Abstract:

Objective　Curved canal preparation is much difficult in root canal therapy(RCT). Step back technique and rou- tine technique are still regularmethods in curved canal preparation. The purpose of this studywas to introduce a newmethod—re- verse flaring technique, and to investigate its preparation efficiency in intermediate-curvature canals.Methods　48 cases of lower first molars RCTwere collected, whichwere firsttreated because of pulpitis or apical periodontitis inWest China College of Stoma- tology, Sichuan University from Nov. 2001 to Aug. 2003, mesial canal curvature was intermediate (30°~60°), determined by Schineider method. Caseswere divided intotwo groups, in reverse flaringtechnique group, canal preparation in 27 caseswere fin- ished by reverse flaring technique, 21 cases by step back technique as control. In working length determination and fitting master cone stages, cases in two groupswhich fit full working lengthwere recorded, determined by radiogragh, and analyzed byχ2test. Results　Inworking length determination stage, caseswhich fit full working length in reverse flaring technique groupwere signifi- cantly more than that of step back technique group (P<0·05), in fittingmaster cone stage, caseswhich fit fullworking length in reverse flaring technique group were also significantly more than that of step back technique group(P<0·05).Conclusion　In working length determination stage, cases which fit full working length in reverse flaring technique group were significantly more than that of step backtechnique group (P<0·05), in fittingmaster cone stage, caseswhich fit fullworking length in reverse flar- ing technique group were also significantly more than that of step back technique group(P<0·05).

Key words: root canal therapy, canal preparation, canal curvature, reverse flaring lechnique