RESUMO
This study compared the shaping ability of nickel-titanium rotary files with different rake angle and radial land. The nickel-titanium files used in this study were Profile(Dentsply, Maillefer, Ballaigues, Switzerland), Hero 642(Micromega, Besancon, France), and K3(SybronEndo, Glendora, Ca, USA) file. Resin blocks substituted for root canals. 36 resin blocks were divided into 3 groups with 12 canals each. The time for canal preparation was recorded. The images of pre- and postoperative resin canal were scanned and those were superimposed. Amounts of canal deviation, total canal widths, inner canal widths, and outer canal widths were measured at apical 1, 2, 3, 4, 5, 6, and 7mm levels. The amount of canal deviation was the smallest in Profile group, and the time for canal preparation was the shortest in Hero 642 group. K3 group resulted in competent characteristics in both measurements. Positive rake angle seemed to result in fast shaping of root canal and radial land guide the instrument in center of the canals and around curvatures. Radial land also tended to reduce the sense of screwing into the root canal. The proper selection of the nickel-titanium file based on the knowledge about file design is needed for the safer, simpler and faster root canal therapy.