Low Concentrations Of Hydrogen Peroxide Research Articles

Present status and future directions - Managing discoloured teeth.

Managing tooth discolouration involves a range of different protocols for clinicians and patients in order to achieve an aesthetic result. There is an increasing public awareness in the appearance of their teeth and management of tooth discolouration may be inter-disciplinary and involve both vital and nonvital teeth. Vital teeth can be easily treated with low concentration hydrogen peroxide products safely and effectively using an external approach and trays. For endodontically treated teeth, the walking bleach technique with hydrogen releasing peroxide products is popular. However, there is an association with external cervical root resorption with higher concentrations of hydrogen peroxide of 30%-35%. There are also regulatory considerations for the use of hydrogen peroxide in certain jurisdictions internationally. Prosthodontic treatments are more invasive and involve loss of tooth structure as well as a life cycle of further treatment in the future. This narrative review is based on searches on PubMed and the Cochrane library. Bleaching endodontically treated teeth can be considered a safe and effective protocol in the management of discoloured teeth. However, the association between bleaching and resorption remains unclear although there is likely to be a relation to prior trauma. It is prudent to avoid thermocatalytic approaches and to use a base/sealer to cover the root filling. An awareness expectations of patients and multidisciplinary treatment considerations is important in achieving the aesthetic result for the patient. It is likely that there will be an increasing demand for aesthetic whitening treatments. Bleaching of teeth has also become increasingly regulated although there are international differences in the use and concentration of bleaching agents.

Violet LED-Based Tooth Whitening and Resin Composite Restorations to Reestablish Smile Aesthetics Case Report

This clinical case described the aesthetic treatment of a patient complaining about the aspect of their upper teeth. After anamnesis and clinical examination, the association of tooth whitening photoactivated by violet LED and resin composite restorations was indicated. Prior to restorative treatment, three bleaching sessions were performed with low concentration hydrogen peroxide (6 %; Nano white flex) for 30 minutes. During this period, violet LED irradiation was intercalating performed every 1 minute, totalizing 15 minutes. Ten days after the final bleaching session, old restorations in the upper lateral incisors were removed for better color selection of resin composites. Then, all upper anterior teeth were directly restored with nanofilled resin composite (Filtek Z350XT), reestablishing anatomy, form, and function. At the end of the treatment, the association of techniques proved to be cost-effective, restoring the esthetics satisfactorily and promoting the patient's well-being by a minimally invasive approach.

Mechanically Optimize T Cells Activation by Spiky Nanomotors.

T cell activation is vital for immune response initiation and modulation. Except for the strength of the interaction between T cell receptors (TCR) and peptides on major histocompatibility complex molecules (MHC), mechanical force, mediated by professional mechanosensitive ion channels, contributes to activating T cells. The intrinsic characteristic of synthetic micro/nanomotors that convert diverse energy sources into physical movement and force, opening up new possibilities for T cell regulation. In this work, Pd/Au nanomotors with spiky morphology were fabricated, and in the presence of low concentrations of hydrogen peroxide fuel, the motors exhibited continuous locomotion in the cellular biological environment. Physical cues (force and pressure) generated by the dynamic performance are sensed by mechanosensitive ion channels of T cells and trigger Ca2+ influx and subsequent activation. The successful demonstration that mechanical signals generated in the bio microenvironment can potentiate T cells activation, represents a potential approach for cell-based cancer immunotherapy.

Mild Hyperthermia Induced by Hollow Mesoporous Prussian Blue Nanoparticles in Alliance with a Low Concentration of Hydrogen Peroxide Shows Powerful Antibacterial Effect.

The emergence of superbacteria as well as the drug resistance of the current bacteria gives rise to worry regarding a bacterial pandemic and also calls for the development of novel ways to combat the bacteria. Here in this article, we demonstrate that mild hyperthermia induced by hollow mesoporous Prussian blue nanoparticles (HMPBNPs) in alliance with a low concentration of hydrogen peroxide (H2O2) shows a powerful inhibition effect on bacteria. Our results demonstrate that this therapeutic regime could realize almost full growth inhibition of both Gram-positive (Staphylococcus aureus, S. aureus) and -negative bacteria (Escherichia coli, E. coli), as well as potent inhibition/elimination of the S. aureus biofilm. The wound healing results indicate that combination regime of the antibacterial system could be conveniently used for wound disinfection in vivo and could promote wound healing. To our limited knowledge, this is one of the few pioneer works to apply mild hyperthermia for the combat of bacteria, which provides a novel strategy to inspire future studies.

Injectable Micromotor@Hydrogel System for Antibacterial Therapy.

The drug delivery system based on nano/micromotors has become a research hot spot in recent years. However, naked micromotors may be ruptured or passivated under the complex biological environment, which will result in the leakage of drugs in advance or limited self-propulsion performance. Herein, an injectable micromotor@hydrogel drug delivery system to protect micromotors from the external environment is proposed. The micromotors were prepared through layer-by-layer assembly technology. The asymmetric decomposition of hydrogen peroxide catalyzed by the locally distributed platinum nanoparticles enabled efficient propulsion of the micromotors in low concentration of hydrogen peroxide. In order to protect micromotors, they were loaded into the Schiff base hydrogel. The micromotor@hydrogel system can be injected directly into the lesion to release micromotors in response to the environment, reducing external influence on micromotors and improving the sustained-release effect. Erythromycin (Ery) loaded into the micromotors and the micromotor@hydrogel system demonstrated excellent antibacterial effect. Micromotors released from the hydrogel underwent enhanced diffusion in the surroundings of bacteria without addition of exogenous hydrogen peroxide, which was manifested by their appearance in edge of the inhibition zone. The proposed micromotor@hydrogel drug delivery system offers a new strategy for the treatment of bacterial infections.

A palladium polyaniline complex: a simple and efficient catalyst for batch and flow Suzuki-Miyaura cross-couplings.

A novel palladium polyaniline complex (Pd@PANI) was synthesized via a one-pot method using a low concentration of hydrogen peroxide (3 wt%) as a mild oxidant. Pd@PANI was employed to catalyze Suzuki-Miyaura cross-couplings with 0.11 ppm levels of palladium and high turnover numbers (up to 6.1 × 104). Various aromatic halides and aromatic boric acids were used as reaction partners to prepare the biaryl compounds in high yields. Application of the method in the synthesis of D-fructose derivatives was also performed. Furthermore, the catalyst was evaluated under a flow process to provide the corresponding products in good yields with shorter residence times and lower temperatures in more convenient operations compared with the batch conditions.

In situ fabrication of metal-organic framework derived hybrid nanozymes for enhanced nanozyme-photothermal therapy of bacteria-infected wounds

In recent years, nanozyme-photothermal therapy (NPT) has attracted enormous interests owing to their enhanced therapeutic effects and less adverse effects in the treatment of infectious diseases. However, the development of nanozyme-photothermal agents (NPAs) that can rapidly, efficiently and synergistically combating pathogenic bacteria remains a huge challenge due to the limitation of size effect. Herein, by decorating platinum nanozymes on Zn-based photosensitizer, we report a novel metal-organic framework (MOF)-derived hybrid nanozymes antibacterial strategy for enhanced NPT. This strategy can not only prevent the aggregation of platinum nanozymes and effectively reduce the mass transfer resistance during the kinetic reaction, but also inhibit the photoelectron-hole recombination in the process of photothermal therapy (PTT) and improve the photothermal conversion performance. In the presence of a low concentration of hydrogen peroxide (H 2 O 2 ), the superior nanocatalytic activity of the MOF-derived hybrid nanozymes can effectively catalyze the release of H 2 O 2 to generate toxic hydroxyl radical (•OH), resulting in the increase of bacterial membrane permeability and thermal sensitivity. Once the near-infrared laser is introduced, the nanozyme-photothermal antibacterial platform can play the role of “nanoknife” to further induce the death of the damaged bacteria by physical cutting. In vitro and vivo in antibacterial assays confirm that the MOF-derived hybrid nanozymes have excellent antibacterial properties, which can serve as an antibacterial candidate with negligible adverse effect. Therefore, this work will open a new avenue for MOF-derived hybrid nanozymes in biomedical application. • The MOF-derived hybrid nanozymes antibacterial strategy was used to enhance the nanozyme-photothermal therapy. • The PEG@Zn/Pt–CN nanozyme-photothermal antibacterial platform processed excellent ROS-released and NIR-responsive property. • The PEG@Zn/Pt–CN nanozyme-photothermal antibacterial platform could kill 98.74% E. coli and 99.63% S. aureus. • Wound infection model experiments confirmed the antibacterial activity and the rapid tissue repair effect.

Flame-Holding Characteristics of a Hybrid Rocket using Pre-heated 60wt% Hydrogen Peroxide

As the number of micro-deep space probes launched by large rockets using the piggyback increases, the demand for safe, low-cost, re-ignitable, and high-thrust kick motors for efficient inter-orbit satellite transfer is expected to increase as well. Low-concentration hydrogen peroxide is the most suitable oxidizer for hybrid kick motors for micro-spacecraft in terms of safety, low cost, and ease of storage. However, it has difficulty in ignitability and flame holding due to its high water content. In this study, we considered a method to decompose low-concentration hydrogen peroxide by external heating using a heat exchanger before supplying it to a CAMUI-type fuel. A ground combustion experiment showed that flame holding was successfully achieved, however, there were vibrations in the combustion chamber pressure. In order to obtain the lower limit of the heating required for stable combustion, we plan to evaluate the flame holding limit and calculate the heat input to the hydrogen peroxide.

Causes and Management of Tooth Discoloration: A Review

Tooth discoloration is a common dental occurrence that is linked to both clinical and aesthetic issues. The treatment of tooth discoloration has grown into highly complex, scientific, and therapeutic field by the twenty-first century. Dental surgeons must understand the etiology of tooth staining in order to provide an accurate diagnosis and thus management. Extrinsic causes produce tooth darkening, whereas intrinsic congenital or systemic influences cause tooth discoloration. Tooth bleaching is a safe and effective way to lighten the color of the teeth. Today, the physician has a number of options, including at-home tray-based bleaching treatments with low hydrogen peroxide or carbamide peroxide concentrations. Surgical options include dental restorations which is may be indicated for some cases. This review aims to summarize current evidence regarding causes, classification and management of tooth discoloration. Medline and PubMed public database searches were carried out for papers written all over the world on tooth discoloration. No predictive analytics technology was used.

Innovative method of utilising hydrogen peroxide for source water management of cyanobacteria.

The treatment and control of cyanobacterial blooms using copper-based algaecides in water reservoirs have historically been used; however, due to the adverse impact of copper on the environment, water authorities have been researching and studying new and innovative ways to control cyanobacterial blooms. Hydrogen peroxide has been investigated as an environmentally friendly alternative, and this research aims to determine the impact of water quality on its effectiveness based on the decay characteristics in different water samples. Natural water samples from South Australian reservoirs and riverwere used to evaluate hydrogen peroxide decomposition and provide a better strategy for water operators in using it as an algaecide. Our experiments show the dependency of hydrogen peroxide decomposition not only on water quality but also on the initial hydrogen peroxide dose. A higher initial hydrogen peroxide dose can trigger the increase of pH, leading to increased consumption of hydrogen peroxide. In addition, the hydrogen peroxide decomposition is significantly accelerated with the rise of copper concentration in water samples. Moreover, it is found that UV light can also affect the decomposition rate of hydrogen peroxide. The hydrogen peroxide decay is more significant under UV light for the samples with lower hydrogen peroxide concentrations. Our study also shows the impact of dissolved organic carbon (DOC) on hydrogen peroxide decomposition is not substantial. The study also presents a modelling method to optimise hydrogen peroxide application based on water quality characteristics. Our findings can provide knowledge for the water industry to produce a suitable model which can be used to optimise the application of hydrogen peroxide for the control of cyanobacteria.

Low concentration hydrogen peroxide decomposition inside a minichannel with annual silver catalyst

Hydrogen peroxide is a green propellant which apart from space propulsion is used in various industrial applications. Though hydrazine was used initially, the nature of hydrazine which is a toxic, carcinogenic and hazardous fuel resulted in various space agencies’ interest in green propellants. The essential step for high test peroxide (HTP) as a green mono propellant realization is on development of a reliable, effective, long life catalytic beds which are not affected by catalytic poisoning and impurities. In the present study, a 3D model is developed using COMSOL Multiphysics software to know the catalytic decomposition of 30% hydrogen peroxide flowing inside a 3 mm diameter 300 mm length channel. The effect of annular silver catalyst (I.D – 1.6 mm, O.D. – 2 mm, length 10 mm) on decomposition rate is studied in detail. The positioning of silver catalyst bed and number of beds increased the reaction rate with varying pressure drop. Among the variations simulated, the 4 catalyst model gives the better performance and gets decomposed to a greater extent. This model will help in the design of a micro thruster which can operate efficiently with low pressure drop.

Preconditioning of bull semen with sub-lethal oxidative stress before cryopreservation: Possible mechanism of mitochondrial uncoupling protein 2

Preconditioning of sperm using sub-lethal oxidative stress before cryopreservation is an innovative approach that can improve sperm cryo-survival. Mitochondrial uncoupling proteins (UCPs) are critical in reducing ROS level during stress conditions. The aim of the current study was to investigate whether mild sub-lethal stress induced by low concentrations of nitric oxide and hydrogen peroxide has a protective effect on quality parameters of post–thaw bull semen through modulations of mitochondrial uncoupling protein 2 (UCP2) expression. Semen samples were collected from 6 mature Holstein bulls, then mixed and divided into 8 aliquots: fresh, frozen control and frozen groups treated with NO: 0.1 (NO-0.1), 1(NO-1), 10 μM (NO-10), and H2O2: 0.1(H2O2-0.1), 1(H2O2-1) and 10μM (H2O2-10). A significantly higher percentage of total motility, progressive motility and viability was observed in NO-1 and H2O2-10 compared to the other frozen groups (P < 0.05). Sperm exposed to 1 μM NO and 10μM H2O2 showed significantly increased percentages of mitochondria activity and membrane integrity (P < 0.05). Moreover, the lowest percentage of apoptotic percentage was observed in the NO-1 and H2O2-10 in comparison to the other frozen groups. In addition, the expression level of UCP2 was higher in the NO-1 and H2O2-10 compared to the other groups (P < 0.05). It can be concluded that stress preconditioning of bull sperm before cryopreservation can increase UCP2 expression of sperm, that can play a protective role against cryoinjury after thawing.

Assessment of Occlusal Force and Local Gas Release Using Degradable Bacterial Cellulose/Ti3C2Tx MXene Bioaerogel for Oral Healthcare.

Dental diseases resulting from movement disorders and volatile gases are very common. The classic method for detecting occlusal force is effective; however, its function is one-time rather than real-time monitoring, and the technology is very time-consuming. Herein, we report a multifunctional, flexible, and degradable bacterial cellulose/Ti3C2Tx MXene bioaerogel for the accurate detection of occlusal force and early diagnosis of periodontal diseases. Combining the mechanical properties of MXene and the abundant functional groups of bacterial cellulose, 3D porous bioaerogels exhibit both pressure-sensitive and ammonia (NH3)-sensitive responses. By integrating these substances into a flexible array, the resulting device can distinguish the intensity, location, and even the time sequence of the occlusion force; moreover, it can provide NH3 gas and occlusion force response signals. Therefore, this technology is promising for both disease diagnosis and oral health. In addition, the introduction of a renewable biomaterial allows the bioaerogel to degrade completely using a low-concentration hydrogen peroxide solution, making the device environmentally friendly and satisfying the demands for sustainable development.

Effects of Sequential Hydrogen Peroxide Applications on Salt Stress Tolerance in Bread Wheat Varieties

Salinity is affecting plant growth and development. Low concentration of hydrogen peroxide (H2O2) has shown to be effective against various stress factors. In this study, effect of different H2O2 priming methods on growth, physiological and biochemical parameters in three wheat varieties (NKÜ Lider, Sultan-95, and Tosunbey) under salt stress were investigated. Salt stress (0 and 160 mM NaCl) was applied gradually to 100 µM H2O2 applied (-H2O2: negative control, no application; H2O2: positive control, 100 μM H2O2 applied; 1xH2O2: 100 μM H2O2 applied one year ago; 2xH2O2: 100 μM H2O2 applied second time after one year) wheat seedlings. Biochemical results showed that the lowest H2O2 level was in NKÜ Lider variety and in -H2O2 and 1xH2O2 groups. The lowest thiobarbituric acid reactive substances (TBARS) level was in Tosunbey variety and 2xH2O2 group. The highest superoxide dismutase (SOD) activity was in NKÜ Lider variety, all H2O2 pre-treatment caused an increase in SOD activity and 2xH2O2 pre-treatment caused the highest SOD activity. However, H2O2 and TBARS levels increased in all application groups except 2xH2O2 group, while the H2O2 amount increased and TBARS level decreased in 2xH2O2 group. MnSOD was not detected in any groups. CuZnSOD increased in all groups except 2xH2O2 groups under salt stress in Sultan-95 variety compared to FeSOD. H2O2 pre-treatment better tolerated salt stress, and second-applied H2O2 pre-treatment eliminated the stress and improved plant growth. In conclusion, it was determined that H2O2 re-pre-treatment to wheat seeds resulted in improvement of plant growth in tolerant varieties exposed to salt stress.

A New Clark-Type Layered Double Hydroxides-Enzyme Biosensor for H2O2 Determination in Highly Diluted Real Matrices: Milk and Cosmetics

A new catalase amperometric biosensor for hydroperoxides detection has been built as part of research aimed at the development of biosensors based on layered double hydroxides (LDH) used as support for enzyme immobilization. The fabricated device differs from those developed so far, usually based on an LDH enzyme nanocomposite adsorbed on a glassy carbon (GC) electrode and cross-linked by glutaraldehyde, since it is based on an amperometric gas diffusion electrode (Clark type) instead of a GC electrode. The new biosensor, which still uses LDH synthesized by us and catalase enzyme, is robust and compact, shows a lower LOD (limit of detection) value and a linearity range shifted at lower concentrations than direct amperometric GC biosensor, but above all, it is not affected by turbidity or emulsions, or by the presence of possible soluble species, which are reduced to the cathode at the same redox potential. This made it possible to carry out accurate and efficient determination of H2O2 even in complex or cloudy real matrices, also containing very low concentrations of hydrogen peroxide, such as milk and cosmetic products, i.e., matrices that would have been impossible to analyze otherwise, using conventional biosensors based on a GC–LDH enzyme. An inaccuracy ≤ 7.7% for cosmetic samples and ≤8.0% for milk samples and a precision between 0.7 and 1.5 (as RSD%), according to cosmetic or milk samples analyzed, were achieved.

Polymorphic variants of glutathione reductase - new genetic markers of predisposition to type 2 diabetes mellitus

To study the associations of three common single nucleotide variants of the gene encoding antioxidant system enzyme, glutathione reductase GSR with a predisposition to type 2 diabetes (T2D). The observational mono-center transverse controlled study involved 1032 type 2 diabetics (640 women, 392 men; mean age 61.14.8 years) and 1056 healthy volunteers (676 women, 380 men; mean age 60.96.2 years). Eating habits were evaluated retrospectively according to questionnaire data. A 10 ml blood sample was drawn from all participants in the study for genetic and biochemical tests. Genotyping was done with the use of the iPLEX technology on MassArray System. We first identified the relationship of the polymorphisms rs2551715, rs2911678, rs3757918 of the GSR gene with a reduced risk of developing T2D in the Russian population. At the same time, the protective effects of the variants of the glutathione reductase gene manifested only in individuals with normal body weight provided they consumed fresh vegetables and fruits, whereas in those with insufficient consumption of plant foods, as well as in all overweight and obese patients, the protective effect of GSR was not observed. In patients with T2D, the plasma levels of hydrogen peroxide and the glutathione dimer were sharply increased compared with the controls. We also found that the rs2551715 polymorphism was associated with a lower concentration of hydrogen peroxide in the blood plasma of patients with T2D, while SNP rs2911678 was associated with a decrease in the concentration of the oxidized form of glutathione. Bioinformatical analysis confirmed the positive effect of alternative alleles on GSR expression and revealed the closest protein partners of the enzyme and their joint participation in the metabolism of acetyl-CoA, the catabolism of hydrogen peroxide and the control of cellular redox homeostasis. Polymorphic variants of the GSR gene rs2551715, rs2911678, rs3757918 are associated with a predisposition to T2D, but their relationship with the disease is modulated by the consumption of fresh vegetables and fruits and depends on body mass index.

Organic Hydroperoxide Resistance Gene ohr (VPA1681) Confers Protection against Organic Peroxides in the Presence of Alkyl Hydroperoxide Reductase Genes in Vibrio parahaemolyticus.

The marine foodborne enteropathogen Vibrio parahaemolyticus contains the chief organic peroxide reductases AphC1-AhpC2 and a putative organic hydroperoxide resistance enzyme (Ohr; VPA1681) against different peroxides. This study investigated the function of the Ohr under the presence of AhpC1-AhpC2 in this pathogen by gene mutation. Experimental results demonstrated that the ohr gene product was a weak scavenger of H2O2 only in the mutant strains that lacked the peroxide sensor/regulator oxyR and ahpC1-ahpC2 genes. The Ohr of V. parahaemolyticus was highly effective at scavenging organic peroxide, as demonstrated by assaying the defective changes in the Δohr mutant strain and determining the detoxifying activity of the purified recombinant V. parahaemolyticus Ohrvp protein in the reduced form. The Ohr and AhpC1-AhpC2 exhibited similar functions against organic peroxides; however, only the ΔahpC1ΔahpC2 mutant strain showed a significant increase in susceptibility to several disinfectants, organic acids, and antibiotics compared with the wild-type strain. The transcription of the ohr gene depended on exogenous cumene hydroperoxide (cumene) stress and was markedly enhanced in the ΔohrR (VPA1682) mutant strains. This study revealed the organic hydroperoxide reductase activity of the Ohr in V. parahaemolyticus, and its role probably depends on sophisticated regulation by OhrR. IMPORTANCE Vibrio parahaemolyticus is the most prevalent foodborne pathogen in Taiwan and some other coastal Asian countries, and its antioxidative activity contributes to the tolerance of this bacterium to different environmental stresses. This study reports on the function of the organic hydroperoxide resistance gene (ohr; VPA1681) and its gene regulator, ohrR (VPA1682), in this pathogen. The strain with the ohr gene had effective protection against organic peroxide, and the recombinant Ohrvp was active in its reduced form. The function of Ohr was significant mostly in strains in which the function of AhpC1-AhpC2 was limited. The ohrR repressor of the ohr gene was effective at low concentrations of organic peroxide. Other common Vibrio species that contain homologous ohr, ohrR, ahpC1, and ahpC2 genes, which are phylogenetically close to those of V. parahaemolyticus, may share similar functions to those revealed in this study.

Gastric antrum stenosis caused by accidental ingestion of concentrated hydrogen peroxide.

Hydrogen peroxide (HP) is an oxidizing agent that has since long been used for medical purposes, such as wound irrigation, dental irrigation, and enema. However, its routine use is limited by many toxic effects such as portal gas embolism1 and proctitis.2 Accidental ingestion of concentrated HP is not common and has been reported to cause an extensive portal gas embolism, esophagitis, gastritis,3 and even result in death. However, reports of gastric corpus stenosis caused by accidental ingestion of HP are rare. A 60-year-old man ingested a mouthful of HP (30%), thinking it was water after a family member filled the water jar with HP on February 23, 2020, when most households in the region used HP as a disinfectant because of the Covid-19 pandemic. He felt epigastric pain, burning sensation in the chest area, had attacks of persistent vomiting, and non-bloody foaming in the mouth and was immediately presented to a county hospital 30 min later. Upon arrival to the emergency department, his vital signs were stable, the abdomen was soft but tender, and he was neurologically intact. A computerized tomography scan of the abdomen was performed and revealed gas in the portal vein throughout the liver (Fig. 1). After gastric lavage, the patient's symptoms were not relieved, and then he was transferred to a provincial hospital. The patient was then treated with proton pump inhibitors and parenteral nutrition for more than 2 months and was allowed a liquid diet (less than 100 ml). He felt abdominal distension, repeatedly vomited white sticky gastric juice, and lost 11 kg weight. Endoscopy was performed on April 27, demonstrating cardiac stenosis, esophagitis, diffuse gastritis with multiple petechiae, and white exudate; gastric stenosis (Fig. 2) and gastroenterography performed on May 27 revealed gastric antrum stenosis and gastric retention. Jejunostomy was performed on May 12, and the patient was treated with continuous enteral nutrition, which provided 2000 kcal daily, through a jejunostomy tube for the following 3 months, and he gained 5 kg weight. The patient was then readmitted, and gastroenterography (Fig. 3) performed on September 6 indicated gastric retention and gastric antrum stenosis, so gastrojejunostomy (Roux-en-Y) was performed on September 22. The patient was discharged on October 9, when he recovered to a regular diet. The patient remained well during 3 months follow-up. The three main mechanisms involved in HP toxicity damage include oxygen gas formation, corrosive damage, and lipid peroxidation.4 The toxic effect of HP seems to be related to the ingested concentration and quantity. Ingestion of low concentration of HP (3%) has been reported to be usually asymptomatic or resulted in mild symptoms such as nausea and vomiting.5 Complications such as gastritis, hemorrhagic gastritis, gastric ulcers, and gas in the portal vein have also been reported.1-3 Accidental ingestion of concentrated HP (35%) is more likely to result in serious complications such as hemorrhagic gastritis, portal venous gas embolism, acute myocardial infarction, neurological impairment, and death.1, 4, 6-8 Our patient presented with a rare case of accidental ingestion of HP associated with the portal vein gas embolism, gastritis, and gastric antrum stenosis, which hindered the patient's intake of food and resulted in malnutrition. Waiting for a certain period before the surgical treatment of gastric antral stenosis is recommended because the stabilization of the pathological process of gastric injury takes time. Accordingly, appropriate nutrition methods should be adopted to maintain the nutrition of patients during the waiting period. All data generated appear in the submitted article. Shi-lian Le: Data curation; supervision; writing – review and editing. Long-xin Xiong: Resources; validation; writing – review and editing. Peng Deng: Formal analysis; project administration; writing – original draft; writing – review and editing.

Evaluation of Tooth Sensitivity of In-office Bleaching with Different Light Activation Sources: A Systematic Review and a Network Meta-analysis.

A systematic review and network meta-analysis were performed to answer the following research question: Are there differences in the risk and the intensity of tooth sensitivity (TS) among eight light activation systems for in-office bleaching in adults? Randomized controlled trials (RCTs) that compared at least two different in-office bleaching light activations were included. The risk of bias (RoB) was evaluated with the RoB tool version 1.0 from the Cochrane Collaboration tool. A random-effects Bayesian mixed treatment comparison (MTC) model was used independently for high- and low-concentration hydrogen peroxide. The certainty of the evidence was evaluated using the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) approach. A comprehensive search was performed in PubMed, Bridge Base Online (BBO), Latin American and Caribbean Health Sciences Literature database (LILACS), Cochrane Library, Scopus, Web of Science, and grey literature without date and language restrictions on April 23, 2017 (updated on September 26, 2019). Dissertations and theses, unpublished and ongoing trials registries, and IADR (International Association for Dental Research) abstracts (2001-2019) were also searched. After title and abstract screening and the removal of duplicates, 32 studies remained. Six were considered to be at low RoB, three had high RoB, and the remaining had an unclear RoB. The MTC analysis showed no significant differences among the treatments in each network. In general, the certainty of the evidence was graded as low due to unclear RoB and imprecision. There is no evidence that the risk and intensity of TS are affected by light activation during in-office bleaching.

IMPROVED QUANTITATION OF LOW PEROXIDE VALUE IN HIGHLY REFINED OIL INTENDED FOR USE DURING EMBRYO CULTURE USING A COMMERCIALLY AVAILABLE METHOD

The objective is to evaluate whether the peroxide value (POV) determination method of an oil intended for use for embryo culture can be optimized for precise quantitation of low concentrations of peroxide.