title: Clinical Antibacterial Effectiveness of Root Canal Preparation with Reciprocating Single-instrument or Continuously Rotating Multi-instrument Systems.
abstract: BACKGROUND
  This in vivo study compared the antibacterial effectiveness of a reciprocating single-instrument system (Reciproc; VDW, Munich, Germany) and a rotary multi-instrument system (BioRaCe; FKG Dentaire, La Chaux-de-Fonds, Switzerland) during the preparation of infected root canals of teeth with primary apical periodontitis.
  
  
  METHODS
  Root canals from single-rooted teeth with necrotic pulps and apical periodontitis were instrumented using either Reciproc (n = 29) or BioRaCe (n = 30) instruments under irrigation with 2.5% sodium hypochlorite. DNA was extracted from samples taken before and after preparation and subjected to quantitative analysis of total bacteria and streptococci by using the quantitative real-time polymerase chain reaction.
  
  
  RESULTS
  All initial samples were positive for the presence of bacteria, with median numbers of 7.1 × 10(5) and 1.31 × 10(5) bacterial cells for the Reciproc and BioRaCe groups, respectively. After preparation with Reciproc and BioRaCe, 16 (55%) and 15 (50%) root canals still had detectable bacteria with median counts of 7.05 × 10(2) and 6.03 × 10(1), respectively. Both systems were highly effective in reducing the total bacterial counts (P < .001), and there were no significant differences between them (P > .05). Streptococci were highly frequent, and both systems succeeded in significantly reducing their levels (P < .001).
  
  
  CONCLUSIONS
  Both reciprocating single-instrument and rotary multi-instrument systems were highly effective in reducing the counts of total bacteria and streptococci in root canals of teeth with apical periodontitis. Regardless of the system used, approximately one half of the teeth still had detectable bacteria.
authors.affiliation: Department of Endodontics and Molecular Microbiology Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Mônica A S
authors.initials: MA
authors.lastname: Neves
authors.affiliation: Department of Endodontics and Molecular Microbiology Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: José C
authors.initials: JC
authors.lastname: Provenzano
authors.affiliation: Department of Endodontics and Molecular Microbiology Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Isabela N
authors.initials: IN
authors.lastname: Rôças
authors.affiliation: Department of Endodontics and Molecular Microbiology Laboratory, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: jf_siqueira@yahoo.com.
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058491:Bacterial Load; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003790:Dental Pulp Necrosis / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000382:microbiology*; D018915:Root Canal Preparation / Q000295:instrumentation*; D013291:Streptococcus / Q000302:isolation & purification; D055815:Young Adult
keywords: Apical periodontitis; bacterial reduction; endodontic treatment; molecular microbiology; single-file instrumentation