title: Disinfecting oval-shaped root canals: effectiveness of different supplementary approaches.
abstract: BACKGROUND
  This study compared the ability of different approaches to supplement the antibacterial effects of chemomechanical preparation in oval-shaped root canals.
  
  
  METHODS
  Long oval canals from extracted teeth infected with Enterococcus faecalis (ATCC 29212) were chemomechanically prepared up to a 40/04 rotary BioRaCe instrument using 2.5% NaOCl irrigation and then subjected to two supplementary protocols. In the passive ultrasonic irrigation (PUI)/chlorhexidine (CHX) group, canals were subjected to PUI for the activation of NaOCl followed by a final rinse with 0.2% CHX digluconate solution. In the Hedström group, canals received additional Hedström filing directed towards the buccal and lingual canal recesses. Bacteriological samples were taken before and after preparation, after PUI or Hedström instrumentation, and after CHX final rinsing.
  
  
  RESULTS
  Chemomechanical preparation and the supplementary steps promoted a highly significant bacterial reduction (P < .001). Quantitative (reduction in levels) and qualitative (frequency of negative cultures) analyses showed that PUI alone or Hedström filing did not significantly increase bacterial reduction (P > .05). Further rinsing with CHX also failed to significantly increase bacterial elimination when compared with post-PUI samples. However, the cumulative antibacterial effects of PUI and CHX final rinse were effective in significantly reducing bacterial counts to levels below those achieved after preparation (P = .03). This combined PUI/CHX approach also resulted in a significant increase in the incidence of negative cultures (P = .04).
  
  
  CONCLUSIONS
  Findings suggest that there may be a benefit of using the PUI for the activation of NaOCl followed by a final rinse with CHX as supplementary steps in the treatment of infected oval-shaped root canals.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Flávio R F
authors.initials: FR
authors.lastname: Alves
authors.forename: Bernardo M
authors.initials: BM
authors.lastname: Almeida
authors.forename: Mônica A S
authors.initials: MA
authors.lastname: Neves
authors.forename: Jaime O
authors.initials: JO
authors.lastname: Moreno
authors.forename: Isabela N
authors.initials: IN
authors.lastname: Rôças
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
mesh_terms: D000891:Anti-Infective Agents, Local / Q000627:therapeutic use; D058491:Bacterial Load; D018441:Biofilms / Q000187:drug effects; D002614:Chelating Agents / Q000627:therapeutic use; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000382:microbiology*; D004203:Disinfection / Q000379:methods*; D004492:Edetic Acid / Q000627:therapeutic use; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000254:growth & development; D004867:Equipment Design; D006801:Humans; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D007507:Therapeutic Irrigation / Q000379:methods; D014465:Ultrasonics / Q000295:instrumentation
chemical_list: D000891:Anti-Infective Agents, Local; D002614:Chelating Agents; D012388:Root Canal Irrigants; D004492:Edetic Acid; D012973:Sodium Hypochlorite; C010882:chlorhexidine gluconate; D002710:Chlorhexidine