Effectiveness of complementary irrigation routines in debriding pulp tissue from root canals instrumented with a single reciprocating file.

Aim: To compare histologically the debridement efficacy of four irrigation techniques in root canals instrumented with a reciprocating single file. Methodology: From recently extracted premolars with vital pulp, 68 were selected and classified as having round canals (mesiodistal diameter similar to buccolingual) or oval‐shaped canals (mesiodistal diameter 2.5 times larger than buccolingual) (n = 32, each) by means of bidirectional radiographs. Four additional uninstrumented samples served as histological controls. The root canals of the specimens were accessed and then instrumented with Reciproc R25® and further assigned to one of four experimental groups according to the complementary irrigation technique: Group I, conventional syringe; Group II, passive ultrasonic irrigation; Group III, manual dynamic activation (MDA); and Group IV, EndoActivator®. Roots were then demineralized and the apical 3 mm was multi‐sliced and processed for histologic examination. The percentage of residual pulp tissue was calculated at each cross section. Kruskal–Wallis and Mann–Whitney tests were used to evaluate the effects of irrigation technique, root canal shape and level of cross section on the percentage of residual pulp tissue (P < 0.05). Results: Irrigation technique and root canal shape significantly influenced the percentage of residual pulp tissue (P < 0.05) of canals instrumented with the R25 instrument. Percentage of residual pulp tissue was significantly less using ultrasonic irrigation (P < 0.05), but there was no difference between other irrigation techniques (P > 0.05). Round canals retained significantly less percentage of residual pulp tissue compared to oval‐shaped canals (P = 0.001). At 3 mm, there was less pulp tissue compared to levels 2 and 1 mm (P < 0.05). Conclusions: In canals instrumented with R25 files, ultrasonic irrigation was more effective in removing pulp tissue in the apical level, especially for the debridement of oval‐shaped canals. [ABSTRACT FROM AUTHOR]