title: Shaping abilities of two different engine-driven rotary nickel titanium systems or stainless steel balanced-force technique in mandibular molars.
abstract: The purpose of this study was to compare apical transportation, working-length changes, and instrumentation time by using nickel-titanium (Ni-Ti) rotary file systems (crown-down method) or stainless steel hand files (balanced-force technique) in mesiobuccal canals of extracted mandibular molars. The curvature of each canal was determined and teeth placed into three equivalent groups. Group 1 was instrumented with Sequence (Brasseler USA, Savannah, GA) rotary files, group 2 with Liberator (Miltex Inc, York, PA) rotary files, and group 3 with Flex-R (Union Broach, New York, NY) files. Pre- and postoperative radiographs were superimposed to measure loss of working length and apical transportation as shown by changes in radius of curvature and the long-axis canal angle. Sequence rotary files, Liberator rotary files, and Flex-R hand files had similar effects on apical canal transportation and changes in working length, with no significant differences detected among the 3 groups. Hand instrumentation times were longer than with either Ni-Ti rotary group, whereas the rotary NiTi groups had a higher incidence of fracture.
authors.affiliation: Division of Endodontics, University of Minnesota School of Dentistry, Minneapolis, MN, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Matwychuk
authors.forename: Walter R
authors.initials: WR
authors.lastname: Bowles
authors.forename: Scott B
authors.initials: SB
authors.lastname: McClanahan
authors.forename: Jim S
authors.initials: JS
authors.lastname: Hodges
authors.forename: Igor J
authors.initials: IJ
authors.lastname: Pesun
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D007091:Image Processing, Computer-Assisted; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D009532:Nickel / Q000737:chemistry*; D011859:Radiography; D012399:Rotation; D013193:Stainless Steel / Q000737:chemistry*; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*