title: Persistent extraradicular infection in root-filled asymptomatic human tooth: scanning electron microscopic analysis and microbial investigation after apical microsurgery.
abstract: BACKGROUND
  Procedural accidents have a negative effect on healing and might contribute to the persistence of infections in inaccessible apical areas, requiring surgical intervention. This report describes a case of persistent apical periodontitis of a lower left first molar associated with the sinus tract and a periapical lesion that required nonsurgical endodontic retreatment and apical surgery for resolution.
  
  
  METHODS
  The tooth had received endodontic treatment 3 years ago and had to be retreated using the crown-down technique with chemical auxiliary substance (2% chlorhexidine gel), foramen patency, and enlargement and was filled in a single appointment. The occlusal access cavity was immediately restored with composite resin. After 1 month, it could be observed that the sinus tract persisted and, radiographically, the lesion remained unaltered. Therefore, endodontic microsurgery was indicated. Apical microsurgery was performed under magnification with the use of a dental operating microscope including apicectomy, root end with ultrasound, and sealing with mineral trioxide aggregate. A microbiological sample was collected from the apical lesion. The resected distal root apex was observed by scanning electron microscopy.
  
  
  RESULTS
  The following species were detected: Actinomyces naeslundii and Actinomyces meyeri, Propionibacterium propionicum, Clostridium botullinum, Parvimonas micra, and Bacteroides ureolyticus; scanning electron microscopic analysis revealed bacterial biofilm surrounding the apical foramen and external radicular surface. Gutta-percha overfilling at the apex because of a zip caused during initial endodontic treatment could be observed. A 6-month follow-up showed apparent radiographic periapical healing, which progressed after 24 months.
  
  
  CONCLUSIONS
  Gram-positive anaerobic bacteria and extraradicular biofilm seem to participate in the maintenance of persistent periapical pathology, and endodontic retreatment followed by periapical microsurgery proved to be a successful alternative in the resolution of persistent extraradicular infections.
authors.affiliation: Department of Restorative Dentistry, Endodontic Area, Piracicaba Dental School, State University of Campinas, Campinas, Brazil.
authors.forename: Fernanda G C
authors.initials: FG
authors.lastname: Signoretti
authors.forename: Marcos S
authors.initials: MS
authors.lastname: Endo
authors.forename: Brenda P F A
authors.initials: BP
authors.lastname: Gomes
authors.forename: Francisco
authors.initials: F
authors.lastname: Montagner
authors.forename: Fernanda B
authors.initials: FB
authors.lastname: Tosello
authors.forename: Rogério C
authors.initials: RC
authors.lastname: Jacinto
mesh_terms: D000190:Actinomyces / Q000302:isolation & purification; D000328:Adult; D017607:Aluminum Compounds / Q000627:therapeutic use; D001047:Apicoectomy / Q000379:methods*; D058070:Asymptomatic Diseases; D001439:Bacteroides / Q000302:isolation & purification; D018441:Biofilms; D017610:Calcium Compounds / Q000627:therapeutic use; D003014:Clostridium botulinum / Q000302:isolation & purification; D003751:Dental Fistula / Q000628:therapy; D004338:Drug Combinations; D005260:Female; D005500:Follow-Up Studies; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008866:Microsurgery / Q000379:methods; D010087:Oxides / Q000627:therapeutic use; D010462:Peptostreptococcus / Q000302:isolation & purification; D010485:Periapical Periodontitis / Q000382:microbiology* / Q000601:surgery; D059745:Piezosurgery / Q000379:methods; D011424:Propionibacterium / Q000302:isolation & purification; D019233:Retreatment; D012184:Retrograde Obturation / Q000379:methods; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000379:methods; D017640:Silicates / Q000627:therapeutic use; D019227:Tooth Apex / Q000382:microbiology / Q000473:pathology; D019553:Tooth, Nonvital / Q000628:therapy*
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate