Effect of Maintaining Apical Patency on Irrigant Penetration into the Apical Third of Root Canals When Using Passive Ultrasonic Irrigation: An In Vivo Study

Introduction: The complex anatomy of the root canal system has been shown to limit the penetration of irrigating solutions into the apical third; hence, the aim of this study was to determine whether the use of a patency file is related to the presence of a radiopaque irrigating solution in the apical third of human root canals after using passive ultrasonic activation in vivo. Methods: Forty human root canals were randomly divided into two groups. Apical patency was maintained in one group (n = 21) during shaping and cleaning procedures with a no. 10 K-file 1 mm beyond the working length (WL) but not in the other group (n = 19). In both groups, the canals were shaped with the Pro Taper system (Dentsply-Maillefer, Ballaigues, Switzerland). Irrigation was performed with 1 mL of a solution prepared with a radiopaque contrast medium and sodium hypochlorite 5.25%, and then passive ultrasonic irrigation (PUI) was applied after the shaping procedure. Digital images were taken; and a calibrated reader determined the presence or absence of the irrigating solution in the apical third. Results: There were significantly more canals with irrigant in the apical third after PUI when apical patency was maintained with a no. 10 file 1 mm beyond the WL than when apical patency was not maintained throughout the cleaning and shaping procedures (P = .02). Conclusions: Maintaining apical patency and then using PUI improves the delivery of irrigants into the apical third of human root canals. (1 Endod 2011;37:1276-1278)