Abstract: Objective: To compare the effect of glide path by using ProGlider, HyFlex EDM Glidepath File, RaCe ISO 10, PathFile, and stainless steel K file on the shaping ability of ProTaper Next in simulated root canals. Methods: A total of 40 resin blocks were divided randomly into five groups, each prepared with each glide path file. Furthermore, each canal was prepared by using ProTaper Next till X2. Preparation time for ProTaper Next was recorded. Pre- and postoperative images were superimposed and the material removal from the inner and outer canal walls beginning from 0 mm at the end point of the canal were measured using ImageJ. Centering ability of ProTaper Next was determined, accordingly. Results: Preparation times for ProTaper Next after HyFlex EDM Glidepath File and RaCe ISO 10 were significantly shorter than the others. For centering ability, at the apical portion, the transportation of HyFlex EDM Glidepath File+ProTaper Next was the least, while ststainless steeel K file+ProTaper Next was the most. At the curved portion, HyFlex EDM Glidepath File and RaCe ISO10+ProTaper Next were the least, while the transportation of ProGlider+ProTaper Next increased significantly to overwhelm that of stainless steel K file+ProTaper Next. Conclusion: Glide path exhibits significant impact on shaping ability of ProTaper Next in which the less transportation at the apical portion, the larger taper at the coronal portion, the better shaping ability of ProTaper Next.

Key words: Glide path, Shaping ability, Simulated root canals, ProTaper Next, HyFlex EDM Glidepath File