Methods: A total of 34 MB canals of maxillary first molars with angle of curvature (20-40) degrees were divided into 4 groups. Samples in group A (n=15) were prepared with Reciproc #25 and taper of 0.08. Samples in group B (n=15) were by iRace sequence (#15/0.06, #25/0.04 taper).Two samples served in negative and positive control groups. Final irrigation consisted of 17% EDTA and 5.25%NaOCl followed by distilled water. The specimens were examined under SEM and scored on the basis of numerical evaluation scale for the amount of remained debris and smear layer in 3 different thirds of the canals. Data were subjected to Kruskal-Wallis test.
Results: There was no significant difference in regard to the smear layer between the two groups A and B. Reciproc left significantly less debris in apical and middle third of the canal (P<0.03, P<0.07 respectively).
Conclusions: Based on the findings of the present study Reciproc can result in clean walls in apical and middle thirds of maxillary mesiobuccal canals.