title: [Clinical study on effects of root canal instrumentation on the root canal microflora].
abstract: OBJECTIVE
  To investigate the effects of instrumentation and ultrasonic treatment on the root canal flora.
  
  
  METHODS
  A total of 21 single-rooted teeth with chronic apical periodontitis were selected and prepared using step-back/ultrasonic technique, Samples were taken before and after the step-back preparation, and after the ultrasonic treatment.
  
  
  RESULTS
  The number and species of bacteria in the root canal were both reduced dramatically and there were significant differences among the three groups (P < 0.05).
  
  
  CONCLUSIONS
  The instrumentation and ultrasonic treatment of root canal can effectively reduce the number and species of root canal microflora.
authors.affiliation: School of Stomatology, Hubei Medical University.
authors.forename: J
authors.initials: J
authors.lastname: He
authors.forename: Z
authors.initials: Z
authors.lastname: Bian
authors.forename: B
authors.initials: B
authors.lastname: Fan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003762:Dental Instruments / Q000382:microbiology*; D003786:Dental Pulp Cavity / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000382:microbiology*; D018915:Root Canal Preparation / Q000295:instrumentation*; D014464:Ultrasonic Therapy / Q000379:methods