title: Molecular microbiological evaluation of passive ultrasonic activation as a supplementary disinfecting step: a clinical study.
abstract: BACKGROUND
  This in vivo study used molecular microbiology methods to evaluate the effects of passive ultrasonic irrigation (PUI) as a supplementary disinfecting step after root canal preparation.
  
  
  METHODS
  Samples were taken from 10 necrotic root canals of teeth with apical periodontitis before (S1) and after rotary nickel-titanium instrumentation using 2.5% NaOCl as the irrigant (S2) and then after PUI for NaOCl activation (S3). The parameters examined included the incidence of positive broad-range polymerase chain reaction (PCR) results for bacterial presence, the impact on bacterial diversity evaluated by PCR-denaturing gradient gel electrophoresis (DGGE), the quantitative bacterial reduction determined by real-time PCR, and the identification of persistent species by clone library analysis.
  
  
  RESULTS
  All S1 samples were positive for bacteria in all tests. Treatment procedures were significantly effective in reducing the incidence of positive results for bacteria, the number of bacterial cells (infectious bioburden), and the bacterial diversity (number of species and abundance). However, the supplementary PUI approach did not succeed in significantly enhancing disinfection beyond that achieved by chemomechanical preparation. Several bacterial species/phylotypes were identified in post-treatment samples that were positive for bacteria.
  
  
  CONCLUSIONS
  Findings from this clinical study including a small sample size suggest that PUI can be ineffective in significantly improving disinfection of the main root canal after chemomechanical procedures.
authors: Institute of Microbiology Professor Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors: Simone S M
authors: SS
authors: Paiva
authors: José F
authors: JF
authors: Siqueira
authors: Isabela N
authors: IN
authors: Rôças
authors: Flávia L
authors: FL
authors: Carmo
authors: Deborah C A
authors: DC
authors: Leite
authors: Dennis C
authors: DC
authors: Ferreira
authors: Caio T C
authors: CT
authors: Rachid
authors: Alexandre S
authors: AS
authors: Rosado
mesh_terms: D039903:Actinobacteria / Q000187:drug effects / Q000302:isolation & purification; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D058491:Bacterial Load / Q000187:drug effects; D002167:Campylobacter / Q000187:drug effects / Q000302:isolation & purification; D003722:Dental Alloys / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000382:microbiology*; D003790:Dental Pulp Necrosis / Q000382:microbiology / Q000628:therapy; D004586:Electrophoresis / Q000379:methods; D016967:Fusobacterium nucleatum / Q000187:drug effects / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D009532:Nickel / Q000737:chemistry; D010485:Periapical Periodontitis / Q000382:microbiology / Q000628:therapy; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000302:isolation & purification; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D016369:Smear Layer; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013010:Sonication / Q000295:instrumentation / Q000379:methods*; D007507:Therapeutic Irrigation / Q000295:instrumentation / Q000379:methods; D014025:Titanium / Q000737:chemistry; D014465:Ultrasonics / Q000295:instrumentation
chemical_list: D003722:Dental Alloys; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012388:Root Canal Irrigants; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium; D012973:Sodium Hypochlorite