title: A comparison of curved canal instrumentation using nickel-titanium or stainless steel files with the balanced-force technique.
abstract: The Flex-R file was compared with the Onyx nickel-titanium file in respect to canal center movement and final canal area after balanced-force instrumentation. Forty-two root canals in extracted human molars were divided into two equal groups of 21, in all of which the angle of curvature ranged from 20 to 40 degrees. After mounting in a mold, each root was sectioned at two locations, providing an apical and a coronal section. Pre- and postinstrumentational 35-mm photographic slides of each section were superimposed, projected, traced, and then scanned into a computer. From these computerized pre- and postinstrumentation images, the movement of the canal center and the area of each canal were computed at both the apical and coronal sections. Results showed no significant difference in canal center movement or postinstrumentation area when Flex-R or Onyx files were used at the apical section. Coronally, the Flex-R files demonstrated more movement of the canal center. No significant correlation was found between the angle of root curvature and canal movement or the angle of root curvature and postinstrumentation canal area.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle 98195, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Harlan
authors.forename: J I
authors.initials: JI
authors.lastname: Nicholls
authors.forename: J C
authors.initials: JC
authors.lastname: Steiner
mesh_terms: D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000473:pathology; D005069:Evaluation Studies as Topic; D006801:Humans; D016014:Linear Models; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D013193:Stainless Steel; D014025:Titanium; D014092:Tooth Root / Q000473:pathology
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium