RESUMO
AIM: To compare the effectiveness of two Ni-Ti systems and hand files for removing gutta-percha and sealer from root canals. METHODOLOGY: The root canals of 60 single-rooted human teeth were prepared, filled with gutta-percha and sealer (Pulp Canal Sealer; SybronEndo, Orange, CA, USA). Specimens were then divided into three groups (n=20), and root filling material was removed using MTwo Retreatment Files (group 1); R-Endo (group 2); K-files and Gates-Glidden drills (group 3). After retreatment, the efficacy of each technique was assessed using radiographs that were later digitized and the images analysed using AutoCAD 2004. The percentage of residual gutta-percha was calculated for the whole canal as well as for the coronal, middle and apical thirds. Time required, apically extruded debris and the number of fractured instruments were also recorded. Data were statistically analysed using Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: All instrumentation techniques left gutta-percha and sealer remnants inside the root canals. Ni-Ti systems were significantly faster (P < 0.05) than the manual technique and significantly more effective (P < 0.05) in removing gutta-percha particularly from the middle and apical thirds of the root canal. R-Endo instrumentation was significantly more effective (P < 0.05) than MTwo retreatment files in removing gutta-percha from the middle and apical thirds. R-Endo instruments were associated with the least number of cases of apical extrusion. One MTwo instrument fractured. CONCLUSIONS: The Ni-Ti systems were more effective and faster than hand files, although all techniques left gutta-percha and sealer remnants on the root canals.
