title: Root canal preparation of mandibular molars with 3 nickel-titanium rotary instruments: a micro-computed tomographic study.
abstract: BACKGROUND
  The aim of this study was to describe the canal shaping properties of ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Johnson City, TN), and WaveOne (Dentsply Maillefer) nickel-titanium instruments in mandibular first molars by using micro-computed tomographic (micro-CT) scanning.
  
  
  METHODS
  A total of 36 maxillary first molars with 2 separate mesial canals and 1 distal canal were selected and scanned preoperatively and postoperatively by using micro-CT scanning with a voxel size of 30 μm. Canals were prepared with PTU, PTN, and WaveOne systems under hypochlorite irrigation. The volume of the untreated canal; the volume of dentin removed after preparation; the amount of the uninstrumented area; and the transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time and instrument failure were also recorded.
  
  
  RESULTS
  Instrumentation of canals increased their volume and surface area. The distal canals had a significantly higher proportion of unprepared surfaces than mesial canals (P < .05). The PTN system produced less transportation than the WaveOne and PTU systems in the apical third of the mesial canals (P < .05). There was no significant difference on apical transportation in distal canals among the 3 instrument systems. Instrumentation with WaveOne was significantly faster than with the other 2 instruments (P < .05).
  
  
  CONCLUSIONS
  The PTN, PTU, and WaveOne instruments shaped root canals in mandibular first molars in vitro without significant shaping errors. The curved canals prepared using PTN had less apical transportation than the canals prepared using WaveOne and PTU.
authors.affiliation: State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry; Department of Materials Engineering, The University of British Columbia, Vancouver, Canada.
authors.forename: Ya
authors.initials: Y
authors.lastname: Shen
authors.affiliation: State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China. Electronic address: phs301@vip.163.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Peng
authors.affiliation: Division of Endodontics, Department of Oral Biological and Medical Sciences, Faculty of Dentistry.
authors.forename: Markus
authors.initials: M
authors.lastname: Haapasalo
mesh_terms: D019412:Anatomy, Cross-Sectional / Q000379:methods; D003722:Dental Alloys / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D003804:Dentin / Q000033:anatomy & histology; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008963:Molar / Q000033:anatomy & histology; D009532:Nickel / Q000737:chemistry*; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D055114:X-Ray Microtomography / Q000379:methods
chemical_list: D003722:Dental Alloys; D012388:Root Canal Irrigants; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite
keywords: Micro–computed tomographic scanning; ProTaper Next; ProTaper Universal; WaveOne; nickel-titanium instrument