title: Comparison of dentine removal using V-taper and K-Flexofile instruments.
abstract: OBJECTIVE
  To compare the dentine removal ability of V-Taper and K-Flexofile instruments in mesiobuccal canals of extracted mandibular first molar teeth.
  
  
  METHODS
  Preoperative images of 40 mesiobuccal canals of mandibular first molars (with a curvature between 20° and 35°) were obtained at 2, 4.5, and 7 mm from the root apices by CT-scan and divided into two groups. Group F was prepared with K-Flexofiles and Gates Glidden drills and Group V with V-Taper Ni-Ti rotary and stainless steel hand instruments. Post-instrumentation images were then obtained and compared with the preoperative images. The ratio of dentine removal based on pre- and postoperative images was calculated, and data was analysed by anova and Tukey post hoc test.
  
  
  RESULTS
  In group F in the coronal sections, the least ratio of the dentine removal to the initial root thickness was on the buccal aspect (15.14% ± 6.72), and the greatest ratio was found on the distolingual (29.38% ± 8.19). In group V in the coronal, the least ratio of the dentine removal to the initial root thickness was on the buccal aspect (9.81% ± 3.26); the greatest ratio was found on the distolingual surface in the coronal sections (34.38% ± 10.51). In the middle sections, the least ratio was on the buccal (10.51% ± 3.39) and the greatest on the distolingual aspects (27.46% ± 12.34) of the roots. In the apical sections, the amount of the dentine removed from the mesial and distal surfaces in group V was significantly more than group F (P < 0.01).
  
  
  CONCLUSIONS
  The distolingual aspect of the root canal is a danger zone for the mesiobuccal canal of the mesial root in mandibular molar teeth, and preparation of that area should be performed with caution. Except the apical part of the canal, no significant difference was found between the two preparation files or techniques used. Apart from the apical part of the canal, neither instrument maintained the original shape of the coronal and middle parts of the canal.
authors.affiliation: Department of Endodontics, Dental branch, Islamic Azad University, Tehran, Iran. akhlaghinahid@yahoo.com
authors.forename: N M
authors.initials: NM
authors.lastname: Akhlaghi
authors.forename: R
authors.initials: R
authors.lastname: Kahali
authors.forename: A
authors.initials: A
authors.lastname: Abtahi
authors.forename: S
authors.initials: S
authors.lastname: Tabatabaee
authors.forename: P
authors.initials: P
authors.lastname: Mehrvarzfar
authors.forename: M
authors.initials: M
authors.lastname: Parirokh
mesh_terms: D000328:Adult; D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging / Q000473:pathology*; D003804:Dentin / Q000000981:diagnostic imaging / Q000473:pathology*; D004867:Equipment Design; D006801:Humans; D008334:Mandible; D008422:Materials Testing; D008875:Middle Aged; D008963:Molar; D009532:Nickel / Q000737:chemistry; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012399:Rotation; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013193:Stainless Steel / Q000737:chemistry; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D014057:Tomography, X-Ray Computed; D019227:Tooth Apex / Q000000981:diagnostic imaging / Q000473:pathology; D014092:Tooth Root / Q000000981:diagnostic imaging / Q000473:pathology; D019415:Torque
chemical_list: D003722:Dental Alloys; D012388:Root Canal Irrigants; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite