RESUMEN La cavidad oral alberga una gran cantidad de microorganismos que son potenciales patógenos, como el Citomegalovirus, Virus de la Hepatitis B (VHB), Virus de la Hepatitis C, Virus del Herpes simple tipos 1 y 2, Virus de la Inmunodeficiencia Humana, Mycobacterium tuberculosis y actualmente con la aparición del SARS COV-2 causante del covid-19, la comunidad odontológica debe tomar medidas más estrictas en sus protocolos de protección contra enfermedades. Para evaluar su eficacia germicida se aplicó la luz ultravioleta con distintos tiempos de exposición sobre las impresiones dentales de alginato, inmediatamente después de haber tomado la impresión, que al entrar en contacto con la cavidad oral del paciente está contaminada.Obteniendo como resultado una disminución en tamaño y cantidad de las colonias bacterianas en la mayoría de las muestras en las que se aplicó la luz UV LED a los 10 y 15 minutos de exposición.. Lo anterior, confirma su capacidad germicida gracias a su espectro ultravioleta de 245 nm que afecta la cadena de ADN y ARN de los microorganismos ya que es la longitud de onda de máxima absorción de su molécula, eliminando su capacidad reproductiva y de supervivencia. Las ventajas que ofrece como: su pequeño tamaño, fácil de manipular e instalar, que no requiere de un constante mantenimiento, bajo costo de adquisición; su luz de alta intensidad constante que no genera ningún aumento en la temperatura,lo hacen un excelente auxiliar desinfectante que puede incorporarse a las clínicas dentales.

ABSTRACT The oral cavity houses a large number of microorganisms that are potential pathogens, such as cytomegalovirus, hepatitis B virus (HBV), hepatitis C virus, herpes simplex virus types 1 and 2, human immunodeficiency virus, mycobacterium tuberculosis and currently with the appearance of the SARS COV-2 that causes covid-19, the dental community must take stricter measures in its protection protocols against diseases. To evaluate its germicidal efficacy, ultraviolet light was applied with different exposure times on the alginate dental impressions, immediately after having taken the impression, which when it came into contact with the oral cavity of the patient is contaminated. As a result, a decrease in size and quantity of the bacterial colonies was observed in most of the samples in which the UV LED light was applied at 10 and 15 minutes of exposure. Some samples showed less bacterial growth even after 5 minutes of exposure. All this confirms its germicidal capacity thanks to its 245 nm ultraviolet spectrum that affects the DNA and RNA chain of microorganisms since it is the wavelength of maximum absorption of its molecule, eliminating its reproductive and survival capacity. The advantages it offers such as its small size, easy to handle and install, that it does not require constant maintenance, low acquisition cost; its constant high intensity light that does not generate any increase in temperature, makes it an excellent disinfectant auxiliary that can be incorporated into dental clinics.

Abstract Salmonella enterica serovar Heidelberg (SH), often isolated from broiler chicken samples, damages the entire production chain due to its high resistance in the environment. The search for sustainable disinfectant agents has intensified, focusing on the action of essential oils. This work's objective was to evaluate the in vitro, effect of Thymus vulgaris essential oil (TEO) and thymol in SH isolated from broilers, and the cytotoxicity in animal cells. Four different concentrations of TEO (0.1%, 0.2%, 0.4%, and 0.8%, (v/v)) were used against five SH isolates obtained from broilers and ATCC 8326. Thymol was evaluated at the concentrations of 0.023%, 0.047%, 0.071%, and 0.094% (v/v). In vitro antibacterial assays were performed by quantifying viable planktonic cells in the broth microdilution test. The MTT technique was used to assess the cytotoxicity in IEC-6 intestinal cells and NCTC fibroblasts. IC50 was assessed testing the concentrations of 0.0625%, 0.125%, 0.25%, and 0.5% of TEO and thymol in 24 hours. The bacterial activity was observed from the 0.2% concentration of TEO since no colony-forming units were observed. Thymol in the concentration of 0.094% controlled 83.33% of the bacteria. TEO presented an IC50 of 0.14% and 1.22%, while the IC50 for thymol was 0.068% and 0.001% for the IEC-6 and NCTC cells, respectively. On the other hand, TEO showed low cytotoxicity in fibroblasts and a potential action capacity to eliminate SH strains in vitro. SH, , (SH) samples environment intensified oils works work s (TEO 0.1%, 01 0 1 (0.1% 02 2 04 4 0.4% 08 8 0.8% v/v vv v (v/v) 8326 0023 023 0.023% 0047 047 0.047% 0071 071 0.071% 0094 094 0.094 v/v. . test IEC6 IEC 6 IEC- IC IC5 00625 0625 0.0625% 0125 125 0.125% 025 25 0.25% 05 5 0.5 hours 0.2 colonyforming colony forming 8333 83 33 83.33 bacteria 014 14 0.14 122 22 1.22% 0068 068 0.068 0001 001 0.001 respectively hand (SH 0.1% (0.1 0.4 0.8 (v/v 832 002 0.023 004 0.047 007 07 0.071 009 09 0.09 0062 062 0.0625 012 12 0.125 0.25 0. 833 3 83.3 0.1 1.22 006 06 0.06 000 00 0.00 (0. 0.02 0.04 0.07 0.0 0.062 0.12 83. 1.2 (0 1. (

ABSTRACT: The goal of endodontics is to prevent or cure apical periodontitis. Therefore, microorganisms that have colonized the root canal system must be eliminated to promote regeneration and healing. Unfortunately, the existence of accessory canals, anastomoses, isthmus, as well as apical ramifications, form a complex three-dimensional network inside the root, which makes difficult the total elimination of bacteria and detritus. Conventional endodontic therapy has several limitations. Endodontic instruments have been shown to leave 35 % or more of the dentin surface untreated. On the other hand, the inability of generating a turbulent flow, prevents the irrigant from reaching areas that are difficult to access. This facilitates the persistence of bacterial biofilms and the survival of a significant number of viable bacteria. Laser-activated Irrigation (LAI) has been proposed as a co-adjuvant to chemo-mechanical therapy to improve cleaning and disinfection. Er, Cr: YSGG (2780nm) and Er: YAG (2940nm) lasers are the most widely used. These two wavelengths are capable of being widely absorbed by different irrigating solutions, taking into account safe use and respecting accepted clinical parameters.The deep absorption of laser energy generates steam bubbles inside the fluid, which release shear forces when imploding. This phenomenon, called cavitation, is responsible for greater cleaning and disinfection within the root canal system, even in areas difficult to access. Several studies have demonstrated the antibacterial effectiveness of LAI through microbiological methods and microscopic techniques. Recently, it has been reported that LAI would have the ability to increase the antibacterial capacity of low concentration of sodium hypochlorite (a good disinfectant but extremely toxic), which would allow working with concentrations that are safer for the patient.

RESUMEN: El objetivo de la endodoncia es prevenir o curar la periodontitis apical. Por lo tanto, los microorganismos que han colonizado el sistema de canales radiculares deben ser eliminados para promover la regeneración y cicatrización. Desafortunadamente, la existencia de canales accesorios, anastomosis, istmos, así como ramificaciones apicales, genera una compleja red tridimensional en el interior de la raíz, lo que dificulta la eliminación total de bacterias y detritus. La te rapia endodóntica convencional utilizada actualmente presenta una serie de limitaciones.Se ha demostrado que los instrumentos endodónticos dejan un 35 % o más de superficie dentinaria sin tratar. Por otro lado, la imposibilidad de generar un flujo turbulento en el interior de los canales, impide que el irrigante llegue a zonas de difícil acceso. Esto facilita la persistenc ia de biopelículas bacterianas y la supervivencia de un número importante de bacterias viables. La irrigación activada por láser (LAI) ha sido propuesta como una tecnología co-adyuvante a la terapia quimio-mecánica para optimizarla limpieza y desinfección. Los láseresde Er,Cr:YSGG (2780nm) y Er:YAG (2940nm) son los más utilizados. Estas dos longitudes de onda son capaces de ser absorbidas ampliamente por diferentes soluciones irrigantes, teniendo en cuenta un uso seguro y respetando los parámetros clínicos aceptados. La absorción de la energía del láser por parte de los irrigantes, genera burbujas de vapor en el interior del fluido, que liberan fuerzas de cizalla al implosionar. Este fenómeno, denominado cavitación, genera mayor limpieza y desinfección del interior del sistema de canales radiculares, incluso en zonas de difícil acceso. Diversos estudios microbiológicos y microscópicos, han demostrado la efectividad antibacteriana de LAI. Recientemente, se ha publicado que LAI tendría la capacidad de incrementarla capacidad antibacteriana del hipoclorito de sodio a baja concentración (un buen desinfectante pero extraordinariamente tóxico), lo que permitiría trabajar con concentraciones menores y por lo tanto más seguras para el paciente.

Abstract Understanding the behavior of Candida spp. when exposed to denture disinfectants is essential to optimize their effectiveness. Changes in the virulence factors may cause increased resistance of Candida spp. to disinfectant agents. Objective To evaluate the microbial load, cellular metabolism, hydrolytic enzyme production, hyphae formation, live cell and biofilm quantification of Candida albicans, Candida tropicalis and Candida glabrata after exposure to disinfectant solutions. Methodology Simple biofilms were grown on heat-polymerized acrylic resin specimens, and divided into groups according to solutions/strains: distilled water (control); 0.25% sodium hypochlorite (NaOCl 0.25% ); 10% Ricinus communis (RC 10%); and 0.5% Chloramine T (CT 0.5%). The virulence factors were evaluated using the CFU count (microbial load), XTT method (cell metabolism), epifluorescence microscopy (biofilm removal and live or dead cells adhered), protease and phospholipase production and hyphae formation. Data were analyzed (α=0.05) by one-way ANOVA/ Tukey post hoc test, Kruskal-Wallis test and Wilcoxon test. Results NaOCl 0.25% was the most effective solution. CT 0.5% reduced the number of CFUs more than RC 10% and the control. RC 10% was effective only against C. glabrata. RC 10% and CT 0.5% decreased the cellular metabolism of C. albicans and C. glabrata. Enzyme production was not affected. Hyphal growth in the RC 10% and CT 0.5% groups was similar to that of the control. CT 0.5% was better than RC 10% against C. albicans and C. tropicalis when measuring the total amount of biofilm and number of living cells. For C. glabrata, CT 0.5% was equal to RC 10% in the maintenance of living cells; RC 10% was superior for biofilm removal. Conclusions The CT 0.5% achieved better results than those of Ricinus communis at 10%, favoring the creation of specific products for dentures. Adjustments in the formulations of RC 10% are necessary due to efficacy against C. glabrata. The NaOCl 0.25% is the most effective and could be suitable for use as a positive control.

Abstract Although infections with NonTuberculous Mycobacteria have become less common in AIDS patients, they are important opportunistic infections after surgical procedures, likely because they are ubiquitous and not efficiently killed by many commonly used disinfectants. In Venezuela there have recently been many non-tuberculous mycobacteria soft tissue infections after minor surgical procedures, some apparently related to the use of a commercial disinfectant based on a Quaternary Ammonium Compound. We studied the activity of this and other quaternary ammonium compounds on different non-tuberculous mycobacteria by transforming the mycobacteria with a dnaA-gfp fusion and then monitoring fluorescence to gauge the capacity of different quaternary ammonium compounds to inhibit bacterial growth. The minimum inhibitory concentration varied for the different quaternary ammonium compounds, but M. chelonae and M. abscessus were consistently more resistant than M. smegmatis, and M. terrae more resistant than M. bovis BCG.

Resumen Aspidosperma polyneuron es un especie nativa de la región neotropical, en países como Colombia, Venezuela, Perú, Brasil, Argentina y Paraguay, propio de bosques semideciduos, catalogada desde 1998 por la UICN como "En Peligro (EN)", debido a que sus poblaciones naturales fueron sometidas a una intensa explotación con fines madereros y su hábitat se vio seriamente degradado por actividades agrícolas y silvopastoriles. Las dificultades para su regeneración natural y el enraizamiento de las estacas, hace que el cultivo in vitro sea una eficaz herramienta para contrarrestar las dificultades reproductivas que presenta. Sin embargo, la presencia de contaminantes que afectan la viabilidad de los explantes, precisa el desarrollo de protocolos que permitan el establecimiento in vitro de la especie. El objetivo de la presente investigación fue lograr el establecimiento aséptico y la inducción de la callogénesis en explantes de A. polyneuron, mediante la evaluación de diferentes tratamientos de desinfección. Los explantes se obtuvieron de individuos de regeneración natural, en el municipio de Armero, departamento del Tolima, los cuales se sumergieron en agua destilada con una gota de Tween® 80 por cada 100 ml, durante 10 minutos y lavados con agua destilada estéril. Se utilizaron como agentes desinfectantes, el hipoclorito de sodio y el dicloruro de mercurio a distintas concentraciones y tiempos de inmersión. De los explantes utilizados: ápices, segmentos nodales y láminas foliares, este último fue seleccionado por su capacidad de producir callos friables de color verde, para lo cual una desinfección con dicloruro de mercurio (HgCl2) al 0.125% durante 10 minutos fue suficiente para el control de la contaminación y bajos índices de oxidación.

Abstract Aspidosperma polyneuron is a species native to the Neotropics, in countries like Colombia, Venezuela, Peru, Brazil, Argentina and Paraguay, typical of semi-deciduous forests, catalogued since 1998 by the IUCN as "Endangered (EN)", because its natural populations were subjected to an intense exploitation for timber and its habitat was seriously degraded by agricultural and silvopastoral activities. The difficulties for its natural regeneration and the rooting of cuttings, make the in vitro culture an efficient tool to counteract the reproductive difficulties that it presents. However, the presence of pollutants that affect the viability of the explants needs the development of protocols that allow the in vitro establishment of this species. The objective of this research was to achieve aseptic establishment and the induction of callogenesis in explants of A. polyneuron, by evaluating different disinfection treatments. The expants were obtained from individuals of natural regeneration, in the Municipality of Armero in the Department of Tolima, which were immersed in distilled water with a drop of Tween® 80 for each 100 ml, for 10 minutes and then rinsed with sterile distilled water. There were used as disinfectant agents, sodium hypochlorite and mercury dichloride in different concentrations and times of immersion. Among the used explants: buds, nodal segments and leaf blades, the last one was selected for its capacity of producing friable and green callosity, for which a disinfection with mercury dichloride (HgCl2) 0.125% for 10 minutes was enough for contamination control and low indexes of oxidation.

Objective: to evaluate the effectiveness of disinfectant LopHene ST by contact plates method. Methods: one ml of the suspension of reference microorganisms (bacteria, yeast and a filamentous fungus) was taken and spread over a surface made of a material similar to that in which the disinfectant was applied. At random positions and in three replications, the surface was sampled by the contact plates method containing Tryptone Soy Agar and Sabouraud Dextrose Agar plus neutralizing substance. Microorganisms were incubated at 32 ± 2 ºC for 3 to 5 days and at 22 ± 2 ºC for 5 to 7 days, depending on the type of microorganism to be tested. Colony-forming unit on the plates (positive control) were counted, then the prepared disinfectant (4 % concentration) was used over an equal sized area during 10 minutes. The procedure was exactly the same as in the positive control; a reduction of the number of microorganisms by at least 3 logarithms, was adopted as acceptance criteria. Results: the disinfectant reduced the bacterial concentration in a range from 4.60 to 7.20 logarithms for the three tested batches. In the case of yeast, reduction was 4.70 to 5.40 logarithms and for the filamentous fungus, the reduction ranged from 4.10 to 5.50 logarithms. Conclusions: LopHene ST disinfectant is effective for the tested microorganism strains in the evaluated time lapse and at the tested concentration. This confirms the bactericidal and fungicidal capacity of this product under the studied conditions. It was also shown that the method is valid for the analysis of effectiveness of the evaluated disinfectant batches since the colonies were reduced.

Objetivo: evaluar la efectividad del desinfectante LopHene ST mediante el método de placas de contacto. Métodos: se tomó 1 mL de la suspensión de los microorganismos de referencia (bacterias, levadura y un hongo filamentoso) y se esparció sobre una superficie de material análogo al material donde se aplica el desinfectante. En posiciones aleatorias en réplicas de tres, se realizó el muestreo de superficie con placas de contacto que contenían agar triptona soya y sabouraud dextrosa agar, más neutralizante. Se incubaron a 32 ± 2 ºC de 3 a 5 días y 22 ± 2 ºC de 5 a 7 días, según tipo de microorganismo a ensayar. Se contaron las unidades formadoras de colonias en las placas (control positivo). Sobre una superficie de igual dimensión, se aplicó el desinfectante preparado (concentración: 4 %) con 10 min de exposición. Se procedió de igual manera que con el control positivo, se tomó como criterio de aceptación una reducción del número de microorganismos en al menos 3 logaritmos. Resultados: los tres lotes evaluados mostraron que el desinfectante redujo la concentración de las bacterias en un rango de 4,60 a 7,20 logaritmos. Para la levadura la reducción fue de 4,70 a 5,40 logaritmos y para el hongo filamentoso ensayado los valores estuvieron entre 4,10 y 5,50 logaritmos. Conclusiones: el desinfectante LopHene ST es eficaz frente a las cepas de microorganismos ensayadas en el tiempo evaluado y a la concentración probada; con esto se confirma su capacidad bactericida y fungicida bajo las condiciones estudiadas. Además se demuestra que el método empleado resulta válido para el análisis de la efectividad de los lotes de desinfectante evaluados, al mostrar la reducción de las colonias.

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.

A characteristic from Salmonella is its capacity to form biofilms. These structures can become sources of contamination in the production of safe food, as they resist treatment with antibiotics and are difficult to remove in normal cleaning procedures. Therefore the objectives of this study were: 1) determine the capacity of Salmonella strains isolated from prickly pear (10 strains), water samples (2 strains) and soil (3 strains) to form biofilms and 2) evaluate the bactericidal effect of disinfectants citric acid, lactic acid and sodium hypochlorite on biofilm-forming strains. We used the method of O'Toole and Kolter (1998) and polystyrene plates (Coster®) with minimal essential medium with glucose (MEM) and determined the optical density (OD) to estimate the production of biofilms. The disinfectants were applied to plates with biofilm formation in simple MEM 48 h at 37 °C. All strains showed biofilm production after 24 h although there were significant differences (Tukey α= 0.05), depending on the incubation time with respect to the values of OD. The soil strains expressed it's the capacity faster than water and prickly pear. Sodium hypochlorite (200 ppm) and lactic acid (1.5 x 10-4) inhibited cell growth when applied for 20 min on biofilms. The results obtained demonstrate the importance of implementing good agricultural practices in the production of prickly pear as a strategy to prevent contamination by Salmonella strains biofilms forming in vivo, where the effect of treatment with sanitizers may vary.

Una característica de Salmonella es su capacidad para formar biopelículas. Estas estructuras pueden convertirse en focos de contaminación en la producción de alimentos inocuos, ya que resisten tratamientos con antimicrobianos y son difíciles de remover en procedimientos normales de limpieza. Por lo anterior los objetivos del presente estudio fueron: 1) determinar la capacidad de cepas de Salmonella, aisladas de nopal verdura (10 cepas), muestras de agua (2 cepas) y suelo (3 cepas), para formar biopelículas y 2) evaluar el efecto bactericida de los desinfectantes ácido cítrico, ácido láctico e hipoclorito de sodio sobre cepas formadoras de biopelículas. Se utilizó el método de OToole y Kolter (1998) y placas de poliestireno (Coster®) con medio esencial mínimo con glucosa (MEM) y se determinó la densidad óptica (D.O) para estimar la producción de biopelículas. Los desinfectantes se aplicaron a placas con formación de biopelículas en MEM simple de 48 h a 37 °C. Todas las cepas registraron producción de biopelículas desde las 24 h aunque se obtuvieron diferencias significativas (Tukey α= 0.05), dependiendo del tiempo de incubación con respecto a los valores de D. O. Las cepas de suelo expresaron su capacidad más rápidamente que las de agua y nopal. El hipoclorito de sodio (200 ppm) y el ácido láctico (1.5 X 10-4) inhibieron el crecimiento de células cuando se aplicaron por 20 min sobre las biopelículas. Los resultados aquí obtenidos evidencian la importancia de implementar las buenas prácticas agrícolas en la producción de nopal, como estrategia para prevenir la contaminación por cepas de Salmonella formadoras de biopelículas in vivo, donde el efecto de los tratamientos con sanitizantes pudiera variar.

Este estudo avaliou a atividade antibacteriana do extrato de Rosmarinus officinalis e do potencial deste extrato vegetal para a desinfecção de cones de guta-percha (GP). No primeiro experimento, o extrato hidroalcoólico de Rosmarinus officinalis (folhas), em diluição de 10% m/v, foi testado contra Enterococcus faecalis, utilizando o método de discodifusão em ágar. Os controles positivos e negativos foram o álcool de cereais 70% e antibióticos, respectivamente. Os procedimentos foram realizados em triplicata e os diâmetros de halos de inibição foram mensurados com um paquímetro, após 24 horas a 37 º C. No segundo experimento, os procedimentos de desinfecção foram avaliados em cones de GP artificialmente contaminados com Enterococcus faecalis. O extrato de R. officinalis foi comparado com o gluconato de clorexidina a 2% e com hipoclorito de sódio a 2,5% através de um teste de exposição direta por 5 minutos. Cones esterili - zados e cones não desinfectados foram utilizados como controles negativo e positivo, respectivamente. Após 24h de incubação, as contagens bacterianas foram enumeradas. Em ambos os experimentos, os dados foram analisados estatisticamente pelos testes de Kruskall-Wallis e Tukey (p <0,05). O extrato vegetal apresentou halos de inibição semelhantes aos antibióticos testados. Expessiva descontaminação dos cones foi verificada com todas as soluções desinfetantes, sem dife - renças significativas entre elas. O extrato de R. officinalis mostrou efeito bactericida sobre Enterococcus faecalis e capacidade de desinfetar cones de GP contaminados com este microrganismo.

This study evaluated the antibacterial activity of Rosmarinus officinalis extract and its potential for disinfecting guttapercha (GP) cones. In the first experiment, a hydro-alcoholic extract of Rosmarinus officinalis (leaves) in a dilution ratio of 10% m/v was tested against Enterococcus faecalis by using the disk diffusion method. Positive and negative controls were 70% cereal alcohol and antibiotics, respectively. The procedures were performed in triplicate, and the diameters of the zones of growth inhibition were measured with a caliper after 24 h at 37ºC. In the second experiment, the disinfection procedures were evaluated on GP cones artificially contaminated with Enterococcus faecalis. The R. officinalis extract was compared with 2% chlorhexidine digluconate and 2.5% sodium hypochlorite, using a direct exposure test (5 min treatment). Sterilized and non-disinfected cones were used as negative and positive controls, respectively. After 24 h of incubation, bacterial counts were taken. For both experiments, the data were statistically analyzed by Kruskall-Wallis and Tukey's tests (p<0.05). The plant extract produced zones of inhibition comparable to those of tested antibiotics. Significant GP cone disinfection was verified with all disinfectant solutions, with no significant difference between them. R. officinalis extract showed bactericidal effect on Enterococcus faecalis and capacity to disinfect GP cones contamined with it.

Este estudo propôs avaliar, através da microscopia eletrônica de varredura (MEV), a capacidade de limpeza e remoção de "smear layer" e debris das paredes de canais radiculares preparados e irrigados com soluções de hipoclorito de sódio (NaOCl) a 2,5%, gluconato de clorexidina (CLX) a 2,0% e soro fisiológico (controle). Utilizaram-se 50 dentes unirradiculares extraídos com um único canal. Cortaram-se as coroas no limite cervical e os canais foram preparados até o instrumento 45. Durante o preparo foram feitas irrigações com as soluções a serem avaliadas: Grupo 1: NaOCl a 2,5% (10 raízes); Grupo 2: NaOCl a 2,5% seguido de irrigação com EDTA a 17% por 2 minutos (10 raízes); Grupo 3: CLX a 2,0% (10 raízes); Grupo 4: CLX a 2,0% e EDTA a 17% por 2 minutos (10 raízes); Grupo 5: soro fisiológico (5 raízes); Grupo 6: soro fisiológico e EDTA a 17% por 2 minutos (5 raízes). Após o preparo, os canais foram irrigados com as soluções em teste, e as raízes cortadas no sentido V-L para avaliação por MEV, nos terços cervical, médio e apical, verificando-se a presença de "smear layer" e debris. Os dados relativos aos escores atribuídos foram avaliados pelo teste Kruskal-Wallis com p = 5%. Os resultados mostraram que o uso do EDTA diminuiu significativamente (p < 0,05) a "smear layer" para todas as soluções avaliadas em todos os terços. Quando não se utilizou o EDTA, somente para o grupo do NaOCl, verificou-se quantidade significativamente maior de "smear layer" no terço apical. Exceto para a CLX, o uso de EDTA diminuiu significativamente a quantidade de debris. Concluiu-se, que após o preparo, faz-se necessária a utilização do EDTA a fim de promover melhor limpeza das paredes dos canais radiculares.

The purpose of this study was to carry out a scanning electron microscopic (SEM) analysis of the cleaning qualities and smear layer removal from root canal walls, instrumented and irrigated with 2.5% NaOCl, 2.0% chlorhexidine and saline solutions. Fifty extracted teeth were used in this study. All teeth were radiographed to determine the existence of a single canal. The crowns were cut at the cervical limit and the root canals were instrumented with K-type files up to size 45. During root canal preparation, irrigations were made with the different solutions being evaluated: Group 1: 2.5% NaOCl (10 roots); Group 2: 2.5% NaOCl and 17% EDTA for 2 minute (10 roots); Group 3: 2.0% chlorhexidine (10 roots); Group 4: 2.0% chlorhexidine and 17% EDTA for 2 minutes (10 roots); Group 5: saline solution (5 roots); Group 6: saline solution and 17% EDTA for 2 minutes (5 roots). After instrumentation, the canals were irrigated with each one of the solutions and the roots were cut in the buccolingual direction for SEM analysis, at the cervical, middle and apical thirds, to ascertain the presence or absence of smear layer and debris. SEM analysis was performed by three calibrated examiners and scores were submitted to Kruskal-Wallis test at the significance level of p = 5%. Results showed that the use of 17% EDTA decreased the smear layer significantly (p < 0.05) for all evaluated solutions in all thirds. When EDTA was not used, a significantly higher quantity of smear layer on the apical third was observed only in the NaOCl groups. The use of 17% EDTA was significant for debris removal except for the chlorhexidine groups. The following conclusion could be drawn: the use of 17% EDTA was necessary to enhance cleanness of the root canals.