title: Root-canal shaping with manual and rotary Ni-Ti files performed by students.
abstract: OBJECTIVE
  To investigate root-canal shaping with manual and rotary Ni-Ti files performed by students.
  
  
  METHODS
  Thirty undergraduate dental students prepared 150 simulated curved root canals in resin blocks with manual Ni-Ti files with a stepback technique and 450 simulated curved canals with rotary Ni-Ti files with a crowndown technique. Incidence of fracture, preparation length, canal shape and preparation time were investigated. Questionnaires were then issued to the students for them to note their experience of the two preparation methods.
  
  
  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 files than with manual files. Instrument fractures were recorded in only 1.3% of cases with both rotary and manual preparation. 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 rotary preparation. Approximately 83% of the students claimed to have a greater sense of security in rotary than in manual preparation. Overall 50% felt that manual and engine-driven preparation should be given equal status in undergraduate dental education.
  
  
  CONCLUSIONS
  Inexperienced operators achieved better canal preparations with rotary instruments than with manual files. No difference in fracture rate was recorded between the two systems.
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: S
authors.initials: S
authors.lastname: Delschen
authors.forename: V
authors.initials: V
authors.lastname: Stachniss
mesh_terms: D001290:Attitude; D003258:Consumer Behavior; D003722:Dental Alloys; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D004497:Education, Dental; D004708:Endodontics / Q000193:education; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D009532:Nickel; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D018709:Statistics, Nonparametric; D013335:Students, Dental / Q000523:psychology; D011795:Surveys and Questionnaires; D013997:Time Factors; D014025:Titanium
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium