title: Comparison of root canal transportation induced by three rotary systems with noncutting tips using computed tomography.
abstract: OBJECTIVE
  The purpose of this study was to compare the shaping ability (apical transportation and straightening) of 3 nickel-titanium rotary instruments (ProTaper Universal, Hero 642 Apical, FlexMaster) with noncutting tips in curved root canals of extracted human teeth using cone beam computed tomography (CBCT).
  
  
  METHODS
  Sixty mesiobuccal root canals of maxillary molars with curvatures of 25° to 47° were equally divided into 3 groups and embedded in silicone impression material. The root canals were scanned using CBCT (Next Generation i-CAT) and after scanning working length was determined with a hand file to preserve the original curvature. After preparation, teeth were placed into their original positions on the silicone impression material and postinstrumentation scans were performed using the same parameters (4-cm field of view at 0.125-mm voxel). Pre- and postinstrumentation images obtained from root cross-sections located 2, 3, and 4 mm above the apical foramen were compared using Adobe Photoshop software. Transportation was measured by superimposition of final and initial images. Any distance (mm) between prepared and anatomic canal centers was defined as apical transportation. Canal curvatures were measured before and after instrumentation using computed tomography and images were exported to ImageJ software. Differences in the degree and radius of curvature were regarded as straightening. Data were analyzed by ANOVA.
  
  
  RESULTS
  Mean transportation values were 0.10 ± 0.03 mm for ProTaper Universal, 0.09 ± 0.03 mm for Hero 642 Apical, and 0.07 ± 0.02 mm for FlexMaster, and the differences were not significant. Mean values for straightening among the groups were not significantly different (P > .05). The performances of all instruments were similar.
  
  
  CONCLUSIONS
  Apical transportation occurred with all the instruments despite their noncutting tips.
authors.affiliation: Faculty of Dentistry, Department of Operative Dentistry and Endodontics, Dicle University, Diyarbakir, Turkey. senemygt@hotmail.com
authors.forename: Senem Yiğit
authors.initials: SY
authors.lastname: Özer
mesh_terms: D054893:Cone-Beam Computed Tomography; D003722:Dental Alloys; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D004867:Equipment Design; D006801:Humans; D008437:Maxilla; D008963:Molar; D009532:Nickel; D009811:Odontometry; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D014025:Titanium; D019227:Tooth Apex / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium