Aim This study investigated the influence in vitro of different sodium hypochlorite (NaOCl) agitation protocols associated or not with DualRinse (HEDP) on the temperature of the solution. Methods Forty-eight premolars were instrumented and their apical third sealed to allow a closed irrigation system. The teeth remained immersed in a basin of warm water (37°C). The teeth were divided into the groups: G1 ( NaOCl+Passive Ultrasonic Irrigation (PUI)), G2 ( N a O C l / H E D P + P U I), G3 ( NaOCl + EasyClean (EC)) and G4 ( N a O C l / H E D P + E C). The canals were filled with the respective solutions and after 180 seconds the first temperature measurement was taken (T0). Then, the solutions were agitated, following the different protocols, for 60 seconds and a new measurement was performed (T60). The temperature was measured using a digital thermometer for type “K” sensors that was inserted into the middle third of the teeth. At the end of the measurements, the teeth were sectioned and prepared for scanning electron microscopy. The dentinal wall of middle third was graded according to the amount of debris and smear layer remaining on the walls. The results were analyzed using ANOVA test and Tukey’s multiple comparisons (p<0.05). Results G1 and G2 had an average increase in temperature of 1.1°C and 1.65°C, respectively (p>0.05). EasyClean caused a decrease in the temperature of the solutions in both groups, without a significant statistical difference with T0 (p>0.05). Regarding cleaning, it was only possible to observe clean dentinal tubules in the groups with the chelator. PUI discretely increased the temperature of the solution, regardless of the solution. The opposite effect was observed after activation with EasyClean. Conclusion The association of NaOCl with a chelating agent promoted the cleaning of the dentinal tubules.

ABSTRACT: The aim of this in vitro study was to investigate the influence of ethylenediaminetetraacetic acid (EDTA) associated with the benzalkonium chloride (BAK) on the adhesion and formation of Enterococcus faecalis biofilms attached to coated dentin. Discs standard bovine dentin blocks were treated with the coating materials evaluated: Saline solution (control), 17 % EDTA, 17 % EDTA associated with 1 % BAK for 5 minutes and subsequently washed with saline solution. Afterwards, biofilms of E. faecalis (ATCC 29212) were grown on the surface of coated dentin blocks for time intervals of 1 hour and 7 days (n = 20) and were subsequently washed with phosphate-buffered saline (PBS). Bacterial viability and total biovolume were analyzed by confocal laser scanning microscopy (CLSM) using the Live/Dead technique. Nonparametric Kruskal-Wallis followed by Dunn tests were used to determine statistical differences (a = 5 %). The 17 % EDTA + 1 % BAK group showed significantly lower biovolume and bacterial viability values at the end of 1 hour (p < 0.05). After 7 days of contamination, the 17 % EDTA and 17 % EDTA + 1 % BAK groups showed similar results that differed statistically from those of the control group (p < 0.05). The saline solution group showed higher values. The use of BAK associated with EDTA on dentin blocks surfaces before exposure to contamination was able to interfere in the adhesion of E. faecalis to dentin. Also, dentin treatment by BAK associated with a chelating agent influences the secondary biofilm formation, which could have important effects on the long-term success of root canal treatment.

RESUMEN: El objetivo del estudio consistió en investigar in vitro, la influencia del ácido etilendiamino-tetraacético (EDTA) con cloruro de benzalconio (BAK) en la adhesión y formación de biopelículas de Enterococcus faecalis a la dentina. Discos de dentina bovina fueron tratadas con solución salina (control), 17 % de EDTA, 17% de EDTA asociado con 1 % de BAK durante 5 minutos y lavadas con solución salina. Las biopelículas de E. faecalis (ATCC 29212) se cultivaron sobre los discos de dentina durante intervalos de tiempo de 1 hora y 7 días (n = 20), lavados con solución salina tamponada con fosfato (PBS). La viabilidad bacteriana y el biovolumen total se analizaron mediante microscopía de barrido por láser (CLSM) utilizando la técnica Live / Dead. Se realizó prueba no paramétrica de Kruskal-Wallis, seguida por Dunn con una diferencia estadística (a = 5 %). El grupo de 17 % EDTA + 1 % BAK mostró valores significativamente menores de biovolumen y viabilidad bacteriana al final de 1 hora (p < 0,05). Después de 7 días de contaminación, los grupos de 17 % EDTA y 17 % EDTA + 1 % BAK mostraron resultados similares que diferían estadísticamente del grupo control (p < 0,05). La solución salina mostró valores más altos. La asociación de BAK con EDTA antes de la contaminación interfirió en la adhesión de E. faecalis. Además, el tratamiento de la dentina por BAK asociado con EDTA influye en la formación de biopelículas secundarias, lo que podría tener efectos importantes sobre el éxito a largo plazo del tratamiento del conducto radicular.

A determinação da suscetibilidade bacteriana aos medicamentos intracanal é uma necessidade, mas são poucos os estudos que utilizam metodologia própria para anaeróbios estritos nessa avaliação. Neste estudo, são descritos os passos de um método de diluição em caldo, feito em microplacas (microdiluição) e em tubo (macrodiluição), para testar a ação de medicamentos intracanal tradicionais sobre bactérias anaeróbias estritas, com apresentação dos resultados em Concentrações Inibitória e Bactericida Mínimas (CIM e CBM). Inóculos padronizados dos anaeróbios Prevotella nigrescens (ATCC 33563), Fusobacterium nucleatum (ATCC 25586) e Clostridium perfringens (ATCC 13124), em caldo Reinforced Clostridium Medium (RCM) e caldo Brucella suplementado, foram submetidos a diferentes concentrações de soluções de hidróxido de cálcio, digluconato de clorexidina, paramonoclorofenol canforado e formocresol, diluídas nos mesmos caldos de cultura, em microplacas e tubos, e depois incubados em jarras de anaerobiose a 37ºC por 48 h ou 96 h. A determinação das CIMs foi feita através de leituras visual e em espectrofotômetro, e das CBMs, pela semeadura de alíquotas em ágar RCM-sangue. Para esse tipo de estudo, o macrométodo com leitura em espectrofotômetro deve ser a escolha natural. As CIMs e CBMs do macrométodo foram compatíveis com seu conhecido desempenho clínico, variando com as bactérias e meios de cultura empregados. O caldo RCM foi o mais efetivo e o C. perfringens, o microrganismo mais resistente.

The determination of bacterial susceptibility to intracanal medicaments is a necessity. Nevertheless, few studies utilize the proper methodology to carry out that evaluation with anaerobes. In this study, the steps of a broth dilution method, carried out in microplates (microdilution) and tubes (macrodilution), to test the effect of traditional intracanal medicaments on anaerobic bacteria are described. The results are presented as values of minimal inhibitory and bactericidal concentrations (MIC and MBC). Standardized inocula of the anaerobic bacteria Prevotella nigrescens (ATCC 33563), Fusobacterium nucleatum (ATCC 25586) and Clostridium perfringens (ATCC 13124), in reinforced Clostridium medium (RCM) and supplemented Brucella broth, were submitted to different concentrations of calcium hydroxide, chlorhexidine digluconate, camphorated paramonochlorophenol and formocresol solutions. The drugs were diluted in the same culture broths, in microplates and tubes, and were then incubated in anaerobiosis jars at 37ºC for 48 or 96 hours. The determination of MICs was carried out through visual and spectrophotometric readings, and the determination of MBCs, through the plating of aliquots on RCM-blood agar. For that kind of study, the macromethod with spectrophotometric reading should be the natural choice. MICs and MBCs obtained with the macromethod were compatible with the known clinical performance of the studied medications, and the values varied according to the bacteria and culture media employed. RCM was the most effective medium and C. perfringens, the most resistant microorganism.

Foi avaliado in vitro a capacidade antimicrobiana de substâncias utilizadas como agentes antimicrobianos (solução de hidróxido de cálcio 10%, paramonoclorofenol canforado - PMCC, digluconato de clorexidina 2% e detergente de mamona 10%) sobre bactérias anaeróbias (Fusobacterium nucleatum ATCC 25586, Prevotella nigrescens ATCC 33563, Clostridium perfringens ATCC 13124 e Bacteroides fragilis ATCC 25285), utilizando-se a técnica da diluição em caldo. Para a determinação das concentrações inibitória e bactericida mínimas (CIM e CBM), dois caldos, Reinforced Clostridial Medium (RCM) e Brucella suplementado, inóculo padronizado e diluições seriadas foram utilizados. Todos os agentes antimicrobianos apresentaram atividade antimicrobiana, variando para as diferentes espécies bacterianas, não havendo diferença entre os caldos utilizados. O digluconato de clorexidina demonstrou a melhor eficiência, com as menores CIMs, seguido pelo detergente de mamona, PMCC e hidróxido de cálcio. C. perfringens e B. fragilis foram as espécies mais resistentes aos agentes.

The antimicrobial activity of substances used as antibacterial agents (solutions of 10% calcium hydroxide, camphorated paramonochlorophenol - PMCC, 2% chlorhexidine digluconate and 10% castor oil plant detergent) on anaerobic bacteria (Fusobacterium nucleatum ATCC 25586, Prevotella nigrescens ATCC 33563, Clostridium perfringens ATCC 13124 and Bacteroides fragilis ATCC 25285), using a broth dilution technique, was evaluated in vitro. For determination of minimum inhibitory and minimum bactericide concentrations (MIC and MBC), two culture broths, Reinforced Clostridial Medium (RCM) and supplemented Brucella, standardized inoculum and serially diluted solutions were used. All antibacterial agents presented antimicrobial activity that varied for different bacteria. There were no differences in the performance of the two broths. Chlorhexidine digluconate was the most effective, with the lowest MICs, followed by castor oil detergent, PMCC and calcium hydroxide. C. perfringens and B. fragilis were the most resistant bacteria to all agents.