title: Root canal shaping with manual stainless steel files and rotary Ni-Ti files performed by students.
abstract: OBJECTIVE
  To investigate root canal shaping with manual stainless steel files and rotary Ni-Ti files by students.
  
  
  METHODS
  Two hundred and ten simulated root canals with the same geometrical shape and size in acrylic resin blocks were prepared by 21 undergraduate dental students with manual stainless steel files using a stepback technique or with rotary Ni-Ti files in crown-down technique. Preparation length, canal shape, incidence of fracture and preparation time were investigated.
  
  
  RESULTS
  Zips and elbows occurred significantly (P < 0.001) less frequently with rotary than with manual preparation. The correct preparation length was achieved significantly (P < 0.05) more often with rotary Ni-Ti files than with manual stainless steel files. Fractures occurred significantly (P < 0.05) less frequently with hand instrumentation. The mean time required for manual preparation was significantly (P < 0.001) longer than that required for rotary preparation. Prior experience with a hand preparation technique was not reflected in an improved quality of the subsequent engine-driven preparation.
  
  
  CONCLUSIONS
  Inexperienced operators achieved better canal preparations with rotary Ni-Ti instruments than with manual stainless steel files. However, rotary preparation was associated with significantly more fractures.
authors.affiliation: Department of Operative Dentistry, Philipps University, Marburg, Germany. sonntag@mailer.uni-marburg.de
authors.forename: D
authors.initials: D
authors.lastname: Sonntag
authors.forename: A
authors.initials: A
authors.lastname: Guntermann
authors.forename: S K
authors.initials: SK
authors.lastname: Kim
authors.forename: V
authors.initials: V
authors.lastname: Stachniss
mesh_terms: D016009:Chi-Square Distribution; D002983:Clinical Competence; D018592:Cross-Over Studies; D003722:Dental Alloys; D003762:Dental Instruments; D004708:Endodontics / Q000193:education*; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation*; D013193:Stainless Steel; D018709:Statistics, Nonparametric; D013335:Students, Dental; D013647:Task Performance and Analysis; D014025:Titanium; D019227:Tooth Apex
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium