Resumo

BRAITT, Antônio Henrique; CUNHA, Rodrigo Sanches; MARTIN, Alexandre Sigrist de  e  BUENO, Carlos Eduardo da Silveira. Evaluation of cleaning efficacy of a nickel-titanium rotary system, with or without 17% EDTA passive ultrasonic activation: a scanning electron microscopic study. RSBO (Online) [online]. 2012, vol.9, n.1, pp. 38-43. ISSN 1984-5685.

Introduction: The goal of endodontic instrumentation is to promote root canal cleaning and shaping to prepare it for the subsequent three-dimensional filling. Objective: The aim of this study was to evaluate, ex vivo, root canal cleaning ability executed by nickel-titanium rotary system instrumentation and this same system plus ultrasound passive activation of 17% EDTA, through SEM. Material and methods: Seventy upper second single-rooted human bicuspids were used. All teeth presented a single root canal, flattened towards buccal-palatal direction. The teeth were randomly separated into 3 groups. Group 1 (n = 30), had the canals instrumented by using the original operative sequence of ProTaper Universal System, up to instrument #F3. In this group, 5 ml of 5.25% sodium hypochlorite was employed as irrigant, every each instrument change. After group 1 instrumentation, root canals were irrigated with 5 ml of 17% EDTA, which was kept inside the canal for 3 minutes. Next, a final irrigation with 5 ml of 5.25% NaOCl was performed to remove the smear layer in suspension. Group 2 (n = 30) had the canals instrumented by the same system and up to the same instrument size. It was used 5.0 ml of 5.25% NaOCl as irrigant substance every each instrument change. In group 2, however, 17% EDTA (5 ml) was applied through ultrasonic passive activation for 1 minute, and then leaving the substance for 2 minutes within root canal.A final irrigation and with 5.25% NaOCl was also performed. Group 3 (n = 10) was the control group, where the canals were not instrumented and irrigation was executed with saline solution. After that, the teeth were cut into their long axis, metalized and taken for SEM analysis, at x2000 magnification. Each tooth's cervical, middle and apical thirds were observed. The cleaning quality of root canal's walls was observed by the images analyzed by three examiners. Results: Data were statistically analysed by analysis of variance and Tukey test, with a significance level of 5%. The control group showed an average score of the presence of smear layer of 3.41; group 1 (ProTaper) of 2.34; and the group 2 (ProTaper+Ultrassound) of 0.60. Conclusion: None of the studied preparation techniques promoted the total cleaning of the root canal walls. The addition of the ultrasound passive activation, after rotary instrumentation, promoted an increase of the smear layer removal, improving the cleaning of root canal wall. The apical third obtained the smallest cleaning rate, regardless of the technique employed.

Palavras-chave : irrigation; rotary instrumentation; ultrasound..