synergistic effect of selected disinfectants and Ethylene-diamine-tetra acetic acid (EDTA), and the effect of exposure to sub-inhibitory concentrations of Sodium hypochlorite on antimicrobial susceptibility test.ResultsThe results showed that sodium hypochlorite 5% and Ethanol 70% were the most and least effective disinfectants against P. aeruginosa, respectively. The addition of EDTA significantly increased the effectiveness of the selected disinfectants. The changes in the antibiotic-resistance profiles after exposure to sub-inhibitory concentrations of disinfectants were observed for different classes of antibiotics (Carbapenems, Aminoglycosides, Cephalosporins, Fluoroquinolones). As well as near the all isolates harbored efflux pump genes and 117 (97.5%) of isolates produced biofilm.ConclusionIn the current study, the mixture of disinfectant and EDTA were the most suitable selection to disinfect Hospital surfaces and instruments. Also, it was clear that exposure to sub-inhibitory concentrations of Sodium hypochlorite results in resistance to some antibiotics in P. aeruginosa species. Strong and intermediate biofilm formers belonged to MDR/XDR strains. Future studies should include more complex microbial communities residing in the Hospitals, and more disinfectants use in Hospitals.

Surface Sterilization of Mango’s Mistletoe Leaves (Dendrophtoe pentandra (L.) Miq.) for Endophytic Fungi Isolation

Mango mistletoe (Dendrophthoe pentandra L. Miq) is known as a parasitic plant that has been scientifically proven to have the potential as an antihypertensive adjuvant herbal. The content of secondary metabolites in plants is produced by plants andby microorganisms that grow in plant tissues. One of them is endophytic fungi which can induce the host to produce secondary metabolites. The ability of endophytic fungi to synthesize secondary metabolites is an opportunity for the large-scale production of phytopharmaca raw materials in a short time without causing ecological damage. Before isolating endophytic fungi from the plant tissue, one needs to research surface sterilization to remove various kinds of microorganisms that are not desired. This study aims to determine the best method’s surface sterilization of the mango’s mistletoe leaves (Dendrophthoe pentandra (L.) Miq) to isolate endophytic fungi. This study used a two-factor completely randomized design. The concentration of Sodium Hypochlorite (NaOCl) was 5% and 10% as the first factor, and the immersion time of 1, 2, 3, 4, and 5 minutes was the second factor. There is a total of 10 treatments. In each treatment, there were three replications and one control. Observational data were analyzed descriptively. The results showed that application of NaOCl 10% for 3 minutes is the best and recommended method’s surface sterilization of the mango’s mistletoe leaves because the percentage of live explants is 100%, the percentage of contamination is 0%, and the percentage of explants with endophytic fungi is 100%.

Improving astaxanthin production of Haematococcus pluvialis on the outdoor large scale cultivation by optimizing the disinfection strategy of photobioreactor

Astaxanthin production is often plagued by biological contaminants during the outdoor culture of Haematococcus pluvialis. The contaminants may even lead to the failure of the whole cultivation. To reduce the contaminants during outdoor culture and ensure the stability of large-scale astaxanthin production, the disinfection strategies using sodium hypochlorite in outdoor closed horizontal tube photobioreactor (HTPBR) were studied. The effective concentration of sodium hypochlorite for disinfection was 80 mg·L−1 by comparing the tolerances of various kinds of biological contaminants to sodium hypochlorite. Moreover, a degradation model of sodium hypochlorite was established to quantify the concentration of residual sodium hypochlorite in HTPBR. The predicted value of this model was close to the measured value, the maximum deviation was 4.88 mg·L−1, and the average deviation was 1.97 mg·L−1. In order to avoid adverse effects on astaxanthin accumulation, the residual sodium hypochlorite or sodium thiosulfate after disinfection should be controlled below 0.1 mg·L−1and 10 mg·L−1, respectively. By comparing the multiple disinfection effects on outdoor HTPBRs, a low level of the total bacterial count was observed in HTPBR with double disinfection. By optimizing the disinfection strategy, the biological contaminants were reduced, and the volume content of astaxanthin was 2.37 times that of the unoptimized disinfection strategy. This study indicated that the astaxanthin yield can be improved by reducing the biological contaminants during the culture of H. pluvialis. The information will be a foundation for the disinfection strategy of other microalgae cultivation reactors.

Laser activated irrigation with SWEEPS modality reduces concentration of sodium hypochlorite in root canal irrigation

IntroductionShockwave enhanced emission photoacoustic streaming (SWEEPS) of Er: YAG laser has been proposed to improve the disinfecting efficacy of endodontic treatments. The purpose of this in vitro study was to compare the effects of different concentrations of sodium hypochlorite (NaOCl) combined with SWEEPS root canal irrigation on the removal of Enterococcus faecalis (E.faecalis) in infected bovine root canals. Materials and methodsForty-eight bovine root canals infected with E.faecalis were randomly divided into six groups. The root canals were irrigated by normal saline (NS) in combination with conventional needle irrigation (CI) , NS and different concentrations of NaOCl (0.5%, 1.0%, 2.0%, and 5.25%) in combination with SWEEPS. Then, the remaining live microbes from all specimens before and after root canal irrigation were collected and recovered via plate counting of the colony-forming unit (CFU). The CFU data were statistically analyzed by the Kruskal-Wallis H test. ResultsAfter root canal irrigation, the viable count in each group was significantly reduced (P < 0.05). The bacterial reduction in NS+CI and NS+SWEEPS groups was significantly lower than that in other groups (P < 0.05), and there was no significant difference among the other groups, or between these two groups (P > 0.05). ConclusionsThis study showed that SWEEPS used for root canal irrigation can enhance the effect of low-concentration NaOCl while ensuring the antimicrobial effect.

The Products of Probiotic Bacteria Effectively Treat Persistent Enterococcus faecalis Biofilms.

Objectives: Enterococcus faecalis is a Gram-positive commensal bacterium that possesses various survival and virulence factors, including the ability to compete with other microorganisms, invade dentinal tubules, and resist nutritional deprivation. E. faecalis is associated with persistent endodontic infections where biofilms formed by this bacterium in the root canal frequently resist dental therapies. Aseptic techniques, such as the inclusion of sodium hypochlorite, are the most commonly used methods to treat E. faecalis infections within the root canal system. In this work, we assess the effectiveness of probiotic strains to prevent the regrowth of E. faecalis biofilm cells treated by sodium hypochlorite irrigation. Methods: First, methods are presented that evaluate the effects of short-term exposure to sodium-hypochlorite on established E. faecalis. Next, we evaluate the effects of the secreted products of probiotic strains on biofilm cells and planktonic cells. Results: Sodium hypochlorite, the treatment conventionally used to decontaminate infected root canal systems, was extremely toxic to planktonic bacteria but did not fully eradicate biofilm cells. Furthermore, low concentrations of sodium hypochlorite induced eDNA dependent biofilms. Strikingly, conditioned medium from the probiotic bacteria Lactobacillus plantarum and Lactobacillus casei was sufficient to fully prevent the regrowth of treated biofilms while showing reduced potency towards planktonic cells. Conclusion: Sodium hypochlorite irrigations may contribute to the persistence of biofilm cells if used at concentrations lower than 3%. Probiotic strains and their products represent a new reservoir of biofilm therapies for E. faecalis infections formed in the root canal system.

Leaching of organic matters and formation of disinfection by-product as a result of presence of microplastics in natural freshwaters

Microplastics (MPs) are ubiquitous in the environment that may cause negative impacts on the aquatic organisms and human health. They exist in water and wastewater, which are from several sources, such as inappropriate disposal and littering. Therefore, it is important to evaluate the characteristics of MPs in different water types and oxidation processes and study dissolved organic carbon (DOC) leaching and chloroform formation. A commonly existing plastic matter, polyethylene (PE) was placed in different waters and gone through the Fenton-like reaction and the chlorination. The result showed that the PE leached nearly a similar amount of DOC (<1 mg L−1), which was regardless of the water types and under low-dosed irradiation/dark environment. The leached DOC caused the chloroform formation after the chlorination in the waters. During the Fenton-like reaction with the PE, a higher amount of leached DOC (∼3 mg L−1) was detected compared with that in the chlorination (∼0.8 mg L−1). The degree of DOC leaching from the PE caused by the oxidation processes was reflected by the degree of surface structural damage on the PE. However, the chlorination resulted in a higher chloroform formation from the PE (∼20 μg L−1) as the Fenton-like reaction degraded the chloroform. The higher the sodium hypochlorite concentration, the higher the chloroform concentration. When the chloroform existed in the water with the PE, adsorption of chloroform onto the PE was initially observed; however the rate of volatilization would be higher than the rate of adsorption eventually. This study offers useful information for the risk assessment of MPs in our fresh water and drinking water and possible mitigation strategies.

Influence of sodium hypochlorite concentration on cavitation effect and fluid dynamics induced by photon-induced photoacoustic streaming (PIPS): A visualization study.

The aim of the present study was to visualize and compare the cavitation effect and fluid dynamics induced by photon-induced photoacoustic streaming (PIPS) using sodium hypochlorite (NaOCl) with different concentrationsas irrigant. Forty artificial root canals were prepared using MTWO Niti file up to size #25/.06. The canals were randomly divided into four groups (n = 10/group). High-speed camera was used to visualize and compare the cavitation effect induced by PIPS in the artificial root canals containing saline or NaOCl. Fluid velocity and Reynolds number of saline, 1%-, 2.5%-and 5.25% NaOCl irrigants induced by PIPS in the apical region were calculated using TEMA 2D software while the fluid motions were recorded. Visualization profile revealed that NaOCl presented a stronger cavitation effect and fluid dynamics than saline during PIPS activation. In the apical region, 1% NaOCl group presented the highest average velocity of 3.868m/s, followed by 2.5% NaOCl group (3.685m/s), 5.25% NaOCl group (2.353m/s) and saline group (1.268m/s), corresponding to Reynolds number of 1653.173, 1572.196, 995.503 and 477.692. Statistically higher fluid velocity was calculated in 1% and 2.5% NaOCl groups compared to saline group, respectively (p < 0.05). The application of NaOCl and its concentration significantly influence the cavitation effect and fluid dynamics during PIPS activation. 1% and 2.5% NaOCl groups presented a more violent fluid motion in the apical region when activated by PIPS.

Effects of different concentrations of sodium hypochlorite on dentine adhesion and the recovery application of sodium erythorbate.

Root canal therapy is the most effective and common method for pulpitis and periapical periodontitis. During the root canal preparation, chemical irrigation plays a key role. However, sodium hypochlorite (NaOCl), the widely used irrigation fluid, may impact the bonding strength between dentin and restorative material meanwhile sterilization and dissolving. Therefore, it's important to explore the influence of NaOCl on the adhesion between dentin and restoration materials to ensure clinical efficacy. This study aims to explore the effect of NaOCl on dentine adhesion and evaluate the effect of dentine adhesion induced by sodium erythorbate (ERY), and to provide clinical guidance on dentin bonding after root canal therapy. Seventy freshly complete extracted human third molars aged 18-33 years old, without caries and restorations were selected. A diamond saw was used under running water to achieve dentine fragments which were divided into 10 groups with 14 fragments in each group: 2 control [deionized water (DW)±10% ERY] and 8 experimental groups (0.5%, 1%, 2.5%, and 5.25% NaOCl±10% ERY). The dentine specimens in the control group (treated with DW) and the experimental groups (treated with 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl) were immersed for 20 min using corresponding solutions which were renewed every 5 min. The other 5 groups were immersed in 10% ERY for 5 min after an initial washing with DW for 1 min. Then, we selected 4 dentine fragments from all 14 fragments in each group and the numbers and diameters of opening dentinal tubules were observed under scanning electron microscope (SEM). The other 10 dentine fragments from each group were used to make adhesive samples by using self-etch adhesive wand composite resin. All the above adhesive samples were sectioned perpendicular to the bonded interface into 20 slabs with a cross-sectional area of 1 mm×1 mm using a diamond saw under the cooling water, and then the morphology of 10 slabs in each group's bonding interface was observed from aspects of formation of resin tags, depth of tags in dentin, and formation of hybrid layer under SEM. The other 10 slabs of each group's microtensile bond strength and failure modes were also analyzed. Among the 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules gradually increased with the rise of concentration of NaOCl solution (all P<0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, 2.5% NaOCl, and 5.25% NaOCl groups, the number and diameter of patent dentinal tubules increased after using ERY, but without significant difference (all P>0.05). Among the DW, 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, the scores of formation of resin tags under SEM gradually increased with the increase of concentration of NaOCl solution, while the score in the 5.25% NaOCl group decreased significantly compared with the score of the 2.5% NaOCl group (P<0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (all P>0.05). The scores of length of the tags under SEM in the 5.25% NaOCl group was significantly higher than the scores of DW, 0.5% NaOCl, and 1% NaOCl groups (all P<0.05), and it was also higher than the score of the 2.5% NaOCl group, but without significant difference (P>0.05). There was no significant difference between using 10% ERY groups and without using 10% ERY groups (P>0.05). The scores of formation of hybrid layer under SEM in the 2.5% NaOCl and 5.25% NaOCl groups significantly decreased compared with the score of the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). Microtensile bond strength was greater in the 0.5% NaOCl, 1% NaOCl, and 2.5% NaOCl groups, but lower in the 5.25% NaOCl group than that in the DW group (all P<0.05). There were significant differences between the 2.5% NaOCl±10% ERY groups and between the 5.25% NaOCl±10% ERY groups (all P<0.05). The incidence of type "Adhesive" of failure modes in the 5.25% NaOCl group was significantly higher than that in other groups (all P<0.05), while the incidence of type "Adhesive" in the 5.25% NaOCl+10% ERY group was lower than that in the 5.25% NaOCl group (P<0.05). The bonding strength to dentine increases with the increase of NaOCl concentration when the concentration lower than 2.5%; whereas it is decreased at a higher concentration (such as 5.25%). 10% ERY has a definite recovery effect on attenuated bonding strength to 5.25% NaOCl-treated dentine.

Effect of Sodium Hypochlorite Concentration on Electronic Apex Locator Reliability.

This ex vivo study aimed to measure the performance of an electronic apex locator (EAL) in the presence of sodium hypochlorite irrigants with different concentrations. Two EALs (Root ZX Mini and Locapex 6) were used to locate the apical foramen in 10 extracted single-rooted teeth in the presence of 0.5%, 2.5% and 5% sodium hypochlorite. Visual working lengths were also determined using #10 K-file under a microscope before the electronic measurements were made. The performance of both EALs was compared for the electronic working lengths determined under the different concentrations of sodium hypochlorite. A multiple-way ANOVA and PLSD Fisher’s test with an α risk fixed at 5% were conducted. There were no statistical differences in the working lengths determined by both EALs between the three groups with different concentrations of sodium hypochlorite and their visual control measurements. When a ± 0.5 mm margin was applied, the Root ZX Mini and the Locapex 6 presented 88% and 83% accuracy, respectively. Sodium hypochlorite concentration in irrigants does not affect the accuracy and reliability of either the Root ZX Mini or the Locapex 6. Electronic apex locators are reliable with any concentration of sodium hypochlorite irrigants.

Leakage of Endotoxins through the Endotoxin Retentive Filter: An in vitro Study

Introduction: Ultrapurification of dialysis fluid has enabled highly efficient dialysis treatments. Online hemodiafiltration is one such treatment that uses a purified dialysis fluid as a supplemental fluid. In this method, an endotoxin retentive filter (ETRF) is used in the final step of dialysis fluid purification, with the aim of preventing leakage of endotoxins. Sodium hypochlorite and peracetic acid are used as disinfecting agents for the dialysis fluid pipes containing the ETRF; however, the effects of these agents on ETRF membrane pores have not been fully clarified. Methods: Water permeability (flux) and endotoxin permeability were assessed in 3 types of ETRFs made with different membrane materials: polyester polymer alloy (PEPA), polyether sulfone (PES), and polysulfone (PS). High-concentration sodium hypochlorite and 2 types of peracetic acid were used as disinfecting agents, and the changes in flux and the endotoxin sieving coefficient (SC) were measured. Results: After repeated use of high concentrations of sodium hypochlorite and peracetic acid, the PEPA and PES ETRFs did not permit passage of endotoxins, regardless of their flux. However, in the PS ETRF, the flux and endotoxin SC increased with the number of cleaning cycles. No differences were observed according to the concentration of peracetic acid disinfecting agents. Conclusion: PEPA and PES ETRFs completely prevent endotoxin leakage and can be disinfected at concentrations higher than the conventionally recommended concentration without affecting pore expansion. Even new PS ETRFs have low levels of endotoxin leakage, which increase after disinfection cycles using sodium hypochlorite and peracetic acid.