RESUMO
This study evaluated, histologically and morphometrically, the cleaning capacity of rotary instrumentation in root canals using the Profile system with ultrasonic irrigation. Twelve single-rooted mandibular incisors were divided randomly into three groups according to the irrigation method tested. The canals in the teeth were instrumented using Orifice Shapers, taper 0.6 and 0.4 in the cervical third, and up to a #35 file in the apical third. One per cent sodium hypochlorite was used as the irrigating solution. Group I: canals were irrigated with 5 ml of solution, using a Luer-Lok syringe, between each file. Group 2: canals were irrigated with the solution and instrumented using ultrasound for I min between each file. Group 3: canals were irrigated with 5 ml of solution with Luer-Lok syringe, between each file, and final irrigation using ultrasound for 3 min. After chemo-mechanical preparation, the apical thirds of the teeth were submitted for histological processing. Morphometric analysis was performed using an optical microscope with 40x magnification and a grid. The results showed statistical difference at the 5% level between the methods used for irrigation. Rotary instrumentation with Profile system NiTi files and ultrasonic irrigation for 3 min was more effective in cleaning root canals when the different methods were compared.