ABSTRACT Introduction: The effect of oxygen on the surface of resins at the moment of photopolymerization creates a layer which is susceptible to pigments. The use of glycerin may block this effect. Objective: Determine whether there is a difference in the color stability of nanohybrid composite resin subjected to a coloring agent when glycerin is either applied or not applied. Methods: Sixty resin disks were distributed into Group 1 (without glycerin) and Group 2 (with glycerin). Photopolymerization was performed for 20 s with a Bluephase®N LED lamp. The first color measurement was taken with an Easyshase®V spectrophotometer, recording the values obtained for L* (luminosity), a* (red-green axis) and b* (blue-yellow axis). The second color measurement was taken after immersion of the samples for one month in Coca-Cola®, maintaining them in an incubator at 37ºC. Statistical data analysis was performed with Student's t test to determine the color stability changes occurring in the two groups and compare them. Results: Color stability changes were observed in all the resin samples. Mean distance between initial and final color was ΔE = 6.91 in Group 1 and ΔE = 3.74 in Group 2. A statistically significant difference was found between the two groups analyzed (p < 0.001). Conclusions: Glycerin is an effective substance to block the effect of oxygen on the resin surface, preventing the formation of an oxygen-inhibited layer and raising the color stability of the nanohybrid composite resin.

RESUMEN Introducción: El efecto del oxígeno sobre la superficie de las resinas al momento de la fotopolimerización origina una capa que es susceptible a los pigmentos. El uso de la glicerina puede bloquear este efecto. Objetivo: Determinar si existe diferencia en la estabilidad del color de la resina compuesta nano-híbrida sometida a un agente colorante, al aplicar o no la glicerina. Métodos: 60 discos de resina se dividieron en Grupo 1 (sin glicerina) y Grupo 2 (con glicerina). La fotopolimerización se realizó por 20 s con la lámpara LED Bluephase®N. Se realizó la primera medición del color con el espectrofotómetro Easyshase®V y se registraron los valores arrojados para L* (luminosidad), a* (eje rojo-verde) y b* (eje azul-amarillo). Posterior a la inmersión por 1 mes de las muestras en Coca-Cola®, manteniéndolas en una incubadora a 37 ºC, se realizó la segunda medición del color. Se procesaron los datos estadísticamente con la prueba t de Student para determinar las variaciones en la estabilidad del color de ambos grupos y compararlos entre sí. Resultados: En todos los especímenes del experimento existió alteración en la estabilidad del color de la resina. La media de la distancia entre el color inicial y el color final del Grupo 1 fue de ΔE = 6,91, mientras en el Grupo 2 fue ΔE = 3,74. Se halló diferencia estadísticamente significativa entre ambos grupos analizados (p < 0,001). Conclusiones: La glicerina es una sustancia efectiva para bloquear el efecto del oxígeno en la superficie de la resina y evitar la formación de la capa inhibida de oxígeno, aumentando la estabilidad del color de la resina compuesta nano-híbrida.

Introduction: as part of endodontic treatment, root canals are cleaned and shaped, since shavings of dentin and organic materials, such as microorganisms, resulting from the action of instrumentation, create the so-called dental smear. Objective: carry out an in vitro evaluation of smear layer removal and dentinal tubule density reduction using chelating irrigation solutions. Methods: an experimental study was conducted for which 30 single-rooted human teeth were selected after initial radiographic examination to verify the presence of a single canal, absence of calcification, internal resorption and endodontic treatment either completed or underway. Next, instrumentation was performed with three different irrigation solutions: 17 % ethylenediaminetetraacetic acid, 10% citric acid and 5.25% sodium hypochlorite (control group). Each instrumented tooth was then evaluated radiographically using a density scale made of aluminum with different density markers. Scanning electron microscope analysis was performed on three teeth from each group, which were treated with different irrigation solutions. Seven teeth from each group were infiltrated with methylene blue to determine marginal infiltration under the stereomicroscope. The teeth were evaluated on their three thirds: cervical, middle and apical. Results: radiographs did not reveal any statistically significant difference between the mean densities of the different groups of teeth in all thirds. Scanning electron microscopy showed a statistically significant difference between the three groups of irrigation substances (p < 0,001), with greater smear layer removal from the cervical third. Optical microscopy showed that infiltration was greatest in the ethylenediaminetetraacetic acid group, followed by the citric acid group, and lowest in the control group. Conclusion: analysis of radiographic and microscopic density revealed that except for the control group, chelating agents were efficient in removing dental smear. None of the substances showed any alteration in the radiographic density of dentinal tubules.

Introducción: el tratamiento endodóntico realiza la limpieza y conformación del sistema de conductos radiculares, ya que virutas de dentina y materiales orgánicos, como los microorganismos, creadas por la acción de la instrumentación, forman el llamado barro dentinario. Objetivo: evaluar in vitro la remoción del barro dentinario y la disminución de la densidad de túbulos dentinarios, con soluciones irrigadoras quelantes. Métodos: se trata de un estudio experimental para el cual fueron seleccionados 30 dientes unirradiculares de humanos después del examen radiográfico inicial, y en el que se constató la presencia de canal único, ausencia de calcificación, reabsorción interna y tratamiento endodóntico concluido o en proceso. Luego se procedió a la instrumentación con tres diferentes soluciones irrigadoras: ácido etilenodiaminetetracético 17 %, ácido cítrico 10 % e hipoclorito de sodio 5,25 % (grupo control). Posteriormente se evaluó radiográficamente cada diente instrumentado con el uso de una escala de densidad que fue confeccionada de aluminio con diferentes marcadores de densidades. Para el análisis por microscopio electrónico de barrido se utilizaron tres dientes de cada grupo, tratados con diferentes soluciones irrigadoras. Siete dientes de cada grupo se infiltraron con azul de metileno para la lectura de la infiltración marginal en el microscopio estereoscópico. Los dientes fueron evaluados en sus tres tercios: cervical, medio y apical. Resultados: se encontró que radiográficamente no hubo diferencia estadísticamente significativa entre los promedios de las densidades de los grupos de dientes en todos los tercios. Por microscopio electrónico de barrido se encontró una diferencia estadísticamente significativa entre los tres grupos de sustancias irrigadoras (p < 0,001), en el tercio cervical la remoción del barro dentinario fue mayor. Y por microscopio óptico se observó una mayor infiltración en el grupo de ácido etilenodiaminetetracético seguido del grupo ácido cítrico y por último el grupo control. Conclusión: el análisis de la densidad radiográfica y microscópica mostró que las sustancias quelantes fueron eficientes en la remoción del barro dentinario, excepto en el grupo control. Ninguna de las sustancias demostró alteraciones de densidad radiográfica de los túbulos dentinarios.

The purpose of this study was to determine the survival and prognostic factors of patients with diffuse large B-cell lymphoma (DLBCL) of the oral cavity and maxillofacial region. Retrospectively, the clinical records of patients with a primary diagnosis of DLBCL of the oral cavity and maxillofacial region treated at the A.C. Camargo Hospital for Cancer, São Paulo, Brazil, between January 1980 and December 2005 were evaluated to determine (A) overall survival (OS) at 2 and 5 years and the individual survival percentage for each possible prognostic factor by means of the actuarial technique (also known as mortality tables), and the Kaplan Meier product limit method (which provided the survival value curves for each possible prognostic factor); (B) prognostic factors subject to univariate evaluation with the log-rank test (also known as Mantel-Cox), and multivariate analysis with Cox's regression model (all the variables together). The data were considered significant at p ≤ 0.05. From 1980 to 2005, 3513 new cases of lymphomas were treated, of which 151 (4.3%) occurred in the oral cavity and maxillofacial region. Of these 151 lesions, 48 were diffuse large B-cell lymphoma, with 64% for OS at 2 years and 45% for OS at 5 years. Of the variables studied as possible prognostic factors, multivariate analysis found the following variables have statistically significant values: age (p = 0.042), clinical stage (p = 0.007) and performance status (p = 0.031). These data suggest that patients have a higher risk of mortality if they are older, at a later clinical stage, and have a higher performance status.

The aim of this study was to identify the prognostic factors related to the survival of patients with sarcomas of the jaw treated in the Dr. Eduardo Caceres Graziani National Institute for Neoplastic Diseases, Lima, Peru. Age, gender, delay in consultation, diagnostic delay, therapeutic delay, tumor size, tumor location, facial asymmetry, pain, treatment type, and histopathological diagnosis were all evaluated as possible prognostic factors that would influence survival in those with jaw sarcomas. In the analysis, the following was used: mortality tables, Kaplan-Meier's product-limit method, log-rank, and Breslow and Tarone-Ware tests; for the prognostic factors, Cox's Regression Model was used. The overall survival rate, with the patient being free from disease at two years, was 55%, and that at five years was 45%. In the independent analysis of the prognostic factors, four variables were statistically significant in influencing survival: gender (p = 0.043), histopathologic diagnosis (p = 0.019), tumor location (p = 0.019), and treatment type (p = 0.030). According to Cox's Regression Model for the multivariate analysis, statistically significant prognostic factors were: gender (p = 0.086), tumor location (p = 0.020), and treatment type (p = 0.092). Thus, the variables of gender, tumor location, and treatment type were determined to be predictive factors for prognosis of survival.