Calcium hypochlorite cytotoxicity mechanism in fibroblasts and effect on osteoblast mineralization.

AIM: To determine the cytotoxicity mechanism of 2.5% calcium hypochlorite [Ca(OCl)2 ] in L929 fibroblasts and the effect of this solution on human osteoblast-like cells (Saos-2) mineralization, compared to that of 2.5% sodium hypochlorite (NaOCl). METHODOLOGY: L929 fibroblasts were exposed to Ca(OCl)2 and NaOCl at different dilutions for 10 min. Cell metabolism was assessed by methyl-thiazole-tetrazolium (MTT); lysosome integrity, by neutral red (NR) assay; type of cell death, by flow cytometry (apoptosis/necrosis); cytoskeleton, by actin and α-tubulin fluorescence and cell ultrastructure, by transmission electron microscopy (TEM). The alkaline phosphatase (ALP) activity and mineralized nodule formation were determined in Saos-2 by thymolphthalein release and alizarin red staining (ARS), respectively. The data were analysed by two-way anova and Bonferroni's post-test (α = .05). RESULTS: Ca(OCl)2 promoted higher cell viability and a lower percentage of apoptosis and necrosis than NaOCl (p < .05). Ca(OCl)2 and NaOCl decreased cell metabolism and lysosome integrity, induced the breakdown of microtubules and actin filaments, promoted alterations of rough endoplasmic reticulum and disruption of mitochondrial cristae. Additionally, Ca(OCl)2 did not induce ALP activity and had no effect on mineralized nodules formation. CONCLUSIONS: Although Ca(OCl)2 and NaOCl promoted the same cytotoxicity mechanism, Ca(OCl)2 was less cytotoxic than NaOCl. As for ALP activity, no differences were observed between NaOCl and Ca(OCl)2 . The production of mineralized nodules induced by Ca(OCl)2 was lower than those induced by NaOCl, but was not different from those induced by the control group.

Mitigation of graphene oxide toxicity in C. elegans after chemical degradation with sodium hypochlorite.

Graphene oxide (GO) is a promising and strategic carbon-based nanomaterial for innovative and disruptive technologies. It is therefore essential to address its environmental health and safety aspects. In this work, we evaluated the chemical degradation of graphene oxide by sodium hypochlorite (NaClO, bleach water) and its consequences over toxicity, on the nematode Caenorhabditis elegans. The morphological, chemical, and structural properties of GO and its degraded product, termed NaClO-GO, were characterized, exploring an integrated approach. After the chemical degradation of GO at room temperature, its flake size was reduced from 156 to 29 nm, while NaClO-GO showed changes in UV-vis absorption, and an increase in the amount of oxygenated surface groups, which dramatically improved its colloidal stability in moderately hard reconstituted water (EPA medium). Acute and chronic exposure endpoints (survival, growth, fertility, and reproduction) were monitored to evaluate material toxicities. NaClO-GO presented lower toxicity at all endpoints. For example, an increase of over 100% in nematode survival was verified for the degraded material when compared to GO at 10 mg L-1. Additionally, enhanced dark-field hyperspectral microscopy confirmed the oral uptake of both materials by C. elegans. Finally, this work represents a new contribution toward a better understanding of the links between the transformation of graphene-based materials and nanotoxicity effects (mitigation), which is mandatory for the safety improvements that are required to maximize nanotechnological benefits to society.

Assessment of toxicity and oxidative DNA damage of sodium hypochlorite, chitosan and propolis on fibroblast cells.

The objective of this study was to evaluate and compare the cytotoxicity and genotoxicity on human fibroblast cell lines of sodium hypochlorite (NaOCl), chitosan and propolis as root canal irrigating solutions. Human fibroblast cells were exposed to chitosan, propolis and NaOCl for 4 and 24 h. Cell viability was assessed by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide, and oxidative DNA damage was assessed by determination of 8-hydroxydeoxyguanosine (8-OHdG) level with an ELISA kit. The data of cell cytotoxicity were analysed statistically using a test of one-way analysis of variance at a significance level of p < 0.05. In the NaOCI group, the 8-OHdG level was higher than in the chitosan group, but there was no statistical difference when compared with the other groups (p < 0.05). It was determined that the irrigation solutions were cytotoxic, depending on the dose and time. NaOCl was the most toxic solution after both 4 and 24 h of exposure (p < 0.05). Chitosan and propolis may be alternatives to NaOCl for irrigation solutions, because they are both less toxic and produce less oxidative DNA damage.

Antimicrobial and cytotoxic effects of denture base acrylic resin impregnated with cleaning agents after long-term immersion.

The coadjutant method for denture cleansing most used by denture wearers is immersion in chemical agents, which are toxic when in direct contact with cells. However, clinically, the contact between these chemical agents and prosthetic tissues does not occur directly, but rather with what remained impregnated into acrylic bases, even after rinsing the disinfected dentures. This study evaluated the antimicrobial and cytotoxic effects of a denture acrylic resin after successive cycles of daily overnight immersion in 1% sodium hypochlorite (1%NaClO) and 2% chlorhexidine digluconate (2%CHX), simulating the periods of 9 months or 1.5 year. Microbiological and cytotoxic assays were performed, respectively, by broth microdilution method (Candida albicans or Staphylococcus aureus) and MTT assay. Chemical residues of 2%CHX impregnated into the denture acrylic resin had an antimicrobial effect on both immersion periods, which was not observed with those of 1%NaClO. However, residues of 2%CHX were severely cytotoxic to human gingival fibroblasts compared to those of 1%NaClO and acrylic resin (not submitted to the denture cleansers), which were slightly cytotoxic. Even at low concentrations recommended for overnight soaking of removable dentures, the chemical residues of CHX may result in some degree of toxicity to the denture-bearing mucosa after long-term daily immersion.

Cytotoxic potential of denture base and reline acrylic resins after immersion in disinfectant solutions.

STATEMENT OF PROBLEM: The daily immersion of dentures in disinfectant solutions can cause the incorporation of toxic substances in the acrylic resins, and studies evaluating the cumulative effect of disinfectant solutions on cell culture are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the cytotoxic potential of cell cultures of denture base and reline acrylic resins after immersion in disinfectant solutions. MATERIAL AND METHODS: Disk-shaped specimens (14×1.2 mm) were obtained and divided into groups (n=9) according to the disinfectant solutions (distilled water [control], 2% chlorhexidine digluconate, 3.8% sodium perborate, 0.5% sodium hypochlorite, and apple vinegar) and to the storage period (0, 1, 3, and 6 months). Solutions were changed daily. After the different storage periods, specimens were immersed in culture medium for 24 hours, and extracts were obtained. Human keratinocytes were cultivated, and the cellular metabolism was evaluated by using Alamar Blue. Data were submitted to 3-way analysis of variance and Games-Howell post hoc tests (α=.05). RESULTS: Both of the acrylic resins tested showed similar biocompatibility properties after immersion in different solutions (P=.400). Immersion in distilled water, 3.8% sodium perborate, and 0.5% sodium hypochlorite did not affect the cellular metabolism of the keratinocytes (P>.05), regardless of the immersion period and the type of acrylic resin (P>.05). Immersion in 2% chlorhexidine digluconate or apple vinegar resulted in high cytotoxicity over time, until the third month (P<.05), after which no changes were observed (P>.05). CONCLUSIONS: The type of acrylic resin (base or reline) had no significant effect on the viability of cells. Vinegar and chlorhexidine digluconate solutions increased in cytotoxic effect over time, and were strongly cytotoxic after 6 months of immersion. Sodium perborate and sodium hypochlorite were noncytotoxic in all periods of time tested.

Cytotoxicity of peracetic acid: evaluation of effects on metabolism, structure and cell death.

AIM: To evaluate the cytotoxicity and the mechanism of cell aggression of peracetic acid (PA) in comparison with sodium hypochlorite (NaOCl). METHODOLOGY: L929 fibroblasts were exposed to 1% PA and 2.5% NaOCl, at several dilutions for 10 min. The following parameters were evaluated: cell metabolism by methylthiazol tetrazolium assay, external morphology by scanning electron microscopy, ultrastructure by transmission electron microscopy, the cytoskeleton by means of actin and α-tubulin labelling, and the type of cell death by flow cytometry (apoptosis/necrosis). The data were analysed by two-way anova and the Bonferroni post-test (α = 0.05). RESULTS: The PA group had lower cell viability and a higher percentage of necrotic cells than the NaOCl group (P < 0.05). Both solutions diminished cell metabolism, led to destructuring of the cytoskeleton, created changes in the external morphology, resulted in the accumulation of proteins in the rough endoplasmic reticulum and induced cell death predominantly by necrosis. However, these changes were observed in lower doses of PA when compared with NaOCl. CONCLUSIONS: Although they had the same mechanism of cytotoxicity, 1% PA had greater cytotoxic potential than 2.5% NaOCl.

Assessment of toxicity and oxidative DNA damage of sodium hypochlorite, chitosan and propolis on fibroblast cells

Abstract The objective of this study was to evaluate and compare the cytotoxicity and genotoxicity on human fibroblast cell lines of sodium hypochlorite (NaOCl), chitosan and propolis as root canal irrigating solutions. Human fibroblast cells were exposed to chitosan, propolis and NaOCl for 4 and 24 h. Cell viability was assessed by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide, and oxidative DNA damage was assessed by determination of 8-hydroxydeoxyguanosine (8-OHdG) level with an ELISA kit. The data of cell cytotoxicity were analysed statistically using a test of one-way analysis of variance at a significance level of p < 0.05. In the NaOCI group, the 8-OHdG level was higher than in the chitosan group, but there was no statistical difference when compared with the other groups (p < 0.05). It was determined that the irrigation solutions were cytotoxic, depending on the dose and time. NaOCl was the most toxic solution after both 4 and 24 h of exposure (p < 0.05). Chitosan and propolis may be alternatives to NaOCl for irrigation solutions, because they are both less toxic and produce less oxidative DNA damage.

Use of a 660-nm Laser to Aid in the Healing of Necrotic Alveolar Mucosa Caused by Extruded Sodium Hypochlorite: A Case Report.

The extrusion of sodium hypochlorite through the apical foramen is an accident that can occur during the flushing procedure in endodontic treatment. The symptomatology is immediate and intense, and there is a long period before the tissues return to normal. Low-level laser therapy might be useful as an adjunctive treatment for damaged soft tissues because of its anti-inflammatory and analgesic effects, which may reduce edema and prevent infection. In this clinical case, the accidental leakage of 1% sodium hypochlorite during the preparation of the root canal of a maxillary right central incisor is reported. This leakage caused immediate and intense pain and edema formation and resulted in an extensive necrotic area in the alveolar mucosa adjacent to the root of the treated tooth. The conventional treatment protocol was combined with low-level laser therapy. Clinical and radiographic examinations after 7 months revealed complete repair of the necrotic area with no paresthesia and further indicated the integrity of the apical region of the tooth where the extrusion of sodium hypochlorite occurred. The combination of low-level laser therapy with a conventional treatment protocol in this case of the extrusion of 1% sodium hypochlorite resulted in the healing of the wounds.

NSAID-manufacturing plant effluent induces geno- and cytotoxicity in common carp (Cyprinus carpio).

The pharmaceutical industry generates wastewater discharges of varying characteristics and contaminant concentrations depending on the nature of the production process. The main chemicals present in these effluents are solvents, detergents, disinfectants - such as sodium hypochlorite (NaClO) - and pharmaceutical products, all of which are potentially ecotoxic. Therefore, this study aimed to evaluate the geno- and cytotoxicity induced in the common carp Cyprinus carpio by the effluent emanating from a nonsteroidal anti-inflammatory drug (NSAID)-manufacturing plant. Carp were exposed to the lowest observed adverse effect level (LOAEL, 0.1173%) for 12, 24, 48, 72 and 96 h, and biomarkers of genotoxicity (comet assay and micronucleus test) and cytotoxicity (caspase-3 activity and TUNEL assay) were evaluated. A significant increase with respect to the control group (p<0.05) occurred with all biomarkers from 24h on. Significant positive correlations were found between NSAID concentrations and biomarkers of geno- and cytotoxicity, as well as among geno- and cytotoxicity biomarkers. In conclusion, exposure to this industrial effluent induces geno- and cytotoxicity in blood of C. carpio.

Bactericidia de hipoclorito de sodio sobre Staphylococcus cohnii productor de biofilm en una fabrica / Bactericidal activity of sodium hypochlorite against biofilm-producing Staphylococcus cohnii in a factory / Atividade bactericida de hipoclorito de sodio sobre Staphylococcus cohnii produtor de biofilme numa fabrica

En equipamientos industriales la persistencia de las bacterias se debe al desarrollo de biofilms. El hipoclorito de sodio (NaClO) es usado rutinariamente como desinfectante. El objetivo del trabajo fue determinar el efecto inhibitorio del NaClO sobre S. cohnii productoras y no productoras de biofilms aisladas de una fabrica de pastas a partir de maquinarias de un establecimiento de Tucuman, Argentina. Se estudio produccion de biofilm, concentracion inhibitoria minima (CIM), concentracion bactericida minima (CBM) y curva de tiempo de muerte con NaClO frente a S. cohnii productora y no productora de biofilm. Los resultados obtenidos demostraron que de los ocho cocos grampositivos aislados, cuatro correspondieron a S. cohnii. Los valores CIM y CBM para S. cohnii productoras y no productoras de biofilm resultaron entre 0,05 y 0,2 g/dL. Mediante la curva de muerte se determino efecto bactericida observando una disminucion de ≥4 log de ufc (1h) tratado con 0,2 y 0,4% de NaClO. La formacion de biofilm para la cepa no tratada fue de DO: 0,12 y para la cepa tratada DO: 0,07 a las 18 h. Aplicar desinfectantes con amplio espectro de accion es importante, debido a que la eliminacion de bacterias puede prevenir su diseminacion y evitar la formacion de biofilms.

Persistence of bacteria in industrial equipment is favoured by biofilm formation. Sodium hypochlorite (NaClO) is routinely used as a disinfectant. The objective of the current study was to determine the inhibitory effect of NaClO on biofilm-producing and non-biofilm-producing S. cohnii strains, isolated from equipment in a fresh pasta factory in Tucuman, Argentina. The following parameters were assayed: production of biofilm, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and NaClO death curves for both biofilm-producing and non-biofilm-producing S. cohnii strains. Four of the eight isolated Gram-positive cocci corresponded to S. cohnii. MIC and MBC values for biofilm-producing and non-biofilm-producing S. cohnii strains were between 0.05 and 0.2 g/dL. A bactericidal effect of 0.2 and 0.4% NaClO for 1 h was established with the death curve, showing a decrease in cfu of ≥4 log units. Biofilm production after 18 h for untreated strains gave an OD of 0.12, whereas the OD of treated strains was 0.07. The use of broad spectrum disinfectants is important, because elimination of bacteria helps prevent their propagation and avoid the formation of biofilms.

A persistência da bactéria em equipamento industrial e resultado do desenvolvimento de biofilmes. O hipoclorito de sodio (NaOCl) e rotineiramente utilizado como desinfetante. O objetivo do trabalho foi determinar o efeito inibitorio do NaClO sobre S. cohnii produtoras e nao produtoras de biofilmes isoladas de uma fabrica de massas frescas a partir de maquinarias de um estabelecimento de Tucuman, Argentina. Foram estudados: producao de biofilme, concentracao inibitoria minima (CIM), concentracao bactericida minima (CBM) e curva de tempo de morte com NaClO perante S. cohnii produtora e naoprodutora de biofilme. Os resultados obtidos demonstraram que quatro dos oito cocos Gram-positivos isolados corresponderam a S. cohnii. Os valores CIM e CBM para S. cohnii produtoras e nao produtoras de biofilme foram entre 0,05 e 0,2 g/dL. Atraves da curva de morte foi determinado um efeito bactericida observando uma diminuicao de ≥ 4 log de ufc (1h) tratado com 0,2 e 0,4% de NaClO. A formacao de biofilme, apos 18 h, para a cepa nao tratada foi de DO: 0,12, ao passo que para a cepa tratada foi de 0,07. A utilizacao de desinfetantes de amplo espectro de acao e importante, visto que a eliminação de bacterias pode prevenir sua propagação e evitar a formacao de biofilmes.

Sanitizer residues in the milk of cows which had passed through footbaths / Resíduos de sanitizantes em vacas de leite após passagem por pedilúvio

Copper sulfate and sodium hypochlorite are used in footbath solutions for the prevention and treatment of bovine digital diseases; however, data on the residues of such elements in milk are sparse in Brazil. This study evaluated the cost of applying the footbath treatment and the total amount of copper and chlorite residues in the milk of healthy cows after they had passed through these footbath solutions. Two groups of 7 cows each (GI and GII) were studied. In the case of GI, 1% sodium hypochlorite was used and for GII 5% copper sulfate was employed in the footbath. The milk samples were collected before the 7-day footbath treatment period (M0) and 24 h (M1), 48 h (M2), 72 h (M3) and 15 days (M15) after the last footbath. Statistical analysis to compare the different samples within each group was carried out by applying Friedman's test, followed by Dunn's test (p<0.05). It was concluded that the amount of total chlorites and copper in the milk of healthy cattle after routine daily footbaths for a period of 7 days presented some variations. However, the concentrations observed were considered insufficient to represent a risk to human health. The cost of the footbath solutions was found to be reasonable.

O sulfato de cobre e o hipoclorito de sódio são empregados na prevenção e tratamento das enfermidades digitais dos bovinos, mas os valores residuais desses elementos foram pouco estudados. Neste estudo, avaliou-se a presença de resíduos de cobre e cloretos totais no leite de vacas saudáveis após passagens dos animais em pedilúvio contendo soluções formuladas com estas substâncias e estimou-se os custos das soluções. Utilizou-se 14 vacas saudáveis distribuídas em dois grupos (GI e GII) de sete animais cada. Em GI, empregou-se solução de hipoclorito de sódio a 1% e, em GII, sulfato de cobre a 5%. As amostras de leite foram colhidas antes da passagem pelo pedilúvio (M0), após 24 (M1), 48 (M2) e 72 (M3) horas, além de 15 dias (M15) subsequentes à última passagem. Na análise estatística, a comparação entre momentos dentro de cada grupo foi realizada com teste de Friedman, seguido pelo teste de Dunn's (p<0,05). Concluiu-se que os valores de cloretos totais e de cobre no leite de bovinos saudáveis, após passagens diárias dos animais em pedilúvio por um período de sete dias, apresentaram algumas variações consideradas insuficientes para provocarem danos à saúde humana e as soluções medicamentosas não apresentaram custos exorbitantes.

Sanitizer residues in the milk of cows which had passed through footbaths / Resíduos de sanitizantes em vacas de leite após passagem por pedilúvio

Copper sulfate and sodium hypochlorite are used in footbath solutions for the prevention and treatment of bovine digital diseases; however, data on the residues of such elements in milk are sparse in Brazil. This study evaluated the cost of applying the footbath treatment and the total amount of copper and chlorite residues in the milk of healthy cows after they had passed through these footbath solutions. Two groups of 7 cows each (GI and GII) were studied. In the case of GI, 1% sodium hypochlorite was used and for GII 5% copper sulfate was employed in the footbath. The milk samples were collected before the 7-day footbath treatment period (M0) and 24 h (M1), 48 h (M2), 72 h (M3) and 15 days (M15) after the last footbath. Statistical analysis to compare the different samples within each group was carried out by applying Friedman's test, followed by Dunn's test (p<0.05). It was concluded that the amount of total chlorites and copper in the milk of healthy cattle after routine daily footbaths for a period of 7 days presented some variations. However, the concentrations observed were considered insufficient to represent a risk to human health. The cost of the footbath solutions was found to be reasonable.(AU)

O sulfato de cobre e o hipoclorito de sódio são empregados na prevenção e tratamento das enfermidades digitais dos bovinos, mas os valores residuais desses elementos foram pouco estudados. Neste estudo, avaliou-se a presença de resíduos de cobre e cloretos totais no leite de vacas saudáveis após passagens dos animais em pedilúvio contendo soluções formuladas com estas substâncias e estimou-se os custos das soluções. Utilizou-se 14 vacas saudáveis distribuídas em dois grupos (GI e GII) de sete animais cada. Em GI, empregou-se solução de hipoclorito de sódio a 1% e, em GII, sulfato de cobre a 5%. As amostras de leite foram colhidas antes da passagem pelo pedilúvio (M0), após 24 (M1), 48 (M2) e 72 (M3) horas, além de 15 dias (M15) subsequentes à última passagem. Na análise estatística, a comparação entre momentos dentro de cada grupo foi realizada com teste de Friedman, seguido pelo teste de Dunn's (p<0,05). Concluiu-se que os valores de cloretos totais e de cobre no leite de bovinos saudáveis, após passagens diárias dos animais em pedilúvio por um período de sete dias, apresentaram algumas variações consideradas insuficientes para provocarem danos à saúde humana e as soluções medicamentosas não apresentaram custos exorbitantes.(AU)

In vitro genotoxicity and cytotoxicity in murine fibroblasts exposed to EDTA, NaOCl, MTAD and citric acid

The aim of the present study was to evaluate the capacity of some root canal irrigants to induce genetic damage and/or cellular death in vitro. Murine fibroblast cells were exposed to ethylenediaminetetraacetic acid (EDTA), sodium hypochlorite (NaOCl), MTAD™ and citric acid in increasing concentrations for 3 h at 37ºC. The negative control group was treated with vehicle control (phosphate buffer solution - PBS) for 3 h at 37°C, and the positive control group was treated with methylmetanesulfonate, 1 μM. for 3 h at 37°C. Cytotoxicity was assessed by the trypan blue test and genotoxicity was evaluated by the single cell gel (comet) assay. The results showed that exposure to 2.5% and 5% NaOCl and 8.5% citric acid resulted in a significant cytotoxic effect. NaOCl, EDTA and citric acid did not produce genotoxic effects with respect to the comet assay data for all evaluated concentrations. Although MTAD was not a cytotoxic agent, it showed significant genotoxic effects at all tested concentrations (ANOVA and Tukey's test; p<0.05). NaOCl, EDTA and citric acid were found to be cytotoxic in a dose-dependent manner, but they were not genotoxic. MTAD did not cause cell death, but presented genotoxic effects.

O objetivo do presente estudo foi avaliar a capacidade de alguns irrigantes endodônticos em induzir danos genéticos e/ou morte celular in vitro. Células de fibroblastos murinos foram expostas ao ácido etilenodiaminotetracético (EDTA), hipoclorito de sódio (NaOCl), MTAD™ e ácido cítrico em concentrações crescentes durante 3 h a 37°C. O grupo controle negativo foi tratado com solução tampão fosfato - PBS por 3 h a 37° C e o grupo controle positivo foi tratado com metilmetanesulfonato a 1 μM por 3 h a 37° C. A citotoxicidade foi testada pelo azul de tripan e a genotoxicidade foi avaliada pelo teste do cometa. Os resultados apontaram que a exposição ao NaOCl a 2,5% e 5%, e ácido cítrico a 21% resultou em efeitos citotóxicos significativos. O NaOCl, EDTA e o ácido cítrico não produziram efeitos genotóxicos no que diz respeito aos dados obtidos pelo ensaio do Cometa em todas as concentrações testadas. Embora o MTAD não tenha sido um agente citotóxico, mostrou efeitos genotóxicos significativos em todas as concentrações testadas (ANOVA e teste de Tuckey; p<0,05). O NaOCl, o EDTA e o ácido cítrico mostraram-se citotóxicos de maneira dose-dependente, mas não genotóxicos. Por outro lado, apesar do MTAD não ter causado a morte celular, foi genotóxico em todas as concentrações testadas.

In vitro genotoxicity and cytotoxicity in murine fibroblasts exposed to EDTA, NaOCl, MTAD and citric acid.

The aim of the present study was to evaluate the capacity of some root canal irrigants to induce genetic damage and/or cellular death in vitro. Murine fibroblast cells were exposed to ethylenediaminetetraacetic acid (EDTA), sodium hypochlorite (NaOCl), MTAD™ and citric acid in increasing concentrations for 3 h at 37ºC. The negative control group was treated with vehicle control (phosphate buffer solution - PBS) for 3 h at 37°C, and the positive control group was treated with methylmetanesulfonate, 1 µM. for 3 h at 37°C. Cytotoxicity was assessed by the trypan blue test and genotoxicity was evaluated by the single cell gel (comet) assay. The results showed that exposure to 2.5% and 5% NaOCl and 8.5% citric acid resulted in a significant cytotoxic effect. NaOCl, EDTA and citric acid did not produce genotoxic effects with respect to the comet assay data for all evaluated concentrations. Although MTAD was not a cytotoxic agent, it showed significant genotoxic effects at all tested concentrations (ANOVA and Tukey's test; p<0.05). NaOCl, EDTA and citric acid were found to be cytotoxic in a dose-dependent manner, but they were not genotoxic. MTAD did not cause cell death, but presented genotoxic effects.

Tissue reaction to silver nanoparticles dispersion as an alternative irrigating solution.

INTRODUCTION: Nanomaterials have been used to create new consumer products as well as applications for life sciences and biotechnology. The aim of this study was to evaluate the tissue response to implanted polyethylene tubes filled with fibrin sponge embedded with silver nanoparticles dispersion. METHODS: Thirty rats received individually 4 polyethylene tubes filled with sponge embedded in 47 ppm, 23 ppm silver nanoparticles dispersion, 2.5% sodium hypochlorite, or with no embedding as control. The observation periods were 7, 15, 30, 60, and 90 days. After each period of time, 6 animals were killed, and the tubes and surrounding tissue were removed, fixed, and prepared to be analyzed in light microscope with glycol methacrylate embedding, 3-µm serial cutting, and hematoxylin-eosin stain. Qualitative and quantitative evaluations of the reactions were performed. RESULTS: Both materials caused moderate reactions at 7 days. The response was similar to the control on the 15th day with 23 ppm silver nanoparticles dispersion and 2.5% sodium hypochlorite and on the 30th day with 47 ppm silver nanoparticles dispersion. CONCLUSIONS: It was possible to conclude that silver nanoparticles dispersion was biocompatible especially in a lower concentration.

Cytotoxicity and genotoxicity of endodontic irrigants on human cells / Citotoxicidade e genotoxicidade de irrigantes endodônticos em células humanas

OBJECTIVE: Endodontic irrigants solutions with antibacterial activity have been used in treatment of teeth with infected root canals; however, these solutions can irritate periapical tissues. The aim of this study was to evaluate the cytotoxity and genotoxicity of different endodontic irrigants solutions – sodium hypochlorite (1% and 2%), calcium hydroxide (0.2%), and HCT20 in human KB cells. MATERIAL AND METHOD: Cells were incubated with solutions for 2 and 24 hours. The cell viability was assessed after the trypan blue exclusion and the frequency of cell death mechanism (apoptotic or necrotic) was determined by acridine orange/ethidium bromide fluorescent dyeing test. The genotoxicity effects were assessed by the micronucleus assays. RESULTS AND DISCUSSION: The results showed that Ca(OH)2 alone or in combination with tergentol (HCT20), and NaOCl induced cytotoxicity in KB causing death cells by apoptosis. The micronuclei test showed that KB treated with NaOCl (1%) present an increase in the frequency of micronucleus compared to the control group.

OBJETIVO: Soluções irrigadoras com atividade antibacteriana têm sido usadas no tratamento de dentes com canais radiculares infectados; entretanto, essas soluções podem irritar os tecidos periapicais. O objetivo deste estudo foi avaliar a citotoxicidade e genotoxicidade de diferentes soluções irrigadoras – hipoclorito de sódio (1% e 2%), hidróxidode cálcio (0,2 %) e HCT em células humanas KB. MATERIAL E MÉTODO: As células foram incubadas em soluções por 2 e 24 horas. A viabilidade celular foi determinada após exclusão do tripan blue e a frequência de mecanismo de morte celular (apoptótica ou necrótica) foi determinada pelo teste acridine Orange/ethidium bromide fluorescen dyeing. Os efeitos de genotoxicidade foram determinados pelo ensaio de micronúcleos. RESULTADOS E DISCUSSÃO: Os resultados demonstraram que o Ca(OH2), isoladamente ou em combinação com Tergentol™ (HCT20) e NaOCl, induziram citotoxicidade em KB, causando morte celular por apoptose. O teste de micronúcleos demonstrou que KB tratado codm NaOCl (1%) apresentou aumento na frequência de microdnúcleos quando comparadocom o grupo controle.

Estado actual del hipoclorito de sodio en endodoncia. 1: propiedades biológicas / Sodium hypochlorite in Endodontics: an update. 1: biologic properties

La solución de hipoclorito de sodio en diferentes concentraciones es uno de los agentes irrigantes más utilizados en endodoncia. El hipoclorito de sodio es un agente antibacteriano efectivo, tiene la capacidad de desintegrar el tejido pulpar vital o necrótico infectado y la propiedad de desnaturalizar las toxinas, actuando además como lubricante durante la preparación del sistema de conductos radiculares. A pesar de la conveniencia de estas características, el hipoclorito de sodio en altas concentraciones se ha manifestado como producto sumamente tóxico tanto in vitro como in vivo. El objetivo de este trabajo fue actualizar la información pertinente a las propiedades biológicas del hipoclorito de sodio utilizado como solución irrigante en endodoncia.

Citotoxidade de diferentes concentrações de hipoclorito de sódio sobre osteoblastos humanos / Citotoxicity of different amounts of sodium hypochlorite on human cultured osteoblasts

Objetivo: Avaliar o efeito citotóxico de diferentes concentrações de hipoclorito de sódio sobre uma cultura de células de osteoblastos humanos (linhagem HOB). Métodos: Culturas confluentes de osteoblastos humanos (linhagem HOB) foram obtidas em meio de Dulbecco modificado, suplementado com 10% de soro fetal bovino e submetidas a incubações com hipoclorito de sódio (concentrações de 0,5; 1,0; 2,5 e 5,25%) durante trinta segundos. O grupo controle foi representado por células incubadas em fosfato de potássio. A avaliação da viabilidade celular foi realizada através do teste de exclusão com azul de Trypan, em triplicata. Durante o período de incubação, imagens foram registradas através de um microscópio óptico invertido, para avaliação da morfologia celular. Resultados: Verificou-se que no grupo controle havia 98,7% de células viáveis, morfologicamente normais, enquanto que nos grupos experimentais, células viáveis não foram observadas. A cinética de citotoxidade seguiu tendência dependente da concentração. Conclusão: O hipoclorito de sódio nas concentrações 0,5; 1,0; 2,5; 5,25%, incubado por trinta segundos em cultura de osteoblastos humanos é citotóxico.

Objective: To evaluate the cytotoxic effect of different amounts of sodium hypochlorite, on a culture of human osteoblastos (HOB) cells. Method: Cultures of human osteoblasts (HOB) in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% of bovine fetal serum were incubated in sodium hypochlorite (concentrations of 0.5; 1.0; 2.5 and 5.25%) for thirty seconds. The control group was represented by cells incubated in phosphate buffered saline (PBS). Cell viability was assessed by means of 0.4% trypan blue dye exclusion test, in triplicate. During the incubation period, images were recorded through an inverted optic microscope to evaluate the cellular morphology. Results: In the control group 98.7% of viable cells were verified, without morphology alterations, while no viable cells were observed in the experimental groups. The kinetics of cytotoxity was concentration-dependent. Conclusion: It was concluded that there was a cytotoxic effect on cultures of human osteoblasts incubated for thirty seconds in sodium hypochlorite in all concentrations (0.5; 1.0; 2.5 and 5.25%).

Super-oxidized solution inhibits IgE-antigen-induced degranulation and cytokine release in mast cells.

Activation of the high affinity IgE receptor (Fc epsilonRI) through IgE-antigen complexes induces mast cell degranulation, synthesis of lipid mediators and cytokine production. These effects are involved in Type I hypersensitivity reactions and controlling them has been the main objective of many anti-allergic therapies. Here we report that pretreatment of murine bone marrow derived mast cells (BMMC) with super-oxidized solution (SOS) inhibits Fc epsilonRI dependent-beta hexosaminidase and cytokine release. This effect is exerted without altering total protein tyrosine phosphorylation, MAPK activation, cytokine mRNA accumulation or calcium mobilization after Fc epsilonRI triggering. Our data suggest that this neutral pH-SOS acts like a mast cell-membrane stabilizer inhibiting the cell machinery for granule secretion without altering the signal transduction pathways induced by IgE-antigen receptor crosslinking.

Behavioral response of zebrafish Danio rerio Hamilton 1822 to sublethal stress by sodium hypochlorite: ecotoxicological assay using an image analysis biomonitoring system.

We evaluated behavioral responses of zebrafish Danio rerio exposed to sublethal concentrations of sodium hypochlorite using an image analysis biomonitoring system (IABS). First, the limits of normal variation in swimming activity of zebrafish were determined by monitoring traveled distance of 40 control fishes using the IABS. An acute toxicity test was performed to determine the LC(50(24 h)) for D. rerio to NaOCl. To evaluate the toxic effects in swimming activity, 32 fishes were exposed to 40%, 30%, 20%, 10% of the LC(50 )and 32 were used as control using the IABS. We considered toxic concentrations where more than 10% intervals of the treated group were below the limits of normal variation and were significantly different from the control group. Two main responses were observed: an escape response (increased swimming activity) at 10% treated group, a gradual decrease in swimming activity from the 20% of the LC(50) on, and an avoidance response at higher concentrations. The response of the 20% treated group were considered as a NOAEL and responses of the 30% and 40% treated groups indicated significant hypoactivity (adverse effect). This behavioral biomonitoring system has proven to be a useful tool to detect sublethal toxicity that could be incorporated in biomonitoring protocols in Brazil.