title: Dentinal damage and fracture resistance of oval roots prepared with single-file systems using different kinematics.
abstract: BACKGROUND
  Vertical root fracture is a common finding in endodontically treated teeth, notably oval roots. The aim of the present study was to determine the effect of instrumentation kinematics and the material of instrument construction of single-file systems on dentin walls and fracture resistance of oval roots.
  
  
  METHODS
  Sixty-five roots with oval canals were allocated into a control group (n = 5) and 3 experimental groups of 20 roots each. Group WO was instrumented with the WaveOne primary file (Dentsply Maillefer, Baillagues, Switzerland), group PT-Rec was prepared with F2 ProTaper files (Dentsply Maillefer, Baillagues, Switzerland) used in a reciprocating motion, and group PT-Rot was prepared with F2 ProTaper files used in a rotation motion. For crack evaluation, half of the samples (n = 30) were embedded in acrylic resin, and the blocks were sectioned at 3, 6, and 9 mm from the apex. The sections were examined under a stereomicroscope and scored for crack presence. The other half of the specimens (n = 30) were obturated using lateral condensation of gutta-percha and AdSeal sealer (Meta Biomed Co, Ltd, Chungbuk, Korea). The specimens were then subjected to a load of 1 mm/min to determine the force required to fracture the roots.
  
  
  RESULTS
  WaveOne instruments induced the least amount of cracks and exhibited greatest resistance to fracture compared with ProTaper F2 files whether used in reciprocating or rotating motions.
  
  
  CONCLUSIONS
  The alloy from which the material is manufactured is a more important factor determining the dentin damaging potential of single-file instruments than the motion of instrumentation.
authors.affiliation: Department of Endodontics, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt. Electronic address: Hend.abouelnasr@dentistry.cu.edu.eg.
authors.forename: Hend Mahmoud
authors.initials: HM
authors.lastname: Abou El Nasr
authors.affiliation: Department of Endodontics, Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt.
authors.forename: Karim Galal
authors.initials: KG
authors.lastname: Abd El Kader
mesh_terms: D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000293:injuries* / Q000473:pathology; D003804:Dentin / Q000293:injuries* / Q000473:pathology; D004853:Epoxy Resins / Q000627:therapeutic use; D004867:Equipment Design; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D009038:Motion; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012399:Rotation; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013314:Stress, Mechanical; D019227:Tooth Apex / Q000293:injuries; D014082:Tooth Fractures / Q000503:physiopathology*; D014092:Tooth Root / Q000293:injuries* / Q000473:pathology; D019553:Tooth, Nonvital / Q000503:physiopathology; D019415:Torque
chemical_list: D003722:Dental Alloys; D004853:Epoxy Resins; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; C534916:epoxy resin-based root canal sealer; D006171:Gutta-Percha; D012973:Sodium Hypochlorite
keywords: Crack; M-Wire; ProTaper; WaveOne; oval canals; reciprocation; root fracture