title: Comparing the Coronal Flaring Efficacy of Five Different Instruments Using Cone-Beam Computed Tomography.
abstract: BACKGROUND
  Fearless removal of tooth structure during canal preparation and shaping has negative effects on the prognosis of treatment. On the other hand, sufficient pre-enlargement facilitates exact measurement of the apical size. The present in vitro study aimed to compare the efficacy of Gates-Glidden drills, K3, ProTaper, FlexMaster and RaCe instruments in dentin removal during coronal flaring using cone-beam computed tomography (CBCT).
  
  
  METHODS
  A total of 40 mandibular molars were selected and the coronal areas of their mesiobuccal and mesiolingual root canals were randomly prepared with either mentioned instruments. Pre- and post-instrumentation CBCT images were taken and the thickness of canal walls was measured in 1.5- and 3-mm distances from the furcation area. Data were analyzed using the one-way ANOVA. Tukey's post hoc tests were used for two-by-two comparisons.
  
  
  RESULTS
  At 1.5-mm distance, there was no significant difference between different instruments. However, at 3-mm distances, Gates-Glidden drills removed significantly more dentin compared to FlexMaster files (mean=0.18 mm) (P<0.02); however, two-by-two comparisons did not reveal any significant differences between the other groups.
  
  
  CONCLUSIONS
  All tested instruments can be effectively used in clinical settings for coronal pre-enlargement.
authors.affiliation: Endodontist, Private Practic , Babol, Iran;
authors.forename: Amin
authors.initials: A
authors.lastname: Homayoon
authors.affiliation: Department of Endodontics, Dental School, Babol University of Medical Sciences, Babol, Iran;
authors.forename: Mahmood Reza
authors.initials: MR
authors.lastname: Hamidi
authors.affiliation: Department of Endodontics, Dental school, Mazandaran University of Medical Sciences, Sari, Iran;
authors.forename: Azam
authors.initials: A
authors.lastname: Haddadi
authors.affiliation: Department of Endodontics, Dental School, Babol University of Medical Sciences, Babol, Iran;
authors.forename: Zahra Sadat
authors.initials: ZS
authors.lastname: Madani
authors.affiliation: Department of Oral and Maxillofacial Radiology, Dental School, Babol University of Medical Sciences, Babol, Iran;
authors.forename: Ehsan
authors.initials: E
authors.lastname: Moudi
authors.affiliation: Non-Communicable Pediatric Diseases Research Center, Babol University of Medical Sciences, Babol, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Bijani
keywords: Cone-Beam Computed Tomography; Coronal Flaring; Coronal Pre-Enlargement; Root Canal Preparation; Root Canal Treatment