title: Effect of ProTaper Universal, Endoflare, Revo-S, HyFlex coronal flaring instruments, and Gates Glidden drills on crack formation.
abstract: BACKGROUND
  The aim of the present study was to evaluate crack formation after flaring root canals with Gates Glidden drills and ProTaper Universal (SX; Dentsply Maillefer, Ballaigues, Switzerland), Endoflare (MicroMega, Besançon, France), Revo-S (MicroMega), and HyFlex (Coltene-Whaledent, Allstetten, Switzerland) flaring instruments.
  
  
  METHODS
  One-hundred eight mandibular molars were selected. Eighteen teeth were left unprepared to serve as negative controls; the experimental groups consisted of the mesiobuccal and mesiolingual root canals of the remaining 90 teeth, which were instrumented with the following coronal flaring instruments: Gates Glidden drills and ProTaper Universal SX, Endoflare, Revo-S SC1, and HyFlex 25.08 instruments. All roots were then sectioned perpendicular to the long axis at 1, 2, 3, 4, 6, and 8 mm from the cementoenamel junction. The sections were inspected under a stereomicroscope, and any crack formations were recorded. The data were analyzed using the chi-square test (P = .05).
  
  
  RESULTS
  The Gates Glidden drills resulted in a higher rate of crack formation than that noted in the control group (P < .05). Flaring of the root canals using the ProTaper Universal, Endoflare, Revo-S, and HyFlex instruments resulted in crack formation similar to that of the control group (P > .05).
  
  
  CONCLUSIONS
  The use of the Gates Glidden drills resulted in the formation of the most cracks. However, the results for the ProTaper Universal, Endoflare, Revo-S, and HyFlex flaring instruments were similar to those of the control group in terms of crack formation.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey. Electronic address: dt_hakan82@hotmail.com.
authors.forename: Hakan
authors.initials: H
authors.lastname: Arslan
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: Ertuğrul
authors.initials: E
authors.lastname: Karataş
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Katip Çelebi University, İzmir, Turkey.
authors.forename: Ismail Davut
authors.initials: ID
authors.lastname: Capar
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: Damla
authors.initials: D
authors.lastname: Ozsu
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
authors.forename: Ezgi
authors.initials: E
authors.lastname: Doğanay
mesh_terms: D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000293:injuries*; D003804:Dentin / Q000293:injuries*; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D008963:Molar / Q000293:injuries; D009532:Nickel / Q000737:chemistry; D012388:Root Canal Irrigants / Q000008:administration & dosage; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D012973:Sodium Hypochlorite / Q000008:administration & dosage; D014025:Titanium / Q000737:chemistry; D019415:Torque
chemical_list: D003722:Dental Alloys; D012388:Root Canal Irrigants; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite
keywords: Coronal flaring; Endoflare; Gates Glidden; HyFlex; ProTaper Universal; Revo-S; cracks; dentinal damage