Evaluation of the efficacy of filling material removal and re-filling after different retreatment procedures

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.

The effectiveness of passive ultrasonic irrigation and the easy-clean instrument for removing remnants of filling material

“…This is in agreement with previous studies that have also demonstrated that no additional cleaning technique during endodontic retreatment was able to completely remove the material from the root canals. [ 7 8 9 10 11 12 13 14 15 16 ] The percentage of filling material remaining after the use of PUI and easy-clean agitation systems was 14%–21%, and there was no statistically significant difference between the groups. Although no system completely removed the remaining obturator material, the filling material was significantly reduced when compared to the initial retreatment step, demonstrating the importance of performing an additional cleaning step during retreatment of the RCS.…”

“…These results are in agreement with Grischke et al . [ 10 ] and Castro et al .,[ 11 ] who observed via different microscopy techniques that PUI improved the removal of remnant gutta-percha and AH Plus sealer during retreatment. In addition, our results are in accordance with that of Cavenago et al .,[ 12 ] Bernardes et al .,[ 13 ] Silveira et al .,[ 14 ] and Kaloustian et al .,[ 15 ] who observed via micro-CT that PUI significantly improved the removal of gutta-percha and AH Plus, AH 26, and Pulp Canal sealers remaining in incisors and mandibular molars.…”

“…[ 5 6 ] However, the efficacy of PUI for removing remnant filling materials during retreatment remains controversial. [ 7 8 9 10 11 12 13 14 15 ] Da Rosa et al . [ 8 ] and Barreto et al .…”

“…[ 10 ] and Castro et al . [ 11 ] observed via different microscopy techniques that PUI improved the removal of remnant gutta-percha and AH Plus sealer during retreatment. Moreover, some authors observed via micro-CT that PUI significantly improved the removal of remnant gutta-percha and AH Plus, AH 26, and Pulp Canal Sealer sealers in mandibular incisors and molars.…”

Critical analysis of research methods and experimental models to study removal of root filling materials

“…Commonly, they are just taken together as a whole. Confocal laser scanning microscopy is a method that can be used to specifically assess the removal of root canal sealers (Canali et al, 2019; de Castro et al, 2018; Kim et al, 2015; Kok et al, 2014; Rached‐Júnior et al, 2014a, 2014b). With this research method, when the tooth samples were first root filled, a florescent dye (0.1% rhodamine B) is added to the root canal sealer.…”