Abstract This study analyzed the influence of different retreatment protocols on amount of remaining filling material and amount of new sealer after endodontic retreatment. Forty mandibular molars with curved mesial roots were prepared with ProTaper Universal system, and filled with AH Plus sealer mixed with 0.1% rhodamine B and gutta-percha. After 7 days, the specimens were randomized according to the retreatment protocol (n = 10): ProTaper Retreatment System (PTR); PTR+Orange Oil (PTR+OO); PTR+Passive Ultrasonic Irrigation (PTR+PUI). No retreatment was performed in the control group (CG). After retreatment, the root canals were filled with AH Plus mixed with 0.1% fluorescein and gutta-percha. Samples were evaluated under confocal laser scanning microscopy and analyzed using Image J software. Data were analyzed using Kruskal-Wallis and Dunn tests (p < 0.05). Regarding presence of residual filling, the Kruskal-Wallis test indicated no differences among the different retreatment techniques in the perimeter and the isthmus analyses (p > 0.05); however, PTR+PUI was associated with a lesser amount of residual filling material in the canal area analysis (p < 0.05). In evaluating the new filling, the perimeter analysis showed a lesser amount of new endodontic sealer in the PTR group (p < 0.05). Moreover, the PTR+PUI group presented a significantly greater amount of new endodontic sealer in the canal area analysis (p < 0.05). There was no difference among groups in the isthmus analysis (p > 0.05). It can be concluded that PTR associated to PUI yielded better results in removing root canal filling material from the canal area. However, none of the protocols resulted in root walls completely free of remnants.

There are no studies in the literature reporting the prevalence of root canal ramifications in samples of lower incisors in the population of northern Brazil. The knowledge of the usual endodontic morphology and its possible anatomical variations is important. The aim of this study was to evaluate the prevalence of canals in the lower incisors in the population of northern Brazil using the descaling and diaphanization method. In addition, external measurements were performed and the direction of the apical foramen was observed. One hundred teeth were used for this study, and 18 % of them had two canals, with type 3 being the most prevalent, and the lowest incidence was type 5. The average length of the teeth was 18.5 mm, with 76.31 % of the teeth having a foramen that coincided with the long axis of the tooth. Prior knowledge of such changes should be considered before endodontic therapy.

No hay estudios en la literatura que reporten la prevalencia de las ramificaciones del canal radicular en muestras de incisivos inferiores en la población del Norte de Brasil. El conocimiento de la morfología dentaria en endodoncia y sus posibles variaciones anatómicas es importante. El objetivo del estudio fue evaluar la prevalencia de canales en los incisivos inferiores en la población del Norte de Brasil utilizando el método de descalcificación y diafanización. Además, se realizaron mediciones externas y se observó la dirección del foramen apical. Cien dientes fueron utilizados en este estudio, 18 % tenían dos canales, siendo el tipo 3 el más prevalente, y solo un diente presentó el tipo 5. La longitud promedio de los dientes fue de 18,5 mm, de los cuales en el 76,31 % de éstos se observó un foramen que coincidió con el eje longitudinal del diente. El conocimiento previo de éstas variaciones debe ser considerado antes de la terapia endodóntica.