The shelf-life of sodium hypochlorite irrigating solutions

Irrigants and irrigation activation systems in Endodontics

Root canal infections are typically polymicrobial and involve strong bacterial interactions. The goal of endodontic treatment is to remove infected content from the root canal system to allow the healing of a pre-existing periapical lesion or to prevent infection of the periradicular tissues. Instrumentation alone is not capable of touching all of the root canal walls. Therefore, the irrigation process is an essential step in the endodontic treatment. However, due to the complex anatomy of the root canal system, this cleaning is very challenging. Although syringe and needle irrigation associated with the use of chemical substances is still the most used method, it does not guarantee optimal cleaning of the root canals. As a result, not only alternative irrigating substances but also numerous activation systems - which are technologies that aim to optimize the action of irrigating substances, both chemically and physically - have been developed. This work aimed to review the characteristics of both classic and current alternatives of irrigating substances and irrigation activation systems.

Surface Disinfection Practice in Public Hospitals in the Era of COVID-19: Assessment of Disinfectant Solution Preparation and Use in Addis Ababa, Ethiopia

Background

Surface disinfection of healthcare facilities with appropriate disinfectants is among the infection control strategies against the spread of coronavirus disease 2019 (COVID-19). As sodium hypochlorite solution (SHS) is a commonly used surface disinfectant, its preparation and proper use should be given a due attention. The current study aimed at assessing the practice of Addis Ababa public hospitals in the preparation and use of SHS.

Methods

A cross-sectional observational study was employed to assess the adequacy of disinfectant solution preparation and use. Checklists were used for data collection. Descriptive statistics were used for data analyses, and categorical variables were described by frequencies and percentages.

Results

Out of the twelve public hospitals included in the study; only three hospitals checked the potency of the working SHS. Majority of the hospitals (8 hospitals) stored the concentrated SHS products in cool, dry, and direct sunlight protected places. It was only in one hospital where appropriate personal protective equipment was used during the preparation and quality control activities. Surfaces were not cleaned in all hospitals before disinfection; and the rooms were ventilated only in 2 hospitals during the application of the disinfectant solution.

Conclusion

The study revealed that the preparations of SHS in the public hospitals did not comply with most of the requirements of good compounding practice. Moreover, standard practices were not maintained in majority hospitals during the use of SHS for surface disinfection. As a control strategy in the spread of COVID-19 and other infections, appropriate corrective actions shall be implemented in the studied hospitals to mitigate the limitations observed in the preparation and use of SHS.

Interactions between calcium hypochlorite and irrigants commonly used in endodontic practice: a chemical analysis

INTRODUCTION

This study aimed to identify possible products resulting from chemical interactions between calcium hypochlorite [Ca(OCl)₂] and other irrigants for endodontic use using electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOF-MS).

METHODS

The 5.25% Ca(OCl)₂ was associated with either 70% ethanol solution, distilled water, saline solution (0.9% sodium chloride), 5% sodium thiosulfate, 10% citric acid, 17% EDTA, or 2% chlorhexidine (CHX). The reaction ratio was 1:1 and the products obtained were analyzed by ESI-QTOF-MS.

RESULTS

The interactions between Ca(OCl)₂ and CHX generated an orange-brown precipitate, without identification of para-chloroaniline (PCA), and between Ca(OCl)₂ and sodium thiosulfate a milky-white precipitate. Furthermore, when the oxidizing agent was associated with EDTA and citric acid, chlorine gas was released. As for the other associations, 70% ethanol, distilled water, and saline solution, no precipitation or gas release occurred.

CONCLUSION

The orange-brown precipitate occurs due to the chlorination of guanidine nitrogens, and the milky-white precipitate is due to the partial neutralization of the oxidizing agent. The release of chlorine gas occurs due to the low pH of the mixture, which results in the rapid formation and decomposition of chlorine. In this context, an intermediate rinsed with distilled water, saline solution and ethanol between Ca(OCl)₂ and CHX, citric acid and EDTA seems to be appropriate to prevent the formation of by-products when these irrigants need to be used in the canal. Furthermore, if it is necessary to use sodium thiosulfate, a larger volume of the solution must be used than that used for the oxidizing solution.

Evidence-based Standard Operating Procedures FoR the Prevention and Management of Sodium Hypochlorite Accidents in Dentistry

This article aims to reduce harm and improve patient safety in dentistry by providing evidence-based guidance on the prevention, recognition, management, and reporting of sodium hypochlorite injuries occurring in the course of endodontic dental treatment. In contrast to previous publications all types of sodium hypochlorite harm and near-harm events in the dental setting are considered, to offer the reader an all-encompassing clinical guide for reference.

Application of Prussian Blue in Electrochemical and Optical Sensing of Free Chlorine

In this paper, an electrochemical free chlorine (FCL) sensor was formed by modifying a fluorine-doped tin oxide-coated glass slide (glass|FTO) with a layer of Prussian blue (glass|FTO|PB). The glass|FTO|PB sensor exhibited a wide linear detection range from 1.7 to 99.2 μmol L^-1 of FCL with a sensitivity of ~0.8 µA cm^-2 μmol^-1 L and showed high selectivity for FCL. However, ClO3-, ClO4- and NO3- ions have induced only a negligible amperometric response that is highly beneficial for a real-life sample analysis as these ions are commonly found in chlorine-treated water. Moreover, in this work, optical absorption measurement-based investigations of partially reduced PB were carried out as a means to characterize PB catalytic activity towards FCL and to investigate the possibility of applying PB for the optical detection of FCL.

Stability of Free Available Chlorine Levels in Dilute Sodium Hypochlorite Solutions over a 6-Week Period

Animal care and use programs commonly use chlorine and chlorine-based disinfectants to help prevent facility acquired infections in animals. The Department of Comparative Medicine (DCM) at Oregon Health and Science University (OHSU) follows the Centers for Disease Control and Prevention (CDC) disinfection guidelines for preparing and storing these disinfectants. DCM prepares bottles of dilute solutions of sodium hypochlorite (that is, commercial bleach) daily. In this study, we tested whether dilute bleach solutions, as prepared following the DCM protocol, remained stable under real-world practice conditions for up to 6 wk. We tested 4 groups of spray bottles filled with 0.5% bleach solutions in these experiments. Specifically, we sprayed 2 groups of bottles daily to mimic use while 2 other groups of bottles were not sprayed. We then measured free available chlorine (FAC) using 2 methods, spectrophotometry and colorimetric strips. All 4 test groups showed stable maintenance of FAC concentration for the length of the experiment. Mean FAC loss from baseline levels was not significantly different in the group of bottles not sprayed daily (6% for group 2 at week 5 compared with 7% for Group 4 at week 6). All bottles in Groups 1 and 3 measured by colorimetric strips showed concentrations at or near 5000 mg/L at all weekly time points throughout the experiment. This study shows that 0.5% sodium hypochlorite solutions stored and used in a standard rodent housing room and sprayed daily will maintain acceptable FAC concentrations for at least 5 to 6 wk, perhaps longer. In addition, we report that colorimetric strips may be a useful and accessible quality control tool for testing freshly prepared solutions at regular intervals. We conclude that sodium hypochlorite solutions can be prepared on a weekly, biweekly, or monthly basis with no loss in disinfection effectiveness.

Fluorescence characteristics of E. faecalis in dentine following treatment with oxidizing endodontic irrigants

INTRODUCTION

This study aimed to assess changes in the fluorescence characteristics of Enterococcus faecalis in human dentine over a period of 24 h following treatment with endodontic irrigants.

METHOD

Sterilised, non-functional extracted third molars were embedded in acrylic resin and uniformly sectioned into 2 mm thick dentine sections. After the removal of smear layer, the dentine sections were inoculated with E. faecalis and cultured for 7 days. The infected dentine sections were subsequently treated with different concentrations of sodium hypochlorite (NaOCl) and hydrogen peroxide (H₂O₂). Bacterial fluorescence readings were assessed at different time points using a calibrated laser device. All data were assessed for normality (Kolmogorov Smirnoff test) and analysed using ANOVA with Bonferroni post-hoc tests.

RESULTS

Fluorescence readings were quenched when E. faecalis infected human dentine sections were treated with oxidizing irrigants in vitro. Throughout a 24-hour period, fluorescence recovered in part but did not return to baseline level.

CONCLUSION

The fluorescence quenching effect of these oxidizing agents needs to be considered when using laser fluorescence in assessing the quality of root canal debridement or disinfection.

The influence of biochar and compost mixtures, water content, and gas flow rate, on the continuous adsorption of methane in a fixed bed column

Biofiltration is an excellent alternative for the treatment of diffuse emissions of methane (CH₄) that cannot be treated by physical/chemical means or recovered for energy. Despite the advances on CH₄ biological treatment technologies, they are limited by the low aqueous solubility of CH₄ into the biofilm where CH₄ mineralization occurs. In this study, the CH₄ adsorption kinetics, adsorption capacity and transport behavior of CH₄ was studied in batch experiments and in a fixed-bed column by varying the biochar and compost mixtures under 5-levels, 3 different water contents (dry, 15% and 30% water holding capacity), and 2 inlet flow rates. Experimental results were formally tested using analysis of variance (ANOVA) in order to draw objective conclusions based on statistical inference. As CH₄ biofiltration requires water addition to maintain microbial activity, these results indicate adsorption capacity is not lost with water addition if biochar content is the dominant packing material. The Langmuir isotherm described the data best (R² = 0.99). Maximum adsorption capacity by monolayer adsorption, or q_max, is relatively similar with or without the addition of water as long as the biochar component is the dominant material at 3.5 mg CH₄/g medium for a 7:1 biochar: compost, v/v mixture. Empirical regression models for q_o, k_Th, (Thomas model) and τ and K_YN (Yoon-Nelson model) were developed for the break through curves of CH₄. The current work demonstrates the applicability of utilizing biochar, a relatively inexpensive adsorbent, can compensate for the low solubility of CH₄ and overcome the rate-limiting step of mass transfer from the gas phase and into the methanotrophic biofilm. Further, biochar may be a reliable back-up system for CH₄ storage especially for fluctuating inlet loads that may be encountered in industrial applications adsorbing up to 13 mg CH₄/g biochar under dry conditions.

Efficacy of irrigation tubes in the management of para rectal cavities associated with complex fistula-in-ano

BACKGROUND

Surgical management of complex perianal fistula associated with pararectal cavities can be challenging. We hypothesised that healing of the pararectal cavities prior to healing of the fistula leads to a better outcome. We aimed to assess the efficacy of irrigation catheters in the healing of pararectal cavities associated with fistula-in-ano.

METHODS

This study design was consistent with IDEAL stage 2a (development) and was conducted at the Professorial Surgical Unit, National Hospital of Sri Lanka, Colombo. Thirty-two patients with complex fistulae with a pararectal cavity (detected by 2D-Endoanal ultrasounography-EAUS) were included. All patients underwent examination under anaesthesia (EUA), during which insertion of an irrigation catheter to the pararectal cavity and tagging of the primary fistula tract with a drainage seton was done. Patients were advised to irrigate with antiseptic solution and were followed-up at three weekly intervals to assess cavity reduction.

RESULTS

The majority were males (96.8%, n = 31). The primary fistula tract in 26 patients (81.2%) was trans-sphincteric and was inter-sphincteric in 6 patients (18.7%). Mean time of cavity contraction was 34.78 (range, 21-112) days. Complete healing was seen in 87.5% (n = 28), with 3 patients (9.37%) being lost to follow-up and 1 patient (3.12%) having a persistent perianal fistula after 6 months of follow-up. Those who had complete healing were followed up for a median duration of 6 (range, 3-20) months and there were no recurrences.

CONCLUSIONS

Irrigation in the management of pararectal cavities yielded satisfactory results. A case control trial with larger numbers and assessment of cavity size pre and post procedure by 3D-EAUS/MRI evaluation would be necessary for more objective evaluation of the efficacy of this novel intervention.

Consideration of the Therapeutic Potential of Irrigants in Endodontic Therapy

The main objective of endodontic treatment is to remove vital and necrotic remnants of pulp tissue and microorganisms and their toxic products from the root canal. During chemo-mechanical endodontic preparation, a smear layer is formed on the wall of the canals. Due to an inability to remove all tissue remnants and the smear layer from the root canal by mechanical instrumentation, it is necessary to use irrigation to ensure sufficient cleaning and disinfection of the largest part of the root canalicular system. The most commonly used irrigants are sodium hypochlorite (Na-OCl), ethylenediaminetetraacetic acid (EDTA), citric acid and chlorhexidine (CHX). Recently, the irrigants QMix and MTAD have been introduced to the market. They are a mixture of different components having antimicrobial, organolytic and mineralytic effects on canal detritus and the smear layer. This review article investigates irrigants in terms of the nature of their effect, their efficiency, optimal concentration, and method of use, and the interactions between the irrigants most commonly used in endodontic therapy are discussed, with special emphasis on QMix and MTAD.

Evaluation of pH and Chlorine Content of a Novel Herbal Sodium Hypochlorite for Root Canal Disinfection: An Experimental In vitro Study

INTRODUCTION

Sodium hypochlorite (NaOCl) is widely used endodontic irrigant with its array of advantages and disadvantages. Addition of herbal agents to NaOCl might help in enhancing its efficacy.

MATERIALS AND METHODS

NaOCl was prepared using chlorinated lime, anhydrous sodium carbonate, and distilled water to obtain 6% fresh solution. Then, this solution was evaluated for its pH and chlorine content. The fresh herbal extract of Cymbopogon citratus (lemongrass), Mentha piperita (peppermint), and Ocimum sanctum (tulsi) was prepared from plant leaves. After which, various permutation and combinations were made, and it was found that 9:1 ratio was the most effective combination. The pH and percentage of free chlorine were evaluated and analyzed.

RESULTS

No statistical significant difference was found in pH content. However, significant difference was found between the groups for chlorine content (P < 0.05) of herbal NaOCl.

CONCLUSION

The current study presents a simplified method for preparation of herbal irrigating solution.

Antibacterial activity and safety of commercial veterinary cationic steroid antibiotics and neutral superoxidized water

Antibiotic resistance of bacteria common to the ocular surface is an evolving problem. Thus, novel treatment options with new modes of action are required. We investigated the antibacterial activity and safety of three commercially available topical veterinary ophthalmic products (cationic steroid antibiotics, products A and B, and a neutral superoxidized water, product C) to determine their potential use as antimicrobial alternatives. The minimum inhibitory concentrations (MIC) of the three products were determined against 17 antibiotic resistant bacterial clinical isolates from the ocular surface. Using a standard cytotoxicity assay, the products at varying concentrations were evaluated with a corneal fibroblast cell line and a macrophage-like cell line to determine their potential toxic effect in vitro. The commercial ophthalmic solutions, ofloxacin 0.3%, tobramycin 0.3% and gentamicin 0.3% were used as positive controls for the MIC and tobramycin 0.3% was used as positive control for the cytotoxicity assays. For the MIC, Product C showed no inhibition of growth for any organisms, while Products A and B showed inhibition of growth similar to slightly less than the positive controls. For the cytotoxicity assays, Product C exhibited minimal toxicity while Products A and B exhibited toxicity similar to the controls. In conclusion, Product C had no antibacterial activity in these assays, while Products A and B had antibacterial profiles similar to slightly less than common topical ophthalmic antibiotics and cytotoxicity profiles similar to common topical ophthalmic antibiotics. To our knowledge, this is the first report on the antibacterial activity and safety of the cationic steroid antibiotics and superoxidized water.

Efficacy of chemical disinfectants for the containment of the salamander chytrid fungus Batrachochytrium salamandrivorans

The recently emerged chytrid fungus Batrachochytrium salamandrivorans (Bsal) causes European salamander declines. Proper hygiene protocols including disinfection procedures are crucial to prevent disease transmission. Here, the efficacy of chemical disinfectants in killing Bsal was evaluated. At all tested conditions, Biocidal^®, Chloramine-T^®, Dettol medical^®, Disolol^®, ethanol, F10^®, Hibiscrub^®, potassium permanganate, Safe4^®, sodium hypochlorite, and Virkon S^®, were effective at killing Bsal. Concentrations of 5% sodium chloride or lower, 0.01% peracetic acid and 0.001–1% copper sulphate were inactive against Bsal. None of the conditions tested for hydrogen peroxide affected Bsal viability, while it did kill Batrachochytrium dendrobatidis (Bd). For Bsal, enzymatic breakdown of hydrogen peroxide by catalases and specific morphological features (clustering of sporangia, development of new sporangia within the original sporangium), were identified as fungal factors altering susceptibility to several of the disinfectants tested. Based on the in vitro results we recommend 1% Virkon S^®, 4% sodium hypochlorite and 70% ethanol for disinfecting equipment in the field, lab or captive setting, with a minimal contact time of 5 minutes for 1% Virkon S^® and 1 minute for the latter disinfectants. These conditions not only efficiently target Bsal, but also Bd and Ranavirus.

Pulp revascularization of immature permanent teeth: a review of the literature and a proposal of a new clinical protocol

Tissue engineering is a growing field. In the near future, it will probably be possible to generate a complete vital tooth from a single stem cell. Pulp revascularization is dependent on the ability of residual pulp and apical and periodontal stem cells to differentiate. These cells have the ability to generate a highly vascularized and a conjunctive rich living tissue. This one is able to colonize the available pulp space. Revascularization is a new treatment method for immature necrotic permanent teeth. Up to now, apexification procedures were applied for these teeth, using calcium dihydroxide or MTA to produce an artificial apical barrier. However, the pulp revascularization allows the stimulation of the apical development and the root maturation of immature teeth. Two pulp revascularization techniques are used in the literature, one using calcium dihydroxide and the second using a triple antibiotic paste. Based on these two different pulp revascularization protocols, which obtain the desired therapeutic success, the literature will be reviewed and analyzed according to the relevance of their choice of materials. Based on the literature, we propose a new relevant protocol and a new mixture of antibiotics.

Discoloration of roots caused by residual endodontic intracanal medicaments

AIMS

This study examined the extent to which intervisit corticosteroid-based antibiotic pastes (CAP) medicaments contribute to staining of tooth structure after attempted removal by irrigation techniques.

METHODS

A total of 140 roots were prepared and the canals were filled with Ledermix paste (demeclocycline), Odontopaste (clindamycin), and Doxypaste (doxycycline). The pastes were removed after 2 or 4 weeks of storage in the dark using EDTA and NaOCl with either a 27-gauge-slotted needle or an EndoActivator (Dentsply). The roots were then exposed to an intense light source for 30 minutes each week and photographed after a further 1, 3, or 6 months. Digital images were standardized and data for changes in luminosity were analysed using repeated measures ANOVA and a post hoc test.

RESULTS

Removal of the medicament did not prevent later discolouration. There was no significant difference between the paste removal methods. Ledermix paste caused the greatest darkening compared to the untreated controls, for both application periods and both methods of removal. Doxypaste and Odontopaste caused less darkening than Ledermix.

CONCLUSION

Medicaments that stain teeth may continue to discolour teeth despite best attempts to remove them. This study stresses the importance of material selection and minimising contact of Ledermix within the coronal aspects of teeth.

Endodontic 'solutions' part 1: a literature review on the use of endodontic lubricants, irrigants and medicaments

Endodontic lubricants, irrigants and medicaments help prepare and disinfect root canal systems (RCS) but primary and secondary cases involve different microbes and therefore it is unlikely that one protocol will be effective for both case types. Each individual 'solution' or sequence of'solutions' could play a significant role in each case type, but there are no detailed published guidelines in existence. To help inform clinical practice it was decided to undertake a literature review followed by a UK and Republic of Ireland wide audit on current endodontic'solution' usage within dental schools. The literature review was undertaken under the following headings: pre-op oral rinse; file lubricants; root canal irrigants and intracanal medicaments and provides an evidence base for protocol development for both primary and retreatment cases.The audit project and the protocols developed from the findings of both the literature review and audit will be presented in Part 2.

Transcriptomic response of Escherichia coli O157:H7 to oxidative stress

Chlorinated water is commonly used in industrial operations to wash and sanitize fresh-cut, minimally processed produce. Here we compared 42 human outbreak strains that represented nine distinct Escherichia coli O157:H7 genetic lineages (or clades) for their relative resistance to chlorine treatment. A quantitative measurement of resistance was made by comparing the extension of the lag phase during growth of each strain under exposure to sublethal concentrations of sodium hypochlorite in Luria-Bertani or brain heart infusion broth. Strains in clade 8 showed significantly (P < 0.05) higher resistance to chlorine than strains from other clades of E. coli O157:H7. To further explore how E. coli O157:H7 responds to oxidative stress at transcriptional levels, we analyzed the global gene expression profiles of two strains, TW14359 (clade 8; associated with the 2006 spinach outbreak) and Sakai (clade 1; associated with the 1996 radish sprout outbreak), under sodium hypochlorite or hydrogen peroxide treatment. We found over 380 genes were differentially expressed (more than twofold; P < 0.05) after exposure to low levels of chlorine or hydrogen peroxide. Significantly upregulated genes included several regulatory genes responsive to oxidative stress, genes encoding putative oxidoreductases, and genes associated with cysteine biosynthesis, iron-sulfur cluster assembly, and antibiotic resistance. Identification of E. coli O157:H7 strains with enhanced resistance to chlorine decontamination and analysis of their transcriptomic response to oxidative stress may improve our basic understanding of the survival strategy of this human enteric pathogen on fresh produce during minimal processing.

Shelf-life of a 2.5% sodium hypochlorite solution as determined by arrhenius equation

Accelerated stability tests are indicated to assess, within a short time, the degree of chemical degradation that may affect an active substance, either alone or in a formula, under normal storage conditions. This method is based on increased stress conditions to accelerate the rate of chemical degradation. Based on the equation of the straight line obtained as a function of the reaction order (at 50 and 70 ºC) and using Arrhenius equation, the speed of the reaction was calculated for the temperature of 20 ºC (normal storage conditions). This model of accelerated stability test makes it possible to predict the chemical stability of any active substance at any given moment, as long as the method to quantify the chemical substance is available. As an example of the applicability of Arrhenius equation in accelerated stability tests, a 2.5% sodium hypochlorite solution was analyzed due to its chemical instability. Iodometric titration was used to quantify free residual chlorine in the solutions. Based on data obtained keeping this solution at 50 and 70 ºC, using Arrhenius equation and considering 2.0% of free residual chlorine as the minimum acceptable threshold, the shelf-life was equal to 166 days at 20 ºC. This model, however, makes it possible to calculate shelf-life at any other given temperature.

"Lumpy jaw" in exotic hoof stock: a histopathologic interpretation with a treatment proposal

"Lumpy jaw" of artiodactyls and macropods, although often considered a manifestation of actinomycosis, is actually an osteomyelitis, perhaps commencing with a dental root abscess or trauma to the jaw. Anaerobes may be cultured from the lesions, and vegetable matter may be impacted in them. It is a chronic disease and difficult to treat. Successful treatment may include draining the abscess, cleaning the cavity with saline and antibiotics, flushing with a combination of hydrogen peroxide-sodium hypochlorite and Betadine, and apicoectomy and endodontic filling when active inflammation has subsided.

A survey of sodium hypochlorite use by general dental practitioners and endodontists in Australia

BACKGROUND

Sodium hypochlorite is used commonly as an endodontic irrigant, but there are no published reports that provide details of its use. This survey sought to determine the percentage of Australian dentists who practiced endodontics, whether they used sodium hypochlorite for irrigation, and the manner of dilution, storage and dispensing sodium hypochlorite used by both dentists and endodontists.

METHODS

All Australian endodontists and a stratified random sample of 200 general dentists in Australia were surveyed to address the issues identified above.

RESULTS

Almost 98 per cent of dentists surveyed performed endodontic treatment. Among endodontists, nearly 94 per cent used sodium hypochlorite for irrigation compared with just under 75 per cent of general dentists. Sodium hypochlorite use by general dentists was more common in Victoria and South Australia than in other States. An infant sanitizer (Milton or Johnson's Antibacterial Solution) was used by just over 92 per cent of general practitioners and by more than 67 per cent of endodontists. All other respondents used domestic bleach. One hundred and sixty four of the respondents (80 per cent of endodontists and over 90 per cent of general dentists) used a 1 per cent w/v solution. Ten practitioners used a 4 per cent w/v solution, five used a 2 per cent w/v solution and four used a 1.5 per cent w/v solution. Eighty per cent of the practitioners who diluted their sodium hypochlorite before use, used demineralized water for this purpose. The remainder used tap water. Only four practitioners stored sodium hypochlorite in a manner which risked light exposure and loss of available chlorine content.

CONCLUSIONS

Sodium hypochlorite is commonly used as an endodontic irrigant and Australian dentists generally stored the material correctly.