Cleaning Effectiveness and Shaping Ability of Rotary Protaper

Objective:To compare the cleaning and shaping ability of rotary Protaper, stainless steel hand K-Flexofile and rotary GT during the preparation of curved root canals in vitro.Methods: 45 canals with curvatures ranging between 25 and 41 were divided into three groups.The groups were balanced according to the angel and the radius of canal curvature,canals were prepared by Protaper or GT using a crown-down technique or by K-Flexofile using double flared technique.After each instrument, canals were flushed with 2.5%NaOCL.By double exposure radiographic technique, the incidence of apical transportation was analysed with Fisher's exact test .After splitting the roots longitudinally,the amout of debris and smear layer were quantified using a scanning electron microscope .The data established for scoring the debris and the smear layer were separately recorded and analysed with the Kruskal-Wallis'test. Results:None of the K-Flexofile and Protaper but 2 GT separated. For debris removal,Protaper achived better results than GT (P<0.05) and K-Flexofile (P>0.05); For smear layer removal,K-Flexofile achived better results than Protaper(P>0.05) and GT(P>0.05).Protaper and GT both maintain the original curvature significantly better than K-Flexofile(P<0.05).For the time taken to prepare the canals, Protaper was significantly shorter than GT(P<0.05)and K-Flexofile(P<0.001).Conclusions:Protaper allowed significantly better removal of debris than GT and K-Flexofile,while K-Flexofile achived relatively better removal of smear layer than Protaper and GT; Protaper and GT maintained the original curvature much better and took much shorter time to prepare canals than K-Flexofile; Protaper took shorter time to shape canals and showed lower incidence of separation than GT.