ABSTRACT
BACKGROUND: Endodontic instruments including the nickel-titanium (NiTi) instruments produce debris and smear layer during instrumentation. The study was carried out to evaluate and compare the cleaning effectiveness of root canal preparation using three different rotary NiTi instrumentation systems - ProTaper Universal, K3 and Mtwo by means of scanning electron microscopy (SEM). METHODS: Thirty-six freshly extracted permanent mandibular molars were randomly divided into four groups: ProTaper Universal, K3, Mtwo system and control group. The mesiobuccal canal was cleaned and shaped with rotary instruments. The intracanal irrigant used after each instrument was 3 mL of 3% sodium hypochlorite (NaOCl). After the cleaning and shaping was completed, a 1-min 17% ethylenediaminetetraacetic acid rinse was followed by a final NaOCl rinse. All samples were decoronated. Mesial roots were sectioned buccolingually and examined under SEM at 500× magnification in three areas of root canal. Canal walls were quantitatively evaluated using a five-score evaluation scale. Statistical analysis was done using Kruskal-Wallis test, Fisher's exact test and weighted kappa. RESULTS: Completely clean canals were not found in any of the groups. The mean value of debris score for ProTaper, K3 and Mtwo was 2.35, 2.41 and 2.22 respectively. There was no statistically significant difference between the three tested groups (P = 0.237). The apical thirds of the canal was found to be significantly less clean than coronal and middle thirds irrespective of the system used. CONCLUSIONS: There was no statistically significant difference between the three tested groups - ProTaper, K3 and Mtwo in cleaning different regions of the canal - coronal, middle and apical.
