title: Extended apical enlargement with hand files versus rotary NiTi files. Part II.
abstract: OBJECTIVE
  The objective of this study was to compare 2 preparation techniques performed under simulated clinical conditions with extended apical enlargement following determination of the optimal apical preparation size (APS).
  
  
  METHODS
  After preflaring 240 root canals, APS was evaluated as outlined in Part I. The apical portion was shaped to APS either with rotary NiTi Lightspeed instruments (LS) or NiTi hand instruments (HA) using the balanced force technique in a phantom head. After sectioning the apical area at 3 levels, every cross section was analyzed microscopically for circumferential removal of canal wall dentine. Loss of working length, instrument separation, and perforation were additionally recorded.
  
  
  RESULTS
  In 70% (LS) and 69% (HA) of the root canals, 2 of 3 levels demonstrated that the root canal dentin was cut circumferentially. Neither loss of working length nor perforation occurred in both groups. Four LS instruments separated.
  
  
  CONCLUSIONS
  APS frequently results in a nearly complete apical preparation regardless of the preparation techniques. In a few cases apical enlargement to APS does not achieve complete cutting of the canal walls. There was a rather slight risk of serious procedural errors.
authors.affiliation: Department of Conservative Dentistry, University of Szeged, Szeged, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Bartha
authors.forename: Matthias
authors.initials: M
authors.lastname: Kalwitzki
authors.forename: Claus
authors.initials: C
authors.lastname: Löst
authors.forename: Roland
authors.initials: R
authors.lastname: Weiger
mesh_terms: D000465:Algorithms; D003722:Dental Alloys; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D004867:Equipment Design; D006801:Humans; D008963:Molar / Q000033:anatomy & histology; D009532:Nickel; D015588:Observer Variation; D009811:Odontometry; D012016:Reference Values; D018915:Root Canal Preparation / Q000295:instrumentation*; D014025:Titanium; D019227:Tooth Apex / Q000033:anatomy & histology*
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium