title: The challenge of C-shaped canal systems: a comparative study of the self-adjusting file and ProTaper.
abstract: BACKGROUND
  C-shaped canals are anatomic features that present the clinician with both diagnostic and operational challenges. The aim of this study was to compare the efficacy of the Self-Adjusting File (SAF; ReDent, Ra'anana, Israel) in shaping C-shaped canals with that of the rotary ProTaper file system (Dentsply-Maillefer, Ballaigues, Switzerland).
  
  
  METHODS
  Sixteen mandibular second molars and 4 maxillary second molars with C-shaped canals were obtained, originating from native Chinese population. They were divided into 2 equal groups of 10 teeth each, based on similar canal morphology as presented in preliminary micro-computed tomography-derived images. One group was shaped using the SAF, whereas the other was shaped using the ProTaper file system. Reconstructed micro-computed tomographic images before and after treatment were superimposed over each other, and the percentage of the canal wall unaffected by the procedure was calculated. Comparison of the 2 groups for this parameter was performed using the Student t test.
  
  
  RESULTS
  When treated with the SAF, 41% ± 14% of the canal walls remained unaffected by the procedure, whereas 66% ± 6% of the wall area was unaffected when using ProTaper, which was significantly higher than that of the SAF-treated group (P < .001).
  
  
  CONCLUSIONS
  The SAF was more effective than the ProTaper file system in shaping the walls of C-shaped root canals.
authors.affiliation: Department of Endodontics, Hebrew University and Hadassah School of Dental Medicine, Jerusalem, Israel. mishasol@gmail.com
authors.forename: Michael
authors.initials: M
authors.lastname: Solomonov
authors.forename: Frank
authors.initials: F
authors.lastname: Paqué
authors.forename: Bing
authors.initials: B
authors.lastname: Fan
authors.forename: Yuval
authors.initials: Y
authors.lastname: Eilat
authors.forename: Louis H
authors.initials: LH
authors.lastname: Berman
mesh_terms: D002614:Chelating Agents / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000473:pathology*; D004492:Edetic Acid / Q000627:therapeutic use; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008963:Molar / Q000473:pathology; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D014732:Vibration; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D002614:Chelating Agents; D012388:Root Canal Irrigants; D004492:Edetic Acid; D012973:Sodium Hypochlorite