title: Incidence of dentinal defects after root canal preparation: reciprocating versus rotary instrumentation.
abstract: BACKGROUND
  The purpose of this study was to evaluate the incidence of dentinal defects after root canal preparation with reciprocating instruments (Reciproc and WaveOne) and rotary instruments.
  
  
  METHODS
  One hundred human central mandibular incisors were randomly assigned to 5 groups (n = 20 teeth per group). The root canals were instrumented by using the reciprocating single-file systems Reciproc and WaveOne and the full-sequence rotary Mtwo and ProTaper instruments. One group was left unprepared as control. Roots were sectioned horizontally at 3, 6, and 9 mm from the apex and evaluated under a microscope by using 25-fold magnification. The presence of dentinal defects (complete/incomplete cracks and craze lines) was noted and analyzed by using the chi-square test.
  
  
  RESULTS
  No defects were observed in the controls. All canal preparation created dentinal defects. Overall, instrumentation with Reciproc was associated with more complete cracks than the full-sequence files (P = .021). Although both reciprocating files produced more incomplete cracks apically (3 mm) compared with the rotary files (P = .001), no statistically significant differences were obtained concerning the summarized values of all cross sections (P > .05).
  
  
  CONCLUSIONS
  Under the conditions of this study, root canal preparation with both rotary and reciprocating instruments resulted in dentinal defects. At the apical level of the canals, reciprocating files produced significantly more incomplete dentinal cracks than full-sequence rotary systems (P < .05).
authors.affiliation: Central Interdisciplinary Ambulance, School of Dentistry, University of Münster, Münster, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Bürklein
authors.forename: Polymnia
authors.initials: P
authors.lastname: Tsotsis
authors.forename: Edgar
authors.initials: E
authors.lastname: Schäfer
mesh_terms: D003762:Dental Instruments / Q000009:adverse effects*; D003804:Dentin / Q000293:injuries*; D006801:Humans; D009532:Nickel; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D014025:Titanium; D018677:Tooth Injuries / Q000209:etiology
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium