Effects of various irrigation/aspiration protocols on cleaning of flattened root canals

This study aimed to evaluate, by means of scanning electron microscopy (SEM), the cleaning of flattened root canals, varying irrigation/aspiration protocols during biomechanical preparation. Thirdy human mandibular incisors were distributed into three groups (n = 10) according to the aspiration/irrigation protocols: conventional, conventional + brush, and apical negative pressure irrigation. Irrigation procedure was performed with 5 mL of 1% NaOCl at each change of instrument; final irrigation was conducted with 17% EDTA for 5 min. After biomechanical preparation, the roots were sectioned and prepared for SEM analysis. The images obtained were evaluated under 35× and 1,000× magnification by three calibrated examiners, following a double-blind design. All data were analyzed using Kruskal–Wallis and Dunn’s post hoctests (α = 0.05). Canals wherein the conventional method and apical negative pressure irrigation were employed revealed less debris, statistically different from the conventional + brush group (p < 0.05). Regarding the presence of smears, apical negative pressure irrigation was more effective in cleaning, showing lowest scores (p < 0.05), compared with the other tested protocols. Comparing each root canal third revealed that the apical portion was difficult to clean as all the tested protocols showed similar high scores (p > 0.05), both for the presence of debris and smear layer. In conclusion, although none of the studied irrigation/aspiration protocols have completely cleaned flattened root canals, apical negative pressure irrigation was more effective in smear layer removal, whereas the conventional + brush protocol was the least effective in removing the debris and smear layer.

Activación sónica versus ultrasónica de EDTA al 10% para remoción de barrillo dentinario en el tercio apical del canal radicular / Sonic versus ultrasonic activation of 10% EDTA for smear layer removal in the root canal apical third

El objetivo de este estudio fue evaluar la efectividad de la activación sónica y ultrasónica del ácido etilendiaminotetraacético (EDTA) al 10% para remover barrillo dentinario en el tercio apical y el grado de erosión producido sobre las paredes del canal radicular. Se realizó un estudio cuantitativo experimental in vitro. Se instrumentaron 40 dientes manualmente con la técnica step-back hasta lima maestra número 55 y fueron asignados a 4 grupos según protocolo de irrigación final: I: agua destilada estéril sin activación, II: EDTA 10% sin activación por 30 segundos, III: EDTA 10% activado sónicamente por 30 segundos y IV: EDTA 10% activado ultrasónicamente por 30 segundos. Las muestras fueron observadas en MEB a una magnificación de 5000X. Se evaluó la presencia de barrillo dentinario remanente y grado de erosión según criterios de Torabinejad et al. Para el análisis estadístico se utilizó la prueba de Kruskal-Wallis y Post Hoc de Tukey con un nivel de significancia 5% (p=0,05). El grupo I (agua sin activación) presentó mayor cantidad de barrillo que el resto de los grupos (p<0,01). En cuanto a la presencia de barrillo, entre los grupos II (EDTA sin activación), III (EDTA con sonido) y IV (EDTA con ultrasonido) no hubo diferencias estadísticamente significativas. En cuanto a la erosión, el grupo II presentó una mayor erosión que el resto siendo significativa con los grupos I y III (p=0,006). Entre los grupos I, III y IV no hubo diferencias estadísticamente significativas. La activación sónica y ultrasónica del EDTA 10% no produjo una remoción de barrillo significativamente superior al compararlo con la irrigación convencional, pero sí hubo diferencias en cuanto a erosión, siendo menor con la activación sónica

The purpose of this study was to observe the effect of passive sonic and ultrasonic irrigation with 10% Ethilenediaminotetracethic acid (EDTA) on smear layer of the apical third of instrumented root canals as well as the level of erosion produced on the canal walls. For this quantitative experimental in vitro study 40 teeth were hand instrumented with step back technique until master file num 55 and divided in four groups according to the final irrigation protocol: I: distilled water without activation, II: 10% EDTA for 30 seconds without activation, III: 10% EDTA sonic activated for 30 seconds, IV: 10% EDTA ultrasonic activated for 30 seconds. Samples were prepared for MEB observation at 5000X. The presence of smear layer and erosion on dentine walls was quantified according to Torabinejad et al. criteria. Data were submitted at Kruskal-Wallis test and Tukey Post Hoc with a significance level of 5% (P=0.05). When evaluating the smear layer presence, there were no statistically significant differences between the groups II, III and IV. Group I had a highest amount of smear layer (p<0.01). As for erosion, group II showed higher erosion than the others, being significant with groups I and III (p=0.006). Among groups I, III and IV there were not statistically significant differences. Sonic and ultrasonic activation of EDTA 10% did not produce a significantly superior removal of smear layer when compared with conventional irrigation. Erosion of root canal walls was significantly lower after sonic activation