Histologic Assessment of Debridement of the Root Canal Isthmus of Mandibular Molars by Irrigant Activation Techniques Ex Vivo.

INTRODUCTION: This study aimed to evaluate the efficacy of a new irrigation system (EndoIrrigator Plus; Innovations Endo, Nasik, India) using a histologic method ex vivo. METHODS: Mandibular molars with a normal pulp extracted for periodontal reasons (N = 68) were assessed for the presence of an isthmus using cone-beam computed tomographic imaging. Root canals of the included molars (n = 40) were instrumented up to a ProTaper F2 instrument (Dentsply Maillefer, Baillagues, Switzerland) using 3% sodium hypochlorite as irrigant in a closed apical design. Final irrigation delivery/activation was performed as follows (n = 10): group 1, syringe irrigation; group 2, apical negative pressure delivery with continuous warm activated irrigation and evacuation system (CWAIS); group 3, manual dynamic agitation (MDA); and group 4, passive ultrasonic irrigation (PUI). Untreated teeth (n = 5) served as histologic controls. The isthmus regions (1, 3, and 5 mm from the apex) were analyzed by hematoxylin-eosin stain to calculate the percentage of remaining pulp tissue (RPT) relative to the area of the isthmus. Results were analyzed using the Mann-Whitney U test (P = .05). RESULTS: CWAIS showed significantly less RPT than the other groups at all 3 root levels (P < .05). MDA showed significantly less RPT at 1 and 3 mm from the apex compared with PUI and syringe irrigation (P < .05). There was no significant difference between PUI and MDA at the 5-mm level (P > .05). CONCLUSIONS: None of the methods could completely clean the isthmus. CWAIS left behind the least amount of RPT.