Curved versus straight root canals: the benefit of activated irrigation techniques on dentin debris removal

Objective. The aim of this study was to compare the efficacy of hydrodynamic and ultrasonic-activated irrigation to conventional syringe irrigation in removing dentin debris in straight and curved root canals. Study design. Twelve human teeth were selected for study. The root canals of 6 single-rooted premolars with straight canals and 6 molar roots with curved canals were prepared to a size of 45 and split longitudinally. To simulate canal irregularities, 3 standardized holes were cut in 1 canal wall. The canals and holes were then covered with debris. After reassembly, 3 irrigation techniques were compared: syringe irrigation, hydrodynamic irrigation, and ultrasonic irrigation. The amount of debris that remained was evaluated microscopically and graded with a 4-score system. Results. The hydrodynamic and ultrasonic irrigation techniques were significantly (P < .001) more efficient as compared with syringe irrigation in both the straight and curved root canals. Ultrasonic irrigation demonstrated a higher efficiency in the straight root canals (P < .01), whereas hydrodynamic irrigation was more efficient in the curved canals (P < .01). Conclusions. In the straight canals, ultrasonic irrigation was the most effective, but in the curved root canals, hydrodynamic irrigation was superior. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:529-534)