title: WaveOne Rotary Instruments after Clinical Use.
abstract: BACKGROUND
  The purpose of this study was to evaluate the incidence and mode of WaveOne (Dentsply Tulsa Dental Specialties, Tulsa, OK) instrument defects after single use at different endodontic clinics.
  
  
  METHODS
  A total of 438 WaveOne instruments were collected after clinical use from the 4 specialist clinics over a 12-month period and from 1 graduate program over a 20-month period. The incidence and type of instrument defects were analyzed. The lateral surfaces of part of the defective instruments and fracture surfaces of fractured files were examined using scanning electron microscopy. Unused and clinically used files were examined by a nanoindentation test.
  
  
  RESULTS
  Of the 438 WaveOne instruments collected, 42 (9.6%) had defects: 40 (9.1%) were distorted and 2 (0.5%) files had fractured, 1 Small and 1 Primary file. Clear differences in the frequency of defects were found among the 3 file sizes; the occurrence of distortion and fracture were highest with the Small file (21.2% and 0.7%, respectively) followed by the Primary file (4.4% and 0.4%, respectively) (P < .05). No defects were detected on the Large file. The cause of the 2 fractures was shear stress. Instruments from various clinics showed no significantly different occurrence of instrument deformation. Unwinding occurred at 1.2-3.1 mm from the tip. No significant difference in nanohardness was detected among unused and used instruments.
  
  
  CONCLUSIONS
  The risk of WaveOne fracture is very low when files are singly used by endodontists and residents. Unwinding of the files occurred most frequently in the Small file. The frequency of defects of WaveOne instruments were not influenced by the operator.
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada; Department of Materials Engineering, Faculty of Applied Science, The University of British Columbia, Vancouver, Canada.
authors.forename: Ya
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Coil
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
authors.forename: Anthony John
authors.initials: AJ
authors.lastname: Mo
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
authors.forename: Zhejun
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Hieawy
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada; Department of Stomatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry, The University of British Columbia, Vancouver, Canada. Electronic address: markush@dentistry.ubc.ca.
authors.forename: Markus
authors.initials: M
authors.lastname: Haapasalo
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D015994:Incidence; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D014025:Titanium / Q000737:chemistry*
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Clinical use; WaveOne; fracture; nickel-titanium instrument; operator; shear failure