title: [Clinical evaluation of nickel-titanium rotary instruments Hero 642 in root canal preparation].
abstract: OBJECTIVE
  This research is aimed to assess the clinical value of the Nickel-titanium (NiTi) rotary instruments Hero 642 in root canal preparation.
  
  
  METHODS
  60 molars were instrumented by Hero 642 rotary instruments using crown-down technique in the experimental group, and by K files using step-back technique in the control group. All teeth were obturated with lateral condensation method. The efficiency of preparation and obturation was analyzed by radiographs before and after treatment. The canal curvature and operation time were compared by means of Student's t test, and the incidence of complications and post-treatment pain were compared by means of Chi square test between two groups.
  
  
  RESULTS
  No transportation, apical blockage, ledge or perforation was found in the experimental group. The Hero 642 instruments could keep the original curvature and flow of the root canals. There was more canal complications in the control group than in the experimental group (P<0.005). The operative time was shorter and post treatment pain seldom occurred in the experimental group.
  
  
  CONCLUSIONS
  The NiTi rotary instruments Hero 642 can be used for preparation of root canals effectively and safely, and is worth wide application.
authors.affiliation: Department of Endodontics, Guanghua College of Stomatology, Sun Yat-sen University. Guangzhou 510055, Guangdong Province, China. xuqionggz@yahoo.com.cn
authors.forename: Qiong
authors.initials: Q
authors.lastname: Xu
authors.forename: Jun-Qi
authors.initials: JQ
authors.lastname: Lin
authors.forename: Han
authors.initials: H
authors.lastname: Chen
authors.forename: Xi
authors.initials: X
authors.lastname: Wei
mesh_terms: D006801:Humans; D008963:Molar; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D014025:Titanium
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium