title: Persistent apical periodontitis associated with a calcifying odontogenic cyst.
abstract: OBJECTIVE
  To report a case of calcifying odontogenic cyst (COC) that was suggestive of apical periodontitis adjacent to the roots of the maxillary incisor teeth.
  
  
  CONCLUSIONS
  Tooth 21 presented with clinical and radiographic signs of secondary infection, a post within the root canal and substantial internal tooth destruction; it was scheduled for endodontic surgery. Teeth 12 and 22 were root filled following the placement of a calcium hydroxide intracanal dressing for 21 days. Three attempts at root canal disinfection in tooth 11 were unsuccessful, and a persistent purulent drainage precluded completion of root canal treatment. Surgical enucleation of the periapical lesion was undertaken and the tissues submitted for histopathological examination. A diagnosis of COC was established based on the microscopic analysis. COC is an unusual benign lesion that represents 2% of all odontogenic lesions. Depending on the stage of development, it can mimic a large lesion associated with apical periodontitis and should therefore be considered in the differential diagnosis. In the case of COC, the definitive diagnosis can only be made with histopathological analysis.
  
  
  CONCLUSIONS
  Persistent apical periodontitis may be of nonendodontic origin. * Histological examination is essential to establish the cause of persistent apical periodontitis. * Calcifying odontogenic cyst can mimic apical periodontitis.
authors.affiliation: Department of Endodontics, Federal University of Goiás, Goiânia, GO, Brazil. estrela3@terra.com.br
authors.forename: C
authors.initials: C
authors.lastname: Estrela
authors.forename: D A
authors.initials: DA
authors.lastname: Decurcio
authors.forename: J A
authors.initials: JA
authors.lastname: Silva
authors.forename: E F
authors.initials: EF
authors.lastname: Mendonça
authors.forename: C R A
authors.initials: CR
authors.lastname: Estrela
mesh_terms: D000328:Adult; D002908:Chronic Disease; D003937:Diagnosis, Differential; D006801:Humans; D007180:Incisor / Q000473:pathology; D008297:Male; D008441:Maxillary Neoplasms / Q000150:complications* / Q000473:pathology / Q000628:therapy; D018333:Odontogenic Cyst, Calcifying / Q000150:complications* / Q000473:pathology / Q000628:therapy; D010485:Periapical Periodontitis / Q000150:complications* / Q000473:pathology / Q000628:therapy; D012390:Root Canal Therapy / Q000009:adverse effects / Q000379:methods; D014092:Tooth Root / Q000473:pathology*