title: Effect of early coronal flaring on working length change in curved canals using rotary nickel-titanium versus stainless steel instruments.
abstract: This in vitro investigation examined pre- and postinstrumentation working length (WL) measurements in curved root canals. The conditions compared were combinations of (a) stainless steel hand files + Gates Glidden drills (SS) versus nickel-titanium rotary files (Ni-Ti); and (b) early coronal flaring (flaring completed before WL determination) versus late coronal flaring (flaring completed after WL determination). Coronal flaring was accomplished for the SS group using Gates Glidden drills and for the Ni-Ti group using rotary Ni-Ti files (n = 15/group). WL was determined before coronal flaring, immediately after coronal flaring, and again after canal preparation. Results indicated that WL decreased for all canals as a result of canal preparation. The mean decrease in WL was significantly greater for the SS group (-0.48 mm +/- 0.32) than for the Ni-Ti group (-0.22 mm +/- 0.26). Less change in WL occurred in both groups when initial WL was determined after coronal flaring (SS: -0.12 mm +/- 0.13, Ni-Ti: -0.14 mm +/- 0.25).
authors.affiliation: Department of Endodontology, OHSU School of Dentistry, Portland, Oregon 97201, USA.
authors.forename: R Dean
authors.initials: RD
authors.lastname: Davis
authors.forename: J Gordon
authors.initials: JG
authors.lastname: Marshall
authors.forename: J Craig
authors.initials: JC
authors.lastname: Baumgartner
mesh_terms: D000704:Analysis of Variance; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D006801:Humans; D009532:Nickel; D009811:Odontometry; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods*; D013193:Stainless Steel; D014025:Titanium
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium