Histologic evaluation of canal and isthmus debridement efficacies of two different irrigant delivery techniques in a closed system.

Introduction: This study compared canal and isthmus debridement efficacies between side-vented needle irrigation (SNI) and continuous ultrasonic irrigation (CUI) in the mesial root of mandibular first molars with narrow isthmuses using a closed-canal design.

Methods: Micro-computed tomography scanning was used to select 20 teeth, each containing a narrow isthmus. Each root was sealed at the apex; embedded in polyvinylsiloxane to simulate a closed-canal system; and instrumented to size 40, 0.