title: A new bacterial species associated with failed endodontic treatment: identification and description of Actinomyces radicidentis.
abstract: OBJECTIVE
  This report describes 2 endodontic patients who had persistent signs and symptoms after conventional root canal treatment. The aim of this study was to determine what microorganisms were present in the root canals of the teeth with failed endodontic therapy.
  
  
  METHODS
  After removal of the root fillings, the canals were sampled by advanced microbiological techniques and the isolates were characterized by various tests.
  
  
  RESULTS
  Bacteria, which grew in pure cultures, were isolated in each case. The bacteria were similar to each other and were classified as Actinomyces on the basis of phylogenic and phenotypic evidence. The bacteria were different from others within the genus, thus warranting designation as a new species, Actinomyces radicidentis.
  
  
  CONCLUSIONS
  The 2 cases of endodontic failure were infected with A radicidentis, a new Actinomyces species. This bacterium joins a restricted group of other microorganisms that have been associated with failure of root canal treatment.
authors.affiliation: Department of Oral Microbiology, Umeå University, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Kalfas
authors.forename: D
authors.initials: D
authors.lastname: Figdor
authors.forename: G
authors.initials: G
authors.lastname: Sundqvist
mesh_terms: D000190:Actinomyces / Q000145:classification* / Q000187:drug effects; D000196:Actinomycosis / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use; D002126:Calcium Hydroxide / Q000627:therapeutic use; D003786:Dental Pulp Cavity / Q000382:microbiology*; D004352:Drug Resistance, Microbial; D005260:Female; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D010482:Periapical Abscess / Q000382:microbiology; D010483:Periapical Diseases / Q000382:microbiology*; D010484:Periapical Granuloma / Q000382:microbiology; D010485:Periapical Periodontitis / Q000382:microbiology; D010641:Phenotype; D010802:Phylogeny; D012388:Root Canal Irrigants / Q000627:therapeutic use; D012390:Root Canal Therapy; D012391:Root Resorption / Q000382:microbiology; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D017211:Treatment Failure
chemical_list: D000891:Anti-Infective Agents, Local; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite; D002126:Calcium Hydroxide