Recomendaciones sobre seguridad química para elementos de limpieza y desinfección, 11 de mayo del 2020 / Recommendations on Chemical Safety for Cleaning and Disinfection Supplies, 11 May 2020 / Recomendações de segurança química para produtos de limpeza e desinfecção, 11 de maio de 2020

En esta ficha se abordan las principales recomendaciones de seguridad frente a la manipulación de agentes desinfectantes, que al ser productos químicos tienen un riesgo y deben manejarse con la debida precaución. Adicionalmente, facilita un resumen con los elementos de aseo que no debemos mezclar y los riesgos que generan.

This technical note addresses the main safety recommendations against the handling of disinfecting agents, which, being chemical products, must be handled with due caution. Additionally, it presents a summary of cleaning elements that should not be mixed and the risks that they generate. Most cleaning products are made from chemicals. • The mix of different chemicals can place people at risk. • Cleaning means removing the dirt. Disinfection means killing microorganisms. Soaps are made to remove dirt, but they can also kill microorganisms, as they break down and destroy the external membranes of the virus. Disinfectants are made to kill microorganisms. • Soaps and bleach are made for different purposes and should not be combined. They should be used separately. • The solutions made by mixing bleach with water need careful measurement. • Bleach is dangerous if used without dilution...

En este informe se presenta un panorama general del impacto que la pandemia de COVID-19 ha tenido en los servicios contra las enfermedades no transmisibles en la Región de las Américas, con datos obtenidos a lo largo de cuatro semanas en mayo del 2020, en un momento en el que se consideraba que la Región era el epicentro de la pandemia mundial de COVID-19.

Tissue dissolution and modifications in dentin composition by different sodium hypochlorite concentrations

ABSTRACT Sodium hypochlorite (NaOCl) remains the most used irrigation solution during root canal preparation because of characteristics such as wide-spectrum antimicrobial activity and organic tissue dissolution capacity. However, these solutions can alter dentin composition and there is no consensus on the optimal concentration of NaOCl to be used. Objectives To determine the organic matter dissolution and changes in dentin chemical composition promoted by different concentrations of NaOCl over time. Material and Methods: Fragments of bovine muscle tissue were weighed before and after 5, 10, and 15 min of immersion in the groups (n=10): G1- 0.9% saline solution; G2- 1% NaOCl; G3- 2.5% NaOCl; and G4- 5% NaOCl. Bovine dentin fragments were subjected to the same irrigants and absorption spectra were collected by Attenuated Total Reflectance of Fourier Transform Infrared Spectroscopy (ATR-FTIR) before and after 0,5, 1, 2, 3, 5, 8, and 10 min of immersion in the solutions. The ratios of the amide III/phosphate and carbonate/phosphate absorption bands were determined. The tissue dissolution and carbonate/phosphate ratios were submitted to the two-way analysis of variance (ANOVA) with Tukey’s multiple-comparison test (α<0.05) and to the one-way analysis of variance with Tukey’s (α<0.05). The amide III/phosphate ratio was analyzed by Friedman test (α<0.05) and the Kruskal-Wallis test with Dunn’s post-hoc (α<0.05). Results The increase in NaOCl concentration and contact time intensified the dissolution of organic matter and dentin collagen with reduction in the amide III/phosphate ratio. Significant differences between all groups (p<0.05) were observed in the dissolution of organic matter at 10 min and in the amide III/phosphate ratio between the saline solution and 5% NaOCl at 5 min. The carbonate/phosphate ratio decreased significantly in G2, G3, and G4 after 0,5 min of immersion (p<0.05), but more alterations did not occur in the subsequent periods (p>0.05). Intergroup differences were not observed in this ratio (p>0.05). Conclusions The increase in the exposure time and in the concentration of NaOCl solution lead to an increase in the tissue dissolution and dentin collagen deproteination. Furthermore, some carbonate ions are removed from the dentin inorganic phase by the NaOCl.

Efecto del ultrasonido endodóntico sobre clorhexidina al 2 por ciento en la formación de paracloroanilina: estudio in vitro / Effect of endodontic ultrasound on 2 percent chlorhexidine in the formation of parachloraniline: in vitro study

Introducción: La clorhexidina (CHX) en solución acuosa se hidroliza generando paracloroanilina (PCA), proceso acelerado por el aumento de temperatura y pH. El uso de ultrasonido endodóntico (USE), basado en fenómenos de oscilación, cavitación, microcorriente acústica, genera calor afectando la CHX. Objetivo Identificar y cuantificar in vitro cambios fisicoquímicos, temperatura y pH, y la cantidad de PCA formada con el uso de ultrasonido endodóntico sobre soluciones de CHX al 2 por ciento. Materiales y métodos La CHX 2 por ciento se activó durante 30, 60, 90 y 120 seg con USE a 24.500 Hz, midiendo antes y después de activación: pH, temperatura y cantidad de PCA, leyendo a 375 nm en curva de calibración de estándares de PCA y formación, registrando el espectro de absorción mediante espectrofotómetro UV-visible. Resultados El USE aumentó la temperatura en 1 °C independiente del tiempo de aplicación y acidificó la solución de CHX 2 por ciento, sin variaciones significativas en pH y temperatura. No se observó coloración ni formación de precipitado en muestras activadas por USE a los diferentes tiempos. Las muestras no presentaron valores medibles de PCA a 375 nm. Los espectros de absorción de CHX 2 por ciento y activadas por USE por más de 60 seg presentaron curvas espectrales, peaks y valores de absorbancia diferentes. Conclusiones El USE aumenta la temperatura y acidifica la solución de la CHX en todos los tiempos de aplicación. No se detectó presencia de PCA por espectrofotometría visible. Muestras activadas por USE por 60 seg o más presentan espectros de absorción diferentes a las muestras sin activar. Diferencias en los espectros de absorción entre CHX activadas con USE y con CHX sin activar indicarían degradación de la CHX y posible presencia de PCA.

Introduction: Chlorhexidine (CHX) in aqueous solution is hydrolysed to p-chloroaniline (PCA), a process accelerated by increasing temperature and pH. Using endodontic ultrasound based on oscillation phenomena, cavitation, and acoustic microstreaming generates heat, affecting the CHX. Objective The aim of this in vitro study was to identify and quantify the physical-chemical changes, temperature and pH, and the amount of PCA formed by increasing the temperature of 2 percent CHX by endodontic ultrasound. Materials and methods Samples of 2 percent CHX were activated for 30, 60, 90, and 120 seconds with endodontic ultrasound 24,500 Hz. The pH and temperature were measured before and after activation, as well as the formation and amount of PCA, by reading and recording the result obtained from a standard calibration curve reading at 375 nm in a UV-visible light spectrophotometer. Results Independent of time, ultrasound increased the temperature of 2 percent CHX by 1 °C and acidified the solution. No significant changes were recorded in pH and temperature. No staining or precipitates were observed in samples ultrasonically activated at different times. Samples read at 375 nm showed no measurable PCA values. Absorption spectra of 2 percent CHX and 2 percent CHX activated for more than 60 seconds showed different spectral curves, peaks, and absorbance values. Conclusions Ultrasound increased the temperature and acidified the solution of CHX for all application times. No PCA was detected by visible spectrophotometry. Absorption spectra of 2 percent CHX activated with ultrasound at different times differs from 2 percent CHX without activation. These differences indicate degradation of CHX and possible presence of PCA.

Stability of antimicrobial activity of peracetic acid solutions used in the final disinfection process

The instruments and materials used in health establishments are frequently exposed to microorganism contamination, and chemical products are used before sterilization to reduce occupational infection. We evaluated the antimicrobial effectiveness, physical stability, and corrosiveness of two commercial formulations of peracetic acid on experimentally contaminated specimens. Stainless steel specimens were contaminated with Staphylococcus aureus, Escherichia coli, Candida albicans, blood, and saliva and then immersed in a ready peracetic acid solution: 2% Sekusept Aktiv (SA) or 0.25% Proxitane Alpha (PA), for different times. Then, washes of these instruments were plated in culture medium and colony-forming units counted. This procedure was repeated six times per day over 24 non-consecutive days. The corrosion capacity was assessed with the mass loss test, and the concentration of peracetic acid and pH of the solutions were measured with indicator tapes. Both SA and PA significantly eliminated microorganisms; however, the SA solution was stable for only 4 days, whereas PA remained stable throughout the experiment. The concentration of peracetic acid in the SA solutions decreased over time until the chemical was undetectable, although the pH remained at 5. The PA solution had a concentration of 500-400 mg/L and a pH of 2-3. Neither formulation induced corrosion and both reduced the number of microorganisms (p = 0.0001). However, the differences observed in the performance of each product highlight the necessity of establishing a protocol for optimizing the use of each one.

A microleakage study of gutta-percha/AH Plus and Resilon/Real self-etch systems after different irrigation protocols

The development and maintenance of the sealing of the root canal system is the key to the success of root canal treatment. The resin-based adhesive material has the potential to reduce the microleakage of the root canal because of its adhesive properties and penetration into dentinal walls. Moreover, the irrigation protocols may have an influence on the adhesiveness of resin-based sealers to root dentin. Objective: The objective of the present study was to evaluate the effect of different irrigant protocols on coronal bacterial microleakage of gutta-percha/AH Plus and Resilon/Real Seal Self-etch systems. Material and Methods: One hundred ninety pre-molars were used. The teeth were divided into 18 experimental groups according to the irrigation protocols and filling materials used. The protocols used were: distilled water; sodium hypochlorite (NaOCl)+eDTA; NaOCl+H3PO4; NaOCl+eDTA+chlorhexidine (CHX); NaOCl+H3PO4+CHX; CHX+eDTA; CHX+ H3PO4; CHX+eDTA+CHX and CHX+H3PO4+CHX. Gutta-percha/AH Plus or Resilon/Real Seal Se were used as root-filling materials. The coronal microleakage was evaluated for 90 days against Enterococcus faecalis. Data were statistically analyzed using Kaplan-Meier survival test, Kruskal-Wallis and Mann-Whitney tests. Results: No significant difference was verified in the groups using chlorhexidine or sodium hypochlorite during the chemo-mechanical preparation followed by eDTA or phosphoric acid for smear layer removal. The same results were found for filling materials. However, the statistical analyses revealed that a final flush with 2% chlorhexidine reduced significantly the coronal microleakage. Conclusion: A final flush with 2% chlorhexidine after smear layer removal reduces coronal microleakage of teeth filled with gutta-percha/AH Plus or Resilon/Real Seal SE. .

Efeito das nanopartículas de quitosana e da variação da concentração, temperatura e pH do hipoclorito de sódio sobre biofilmes orais formados in situ / Effect of chitosan nanoparticles and the temperature and pH variations of sodium hypochlorite on biofilms formed in situ

O objetivo deste estudo foi avaliar se a variação da temperatura e pH do hipoclorito de sódio (NaOCl), incrementa sua capacidade antibacteriana e de dissolução. Foi avaliado também, se as nanopartículas de Quitosana (CNPs) inibem o crescimento bacteriano e removem a lama dentinária. Foram utilizados 260 blocos de dentina bovina infetados intra-oralmente. As soluções experimentais foram NaOCl a 1% e 2.5%, a temperatura ambiente e 37oC e acidificado a pH 5 e 7. Os tempos de exposição foram 5 e 20 min. Os espécimes foram analisados pré (controle) e pósirrigação. Após esta análise, as amostras foram incubadas em BHI por 24 horas e analisadas novamente quanto a reativação bacteriana. Estes procedimentos foram realizados em duplicado para poder determinar a porcentagem de limpeza dentinária. Para analisar o efeito quelante das CNPs sobre a dentina infetada in situ, as amostras receberam uma irrigação final com CNPs em solução e analisadas imediatamente ou infetadas intra-oralmente para avaliar o efeito antibacteriano. O NaOCl apresentou poder antibacteriano e foi capaz de dissolver significativamente o biofilme sem importar sua temperatura. O NaOCl em pHs ácidos apresentaram alto poder antibacteriano, contudo seu poder de dissolução decresceu. As CNPs foram capazes de significativamente remover a lama dentinária e interferir com o crescimento bacteriano sobre dentina. Portanto, a temperatura do NaOCl não é relevante quando é testada sobre biofilmes multi-espécies. O poder antibacteriano do NaOCl foi inversamente proporcional a seu pH, enquanto que a sua capacidade de dissolução foi diretamente proporcional. As CNPs podem ser uma alternativa para o uso de EDTA devido a suas propriedades quelantes e de interferir com a adesão inicial das bactérias sobre dentina.

The aim of this study was to evaluate if the variation of the sodium hypochlorite (NaOCl) temperature and pH increase its antibacterial and dissolution abilities. It was also evaluated if the chitosan nanoparticles (CNPs) inhibit the bacterial growth and remove smear layer. Two hundred-sixty bovine dentin blocks were infected intraorally. The experimental solutions were 1% and 2.5% NaOCl at room temperature and 37oC. the solution was acidified at pH 5 and 7. The exposure times were 5 and 20 min. The specimens were analyzed pre- (control) and postirrigation. After that, the samples were incubated in BHI and analyzed again to evaluate the bacterial recolonization. These procedures were performed in duplicate to access the percentage of dentinal cleaning. The samples were rinsed with a final irrigation of CNPs and analyzed immediately to determine the chelating effect, or infected intraorally to evaluate its antibacterial ability. NaOCl showed antibacterial power and was able to significantly dissolve the biofilm regardless its temperature. NaOCl at acid pHs showed great antibacterial properties, however its dissolution ability decreased. The CNPs were able to remove significantly the smear layer and interfere with the bacterial growth on dentin. Therefore, the NaOCl temperature is not relevant when the solution was tested on multi-specie biofilms. The antibacterial power of NaOCl was inversely proportional to its pH, while its dissolution capacity was directly proportional. CNPs could be an alternative instead of EDTA due to its chelating properties and ability to interfere with the earlier bacterial adhesion on dentin.

Efeito das nanopartículas de quitosana e da variação da concentração, temperatura e pH do hipoclorito de sódio sobre biofilmes orais formados in situ / Effect of chitosan nanoparticles and the temperature and pH variations of sodium hypochlorite on biofilms formed in situ

O objetivo deste estudo foi avaliar se a variação da temperatura e pH do hipoclorito de sódio (NaOCl), incrementa sua capacidade antibacteriana e de dissolução. Foi avaliado também, se as nanopartículas de Quitosana (CNPs) inibem o crescimento bacteriano e removem a lama dentinária. Foram utilizados 260 blocos de dentina bovina infetados intra-oralmente. As soluções experimentais foram NaOCl a 1% e 2.5%, a temperatura ambiente e 37oC e acidificado a pH 5 e 7. Os tempos de exposição foram 5 e 20 min. Os espécimes foram analisados pré (controle) e pósirrigação. Após esta análise, as amostras foram incubadas em BHI por 24 horas e analisadas novamente quanto a reativação bacteriana. Estes procedimentos foram realizados em duplicado para poder determinar a porcentagem de limpeza dentinária. Para analisar o efeito quelante das CNPs sobre a dentina infetada in situ, as amostras receberam uma irrigação final com CNPs em solução e analisadas imediatamente ou infetadas intra-oralmente para avaliar o efeito antibacteriano. O NaOCl apresentou poder antibacteriano e foi capaz de dissolver significativamente o biofilme sem importar sua temperatura. O NaOCl em pHs ácidos apresentaram alto poder antibacteriano, contudo seu poder de dissolução decresceu. As CNPs foram capazes de significativamente remover a lama dentinária e interferir com o crescimento bacteriano sobre dentina. Portanto, a temperatura do NaOCl não é relevante quando é testada sobre biofilmes multi-espécies. O poder antibacteriano do NaOCl foi inversamente proporcional a seu pH, enquanto que a sua capacidade de dissolução foi diretamente proporcional. As CNPs podem ser uma alternativa para o uso de EDTA devido a suas propriedades quelantes e de interferir com a adesão inicial das bactérias sobre dentina...

The aim of this study was to evaluate if the variation of the sodium hypochlorite (NaOCl) temperature and pH increase its antibacterial and dissolution abilities. It was also evaluated if the chitosan nanoparticles (CNPs) inhibit the bacterial growth and remove smear layer. Two hundred-sixty bovine dentin blocks were infected intraorally. The experimental solutions were 1% and 2.5% NaOCl at room temperature and 37oC. the solution was acidified at pH 5 and 7. The exposure times were 5 and 20 min. The specimens were analyzed pre- (control) and postirrigation. After that, the samples were incubated in BHI and analyzed again to evaluate the bacterial recolonization. These procedures were performed in duplicate to access the percentage of dentinal cleaning. The samples were rinsed with a final irrigation of CNPs and analyzed immediately to determine the chelating effect, or infected intraorally to evaluate its antibacterial ability. NaOCl showed antibacterial power and was able to significantly dissolve the biofilm regardless its temperature. NaOCl at acid pHs showed great antibacterial properties, however its dissolution ability decreased. The CNPs were able to remove significantly the smear layer and interfere with the bacterial growth on dentin. Therefore, the NaOCl temperature is not relevant when the solution was tested on multi-specie biofilms. The antibacterial power of NaOCl was inversely proportional to its pH, while its dissolution capacity was directly proportional. CNPs could be an alternative instead of EDTA due to its chelating properties and ability to interfere with the earlier bacterial adhesion on dentin...

Experimental evaluation of cyclic fatigue resistance of four different nickel-titanium instruments after immersion in sodium hypochlorite and/or sterilization

NiTi instruments have a high risk of separation due to torsional or flexural fatigue (cyclic fatigue). Chemomechanical preparation, cleaning procedures, chemical disinfection and sterilization cause the corrosion of endodontic instruments that may weaken the fracture resistance of the instruments. Objective To assess the effects of NaOCl immersion and autoclave sterilization on the cyclic fatigue resistance of ProFile, FlexMaster, Mtwo and TwistedFiles NiTi instruments (tip size 25, 0.06 taper, n=160). Material and Methods The instruments (n=10 for each subgroup) were dynamically immersed in NaOCl; immersed in NaOCl and sterilized in one autoclave cycle; 5 cycles immersed in NaOCl and sterilized in autoclave and not immersed in NaOCl and not sterilized (control group). Dynamic cyclic fatigue resistance was tested. The number of cycles to failure (NCF) were statistically analyzed (P<0.05). Results Kruskall-Wallis test indicated significant differences among the tested instruments in terms of NCF (P=0.000). The mean NCF of Mtwo (556.75) was higher than that of the Twisted File, Flexmaster and ProFile, 483.1, 376.12, 365.25, respectively. NaOCl immersion and autoclave sterilization have no effect on the NCF values of the tested instruments (P>.05). Conclusions Cyclic fatigue resistance of the tested NiTi instruments cannot be adversely affected by NaOCl immersion and autoclave sterilization. Production process (TwistedFiles) or design (Twisted Files, FlexMaster, Mtwo and ProFile) of the instruments can influence their cyclic fatigue resistance. .

Effects of reprocessing on chemical and morphological properties of guide wires used in angioplasty / Efeitos do reprocessamento nas propriedades químicas e morfológicas de fios-guia usados em angioplastia

OBJECTIVE: To investigate the influence of the reprocessing technique of enzymatic bath with ultrasonic cleaning and ethylene oxide sterilization on the chemical properties and morphological structure of polymeric coatings of guide wire for regular guiding catheter. METHODS: These techniques simulated the routine of guide wire reprocessing in many hemodynamic services in Brazil and other countries. Samples from three different manufacturers were verified by scanning electron microscopy and X-ray photoelectron spectroscopy. RESULTS: A single or double sterilization of the catheters with ethylene oxide was not associated with morphological or chemical changes. However, scanning electron microscopy images showed that the washing method was associated with rough morphological changes, including superficial holes and bubbles, in addition to chemical changes of external atomic layers of polymeric coating surfaces, as detected by the X-ray photoelectron spectroscopy method, which is compatible with extended chemical changes on catheter surfaces. CONCLUSION: The reprocessing of the catheters with ethylene oxide was not associated with morphological or chemical changes, and it seemed appropriate to maintain guide wire coating integrity. However, the method combining chemical cleaning with mechanical vibration resulted in rough anatomical and chemical surface deterioration, suggesting that this reprocessing method should be discouraged.

OBJETIVO: Investigar a influência das técnicas de reprocessamento de banho enzimático com limpeza ultrassônica e a esterilização com óxido de etileno nas propriedades químicas e estruturas morfológicas de revestimentos poliméricos de fios-guia usados como guias em cateteres regulares. MÉTODOS: Estas técnicas simulam a rotina de processamento de fios-guia em muitos serviços de hemodinâmica do Brasil e de outros países. Amostras de três diferentes fabricantes foram verificadas por microscopia eletrônica de varredura e espectroscopia de fotoelétrons de raios-X. RESULTADOS: Uma única ou dupla esterilização dos cateteres com óxido de etileno não foi associada a mudanças químicas ou morfológicas. Contudo, imagens de microscopia eletrônica de varredura mostraram que o método de lavagem foi associado a intensas modificações morfológicas, incluindo bolhas e buracos superficiais, assim como mudanças nas ligações químicas das camadas atômicas externas do revestimento polimérico, conforme demonstrado por resultados de espectroscopia de fotoelétrons de raios-X, compatível com extensas modificações químicas induzidas por esse processo de lavagem. CONCLUSÃO: O reprocessamento dos fios-guia de cateteres com óxido de etileno não está associado a mudanças químicas e morfológicas dos mesmos e pode ser considerado adequado para manter a integridade destes materiais. Entretanto, o método que combina lavagem química com vibração mecânica resulta em intensas deteriorações anatômicas e químicas, sugerindo que esse método de processamento deve ser desencorajado.

Effect of different disinfecting procedures on the hardness and color stability of two maxillofacial elastomers over time

Objective Disinfection procedures often cause deterioration in a maxillofacial prosthesis. Color and hardness alterations could lead to a replacement of the prosthesis. Material and Methods An experimental chlorinated polyethylene (CPE) and a commercial polydimethyl siloxane (PDMS) sample were treated with four different disinfection procedures for a period which simulates 1 year of clinical service. The applied disinfection procedures included microwave exposure and immersion in three solutions, sodium hypochlorite, neutral soap and a commercial disinfecting soap. Shore A hardness (∆H) and color differences (∆E) were determined before and after each procedure. All data were analyzed by Two Way Analysis of Variance (ANOVA) and Tukey's post hoc tests at a level of α=0.05. Results The samples presented significant alterations in color and hardness after the different disinfection treatments. The color differences (∆E) were at least eye detectable in all cases and clinically unacceptable in most of the cases, with values ranging from 1.51 to 4.15 and from 1.54 to 5.92 for the PDMS and CPE material, respectively. Hardness was decreased after all the disinfection procedures in the PDMS, while for the CPE, a decrement was observed after disinfection with sodium hypochlorite and neutral soap and an increment after microwave exposure and the disinfection with a commercial antimicrobial agent. The PDMS samples presented greater alterations in color and hardness after disinfection with sodium hypochlorite solution, while the microwave exposure caused negligible effects. The CPE samples were affected most after disinfection when treated with neutral soap, and more slightly when disinfected with sodium hypochlorite solution. Conclusions The disinfection procedures caused alterations in color and hardness of the examined materials. The most suitable disinfection procedure for ...

Influence of disinfectant solutions on test materials used for the determination of masticatory performance

Masticatory function can be evaluated objectively as the capacity of an individual to fragment solid food after a fixed number of chewing cycles, the so-called masticatory performance (MP). The objective of this study was to evaluate the reliability of four different test materials (Optosil, Optocal, Zetapuls, and Perfil) and five disinfection protocols by aspersion and immersion (no disinfection, 2% glutaraldehyde, 2% chlorhexidine, 5.25% sodium hypochlorite, and 70% alcohol) on the MP, determined at three moments (24 hours, 15 and 60 days) after storing the fragmented blocks. MP was evaluated by calculating X50 through the sieving technique and the Rosim-Ramler equation. The weight and microbiologic count (colony forming units, CFUs) of chewed blocks were measured to identify any variations that would make MP determination unfeasible. Differences in MP were observed among the materials (p < 0.01). Perfil presented the highest X50 value (worst MP determination), followed by Zetaplus (both p < 0.05), Optosil, and Optocal (both p > 0.05). The time and disinfection type had no influence on MP (p > 0.05). The number of CFUs differed between the nondisinfected group and all other disinfection groups at all time points (p < 0.01). No other significant difference in CFU count between disinfection groups was observed. In conclusion, disinfection did not alter the reliability of the test materials for the MP calculation for up to 60 days.

Influência da solução de clorexidina a 2% na resistência adesiva de pinos de fibra de vidro em raízes bovinas: acompanhamento imediato, 6 meses e 1 ano / 2% chlorhexidine influence on fiber posts bond strength to bovine roots: immediate, 6-month and 1-year-aging

Este trabalho teve como objetivo avaliar a influência da solução de clorexidina a 2% na resistência adesiva de pinos de fibra de vidro cimentados com cimento resinoso convencional utilizando três diferentes sistemas adesivos (2 convencionais e 1 autocondicionante), no período de 7 dias, 6 meses e 1 ano. Foram selecionadas 180 raízes bovinas, que foram tratadas endodonticamente e divididas em 6 grupos (n=30): MP, sistema adesivo (SA) convencional de 3 passos (ScotchBond Multi Uso); SB, SA convencional de 2 passos (Single Bond); SE, SA autocondicionante de 2 passos (Clearfil SE Bond); MP-CHX, SB-CHX e SE-CHX, com aplicação da clorexidina (CHX). Em todos os grupos, o pino de fibra de vidro Exacto foi cimentado com cimento resinoso dual RelyX ARC. Cada grupo foi dividido em 3, de acordo com o período experimental, 7 dias, 6 meses e 1 ano (n=10). Após a obtenção de fatias com 1mm de espessura, os espécimes foram submetidos ao teste de push-out (100kg, 0,5mm/min). Os tipos de falhas foram analisados em microscópio ótico de luz (40x) e classificados em: adesiva cimento/dentina; adesiva cimento/pino; coesiva em dentina ou cimento, e mista. Os valores, convertidos em MPa, foram analisados pelo teste ANOVA a 4 critérios e teste de Tukey para comparação das médias, com nível de significância de 5%. Não houve diferença estatística com o uso da CHX para os SAs convencionais testados, nos períodos de 7 dias, 6 meses e 1 ano (p>0,05). Dentre os SA, o MP foi o que se manteve constante com ou sem CHX (p>0,05). Houve diminuição de resistência adesiva no terço cervical, em 1 ano, e no terço apical em 7 dias do SE-CHX (p<0,05). Pode-se concluir que o uso da CHX pareceu não interferir na resistência adesiva dos SAs testados, exceto para o SA autocondicionante, em 7 dias e 1 ano.

The aim of this work was to evaluate the 2% chlorhexidine influence on fiber posts bond strength luted with a resin cement, with three different dentin bonding systems (2 etch-and-rinse and 1 self-etching), with 7-day, 6-month and one-year-aging. One hundred and eighty bovine roots were endodontically treated and randomly assigned to 6 groups (n=30): MP, three-step etch-and-rinse dentin bonding system (DBS) (ScotchBond Multi Uso); SB, two-step etch-and-rinse DBS (Single Bond); SE, twostep self-etching DBS (Clearfil SE Bond); MP-CHX, SB-CHX and SE-CHX, with chlorhexidine (CHX) application. Exacto fiber posts were luted with dual cure resin cement RelyX ARC in all groups. Each group was divided in three, according to aging (n=10). After obtainning 1mm-thick slices, push-out test was carried out (100kg, 0,5mm/min). Failure modes were assessed under light microscopy (40x) and classified in: adhesive to dentin; adhesive to post; cohesive in dentin or cement, and mixed failure. Values were converted to MPa and analyzed by 4-way ANOVA and Tukeys test for multiple comparisons, at 5% significance level. There was no difference with the use of CHX for tested etch-and-rinse DBSs, after 7-day, 6-month and one-year-aging (p>0,05). Among DBSs, MP presented constant values (p>0,05). SE-CHX presented significant lower bond strength values on the cervical third, at one year, and apical third at 7 days (p<0,05). It can be concluded that CHX use seemed not to interfere bond strength values of all materials tested, except for the self-etch DBS, after 7 days and one year-aging.

Influência da solução de clorexidina a 2% na resistência adesiva de pinos de fibra de vidro em raízes bovinas: acompanhamento imediato, 6 meses e 1 ano / 2% chlorhexidine influence on fiber posts bond strength to bovine roots: immediate, 6-month and 1-year-aging

Este trabalho teve como objetivo avaliar a influência da solução de clorexidina a 2% na resistência adesiva de pinos de fibra de vidro cimentados com cimento resinoso convencional utilizando três diferentes sistemas adesivos (2 convencionais e 1 autocondicionante), no período de 7 dias, 6 meses e 1 ano. Foram selecionadas 180 raízes bovinas, que foram tratadas endodonticamente e divididas em 6 grupos (n=30): MP, sistema adesivo (SA) convencional de 3 passos (ScotchBond Multi Uso); SB, SA convencional de 2 passos (Single Bond); SE, SA autocondicionante de 2 passos (Clearfil SE Bond); MP-CHX, SB-CHX e SE-CHX, com aplicação da clorexidina (CHX). Em todos os grupos, o pino de fibra de vidro Exacto foi cimentado com cimento resinoso dual RelyX ARC. Cada grupo foi dividido em 3, de acordo com o período experimental, 7 dias, 6 meses e 1 ano (n=10). Após a obtenção de fatias com 1mm de espessura, os espécimes foram submetidos ao teste de push-out (100kg, 0,5mm/min). Os tipos de falhas foram analisados em microscópio ótico de luz (40x) e classificados em: adesiva cimento/dentina; adesiva cimento/pino; coesiva em dentina ou cimento, e mista. Os valores, convertidos em MPa, foram analisados pelo teste ANOVA a 4 critérios e teste de Tukey para comparação das médias, com nível de significância de 5%. Não houve diferença estatística com o uso da CHX para os SAs convencionais testados, nos períodos de 7 dias, 6 meses e 1 ano (p>0,05). Dentre os SA, o MP foi o que se manteve constante com ou sem CHX (p>0,05). Houve diminuição de resistência adesiva no terço cervical, em 1 ano, e no terço apical em 7 dias do SE-CHX (p<0,05). Pode-se concluir que o uso da CHX pareceu não interferir na resistência adesiva dos SAs testados, exceto para o SA autocondicionante, em 7 dias e 1 ano.

The aim of this work was to evaluate the 2% chlorhexidine influence on fiber posts bond strength luted with a resin cement, with three different dentin bonding systems (2 etch-and-rinse and 1 self-etching), with 7-day, 6-month and one-year-aging. One hundred and eighty bovine roots were endodontically treated and randomly assigned to 6 groups (n=30): MP, three-step etch-and-rinse dentin bonding system (DBS) (ScotchBond Multi Uso); SB, two-step etch-and-rinse DBS (Single Bond); SE, twostep self-etching DBS (Clearfil SE Bond); MP-CHX, SB-CHX and SE-CHX, with chlorhexidine (CHX) application. Exacto fiber posts were luted with dual cure resin cement RelyX ARC in all groups. Each group was divided in three, according to aging (n=10). After obtainning 1mm-thick slices, push-out test was carried out (100kg, 0,5mm/min). Failure modes were assessed under light microscopy (40x) and classified in: adhesive to dentin; adhesive to post; cohesive in dentin or cement, and mixed failure. Values were converted to MPa and analyzed by 4-way ANOVA and Tukeys test for multiple comparisons, at 5% significance level. There was no difference with the use of CHX for tested etch-and-rinse DBSs, after 7-day, 6-month and one-year-aging (p>0,05). Among DBSs, MP presented constant values (p>0,05). SE-CHX presented significant lower bond strength values on the cervical third, at one year, and apical third at 7 days (p<0,05). It can be concluded that CHX use seemed not to interfere bond strength values of all materials tested, except for the self-etch DBS, after 7 days and one year-aging.

Effect of repeated immersion solution cycles on the color stability of denture tooth acrylic resins

OBJECTIVE: Chemical solutions have been widely used for disinfection of dentures, but their effect on color stability of denture tooth acrylic resins after repeated procedures is still unclear. The aim of this in vitro study was to evaluate whether repeated cycles of chemical disinfectants affected the color stability of two denture tooth acrylic resins. MATERIAL AND METHODS: Sixty disc-shaped specimens (40 mm x 3 mm) were fabricated from two different brands (Artiplus and Trilux) of denture tooth acrylic resin. The specimens from each brand (n=30) were randomly divided into 6 groups (n=5) and immersed in the following solutions: distilled water (control group) and 5 disinfecting solutions (1 percent sodium hypochlorite, 2 percent sodium hypochlorite, 5.25 percent sodium hypochlorite, 2 percent glutaraldehyde, and 4 percent chlorhexidine gluconate). Tooth color measurements were made by spectrophotometry. Before disinfection, the initial color of each tooth was recorded. Further color measurements were determined after subjecting the specimens to 7, 21, 30, 45, 60, and 90 immersion cycles in each tested solution. Color differences (ΔE*) were determined using the CIE L*a*b* color system. Data were analyzed using two-way repeated measures analysis of variance (ANOVA) followed by Tukey tests. The significance level was set at 5 percent. RESULTS: There were statistically significant differences in ΔE* among the 5 disinfectants and water during the 90 cycles of immersion for both denture tooth acrylic resins. Distilled water promoted the greatest color change in both denture tooth acrylic resins, nevertheless none of tested disinfectants promoted ΔE* values higher than 1.0 on these acrylic materials during the 90 cycles of disinfection. CONCLUSIONS: Repeated immersion cycles in disinfecting solutions alter ΔE* values, however these values do not compromise the color of the tested denture tooth acrylic resins because they are imperceptible to the human eye.

Changes in roughness of denture base and reline materials by chemical disinfection or microwave irradiation: Surface roughness of denture base and reline materials

OBJECTIVE: The effect of disinfection by immersion in sodium perborate solution and microwave irradiation on surface roughness of one denture base resin (Lucitone 550 -L), 3 hard chairside reline resins (Tokuyama Rebase II-TR, New Truliner-NT, Ufi Gel hard-UH) and 3 resilient reline materials (Trusoft-T; Sofreliner-S, Dentusil-D) was evaluated. MATERIAL AND METHODS: Thirty specimens of each material were made and divided into 3 groups: Control - not disinfected; P - daily disinfection by immersing in sodium perborate solution (3.8 percent); MW - microwave disinfection (6 min/650 W). Roughness measurements were made after polymerization (baseline) and after 1, 3 and 28 days. Roughness differences relative to the baseline readings were analyzed by Student's t-test (P=0.05). RESULTS: At baseline, Trusoft showed the highest (P<0.001) mean surface roughness (3.54 µm), and its surface roughness was significantly reduced after 28 days of disinfection by immersion in sodium perborate (P=0.013). Roughness measurements of material Trusoft were not performed after microwave disinfection due to the severe alterations on the surface. In the 3 groups evaluated, changes in roughness were significant for materials Ufi Gel hard (from 0.11 to 0.26 µm; P<0.041) and New Truliner (0.19 to 0.76 µm; P<0.019). The roughness of materials Lucitone 550 (0.37 µm), Tokuyama Rebase II (0.37 µm), Sofreliner (0.49 µm) and Dentusil (0.38 µm) remained unaffected (P>0.05). CONCLUSIONS: The roughness of the hard reline materials Ufi Gel hard and New Truliner was adversely affected by microwave disinfection, immersion in water or in sodium perborate. Microwave disinfection caused severe alterations on the surface of the resilient liner Trusoft.

Dissolution of bovine pulp tissue in solutions consisting of varying NaOCl concentrations and combined with EDTA

This in vitro study evaluated (1) the dissolution of bovine pulp tissue in solutions consisting of varying NaOCl concentrations and combined with EDTA; and (2) the pH of these solutions before and after the experiment. The independent variables were the concentration and the volume of the solution. Thirty bovine pulps were divided in equal fragments, resulting in 90 fragments of pulp tissue. Each fragment was immersed in one of the following solutions: 1 percent NaOCl (4 ml), 2.5 percent NaOCl (4 ml), 1 percent NaOCl + 17 percent EDTA (2 ml : 2 ml), 1 percent NaOCl + 17 percent EDTA (1 ml : 3 ml), 2.5 percent NaOCl + 17 percent EDTA (2 ml : 2 ml), and 2.5 percent NaOCl + 17 percent EDTA (1 ml : 3 ml). The test solutions were dichotomized as either able or not able to dissolve the tissue, the latter being attributed when the dissolution of the pulp tissue was not complete within 48 hours. When the samples were able to dissolve the tissue, the time required for complete tissue dissolution was submitted to statistical analysis. The pH of the solutions was measured before and after the experiment. The pH variable was dichotomized as either changed or unchanged. The results demonstrated that the NaOCl solutions combined with 17 percent EDTA were not able to dissolve the tissue. The t-test revealed that the 2.5 percent NaOCl solution presented a lower mean dissolution time than the 1 percent NaOCl solution (p < 0.001). The pH of the solutions with equal volumes of NaOCl and EDTA decreased in 48 hours.

Controle de soluções sanificantes por meio do potencial de óxido-redução em alface americana minimamente processada / Sanitizers' control by means of oxidation-reduction potential on minimally processed Iceberg Lettuce

A presença no mercado brasileiro de hortifrutícolas minimamente processadas atende a uma demanda por produtos prontos para consumo, decorrente das alterações econômicas e socioculturais ocorridas na população. As avaliações microbiológicas desses produtos têm revelado inadequação aos padrões da legislação sanitária. O reaproveitamento das soluções sanificantes é uma prática comum e a eficácia desses métodos necessita ser avaliada. Neste trabalho, objetivou-se quantificar o material oxidável desprendido em imersões sucessivas de alface americana por meio de demanda química de oxigênio (DQO) e verificar sua interferência na ação de sanificantes comerciais. Foram testadas as soluções de hipoclorito de sódio (Virex Plus FLV 2 por cento), dióxido de cloro estabilizado (Tecsaclor) e dicloro-S-triazinatriona sódica diidratada (Sumaveg) preparadas segundo a orientação do fabricante, nos tempos de contato de 2, 5, 10 e 15 min contra E. coli ATCC 11229. O comportamento de reação química de contato dos sanificantes, da matéria orgânica e do inóculo foi medido por meio do potencial de óxido-redução (POR) e contagem dos microrganismos viáveis após os tempos de contato. As soluções de dióxido de cloro e dicloro-S-triazinatriona apresentam mais de 5 reduções logarítmicas na população inicial. A solução de hipoclorito de sódio apresentou variabilidade na eficácia na presença de matéria orgânica, tanto na solução preparada no momento do uso como solução "envelhecida". Discute-se também a viabilidade do uso de um medidor portátil de POR como um instrumento de campo para controle de desinfecção de hortifritícolas.

Effect of microwave disinfection on denture base adaptation and resin surface roughness

This study evaluated the effect of disinfection methods [chemical disinfection (immersion in 100 ppm chloride solution) or microwave disinfection (690 W for 6 min)] on the internal adaptation of denture bases and resin surface roughness. For the adaptation test, 18 maxillary denture bases were obtained from stone casts duplicated from a metallic master model and submitted to the following treatments: 1) control (no disinfection), 2) chemical disinfection or 3) microwave disinfection. Disinfection procedures were performed twice (T1, T2) with a 7-day interval between them. Internal adaptation was measured at baseline (T0) and after T1 and T2 by weighing a vinyl polysiloxane film reproducing the gap between the resin base and the master model. For surface roughness measurement, 60 rectangular (5x10x40 mm) resin specimens were either mechanically or chemically polished and then submitted to the disinfection treatments. Surface roughness (Ra) was recorded after polishing (T0) and after T1 and T2. Data were analyzed by ANOVA GLM for repeated measures and Bonferroni correction at 5 percent significance level. Bases submitted to microwave disinfection had gradual increase of misfit, while bases immersed in chloride solution did not differ from the control group. Surface roughness increased in the mechanical polishing groups with microwave disinfection and decreased in the chemical polishing groups.

Este estudo avaliou o efeito de métodos de desinfecção [desinfecção química (imersão em solução clorada 100 ppm) ou desinfecção por microondas (690 W por 6 min)] na adaptação interna de bases de próteses totais e na rugosidade superficial da resina. Para o teste de adaptação, 18 bases superiores foram duplicadas a partir de um modelo-mestre metálico e submetidas aos seguintes tratamentos: 1) controle (sem desinfecção), 2) desinfecção química ou 3) desinfecção por microondas. Os procedimentos de desinfecção foram realizados duas vezes (T1, T2) com intervalo de 7 dias. A adaptação interna foi medida no baseline (T0), após T1 e T2 por pesagem de um filme de silicona de adição que reproduzia o espaço entre base de resina e modelo-mestre. Para a rugosidade superficial, 60 espécimes retangulares (5x10x40 mm) receberam polimento mecânico ou químico e foram submetidos aos tratamentos de desinfecção. A rugosidade superficial (Ra) foi registrada após o polimento (T0) e após T1 e T2. Os dados foram analisados por ANOVA GLM para medições repetidas e teste de Bonferroni com nível de significância de 5 por cento. As bases submetidas à desinfecção por microondas tiveram aumento gradual de desadaptação, enquanto que as bases imersas em solução clorada não diferiram do grupo controle. A rugosidade superficial aumentou nos grupos de polimento mecânico e desinfecção por microondas e diminuiu nos grupos de polimento químico.

Microbiologically influenced corrosion in petroleum product pipelines--a review.

Microbiologically influenced corrosion is responsible for most of the internal corrosion problems in oil transportation pipelines and storage tanks. One problematic area in treating gas lines is the occurrence of the stratification of water in the line. Under these conditions, corrosion inhibitors do not come into contact properly and oil and inhibitors undergo degradation. The role of bacteria on oil degradation, the consequences of oil degradation in fuel systems and its influence on corrosion have been explained in detail. Besides, factors influencing on degradation of oil and corrosion inhibitors have also been discussed. Mechanism of microbiologically influenced corrosion in oil pipeline has been explained. Many of the misapplication of biocides/inhibitors occur mainly because the characteristics of biocides/inhibitors are not considered before use in pipeline industry. List of biocides and monitoring programme have been collected from literature and presented.