title: Bacterial reduction by extensive versus conservative root canal instrumentation in vitro.
abstract: OBJECTIVE
  This study aimed to test the hypothesis that aggressive dentin removal through greater-tapered instrumentation reduces the intracanal bacteria more effectively than conservative dimension instrumentation.
  
  
  METHODS
  Twenty extracted human lower premolar teeth were used. After extirpation of the pulps, the teeth were autoclaved and immersed in a broth inoculated with Enterococcus faecalis and incubated for 7 days to allow infection of the dentinal tubules. The teeth were divided into 2 experimental groups, each comprising 10 teeth. The teeth were instrumented either with ProTaper or with Hero Shaper nickel-titanium rotary instrumentation techniques. It was calculated that ProTaper theoretically has the potential to remove at least twice the dentin volume compared with Hero Shaper. The apical preparation was standardized to file size 30. Saline solution was used for irrigation. Bacteriological samples were taken before and after instrumentation and plated onto tryptic soy agar, and the reduction in numbers was calculated.
  
  
  RESULTS
  Both instrumentation techniques significantly reduced the number of bacteria in the root canal (p<0.05). Reduction in absolute bacterial numbers was up to 98%. There was no statistically significant difference between the two techniques.
  
  
  CONCLUSIONS
  Preparation with an instrumentation technique removing substantial amounts of dentin did not reduce the intracanal bacteria more effectively than a more conservative instrumentation technique.
authors.affiliation: Department of Endodontics and Conservative Treatment, Gülhane Military Medical Academy, Center for Dental Sciences, Ankara, Turkey. cumhuraydin@gata.edu.tr
authors.forename: Cumhur
authors.initials: C
authors.lastname: Aydin
authors.forename: Yasar Meric
authors.initials: YM
authors.lastname: Tunca
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Senses
authors.forename: Mehmet
authors.initials: M
authors.lastname: Baysallar
authors.forename: Guven
authors.initials: G
authors.lastname: Kayaoglu
authors.forename: Dag
authors.initials: D
authors.lastname: Ørstavik
mesh_terms: D001641:Bicuspid; D015169:Colony Count, Microbial; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology; D013293:Enterococcus faecalis / Q000302:isolation & purification; D006801:Humans; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D018709:Statistics, Nonparametric