title: Bacterial reduction with nickel-titanium rotary instrumentation.
abstract: The purpose of this study was to compare intracanal bacterial reduction on teeth instrumented with 0.04 tapered nickel-titanium (NiTi) rotary instrumentation to bacterial reduction when using a stainless-steel K-file step-back technique using sterile saline irrigation. Forty-eight patients with apical periodontitis were randomly assigned treatment type. The canals were sampled before, during, and after instrumentation. The samples were incubated anaerobically for 7 days at 37 degrees C, colony-forming unit numbers calculated, and a log transformation performed to normalize the counts. Teeth exhibiting apical periodontitis were uniformly infected, whereas vital control teeth were not. A similar and uniform reduction occurred with progressive filing, regardless of technique (p < 0.0001). There was no detectable difference in colony-forming unit count after NiTi rotary or stainless-steel hand instrumentation (p = 0.42). Neither technique could predictably render canals free of bacteria. The results of this study indicate NiTi rotary and stainless-steel hand K-file step-back instrumentation techniques were not significantly different in their ability to reduce intracanal bacteria.
authors.affiliation: Department of Orthodontics, University of North Carolina School of Dentistry, Chapel Hill 27599, USA.
authors.forename: B C
authors.initials: BC
authors.lastname: Dalton
authors.forename: D
authors.initials: D
authors.lastname: Orstavik
authors.forename: C
authors.initials: C
authors.lastname: Phillips
authors.forename: M
authors.initials: M
authors.lastname: Pettiette
authors.forename: M
authors.initials: M
authors.lastname: Trope
mesh_terms: D000704:Analysis of Variance; D001419:Bacteria / Q000302:isolation & purification; D015169:Colony Count, Microbial; D003755:Dental High-Speed Technique; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000382:microbiology*; D004867:Equipment Design; D006801:Humans; D009532:Nickel; D010485:Periapical Periodontitis / Q000382:microbiology; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D013193:Stainless Steel; D014025:Titanium
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium