title: Comparative assessment of the effects of Gates-Glidden, Largo, LA-Axxess, and New Brazilian Drill CPdrill on coronal pre-enlargement: cone-beam computed tomographic analysis.
abstract: BACKGROUND
  The removal of dentin interferences from the cervical third of root canals is essential for their correct cleaning and shaping and to facilitate access of endodontic instruments to the critical apical region. In mandibular molars, the concavity observed in the furcation area reduces dentin thickness, making this region more susceptible to perforation. The present ex vivo study used cone-beam computed tomographic imaging to compare 3 rotary burs with a new rotary bur recently launched in Brazil (ie, CPdrill; Helse Industry and Commerce Ltda, Santa Rosa, São Paulo, Brazil) regarding the amount of dentin removal from the distal wall of the mesial root of mandibular first molars.
  
  
  METHODS
  A total of 40 root canals were selected and randomly divided into 4 groups for cervical preparation: Gates-Glidden burs #2 and #3 (Dentsply Maillefer, Ballaigues, Switzerland), Largo burs #1 and #2 (Dentsply Maillefer), LA-Axxess burs #1 and #2 (SybronEndo, Glendora, CA), and CPdrill burs (1-size only). Dentin thickness in the distal wall of mesial canals at 2 mm from the furcation was measured using I-CATvision software before and after cervical preparation.
  
  
  RESULTS
  There was no statistically significant difference between groups regarding residual dentin thickness after instrumentation with the drills (P = .684).
  
  
  CONCLUSIONS
  It was concluded that CPdrill is safe for use in cervical preparation of the mesial root of mandibular first molars because it did not promote excessive dentin removal on distal walls.
authors.affiliation: Public Practice, Santa Maria, Rio Grande do Sul, Brazil. Electronic address: cbfendo@gmail.com.
authors.forename: Cláudia Bohrer
authors.initials: CB
authors.lastname: Flores
authors.affiliation: Endodontic Division, Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Rio Grande do Sul, Brazil.
authors.forename: Francisco
authors.initials: F
authors.lastname: Montagner
authors.affiliation: Endodontic Division, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Brenda P F A
authors.initials: BP
authors.lastname: Gomes
authors.affiliation: Radiology Division, Department of Stomatology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
authors.forename: Gustavo Nogara
authors.initials: GN
authors.lastname: Dotto
authors.affiliation: Endodontic Division, Department of Stomatology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
authors.forename: Marcia
authors.initials: M
authors.lastname: da Silva Schmitz
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D003804:Dentin / Q000000981:diagnostic imaging*; D004867:Equipment Design; D006801:Humans; D008963:Molar / Q000000981:diagnostic imaging; D009811:Odontometry / Q000379:methods; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D019237:Tooth Cervix / Q000000981:diagnostic imaging
chemical_list: D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite
keywords: Cervical preparation; cone-beam computed tomography; mandibular first molars; risk zone; rotary burs