title: Types and incidence of human periapical lesions obtained with extracted teeth.
abstract: OBJECTIVE
  To determine (1) the frequency of the incidence of abscess, granuloma, and radicular cyst among human periapical lesions obtained with extracted teeth; and (2) whether periapical cysts occur in two categories when histologically analyzed in relation to the root canals.
  
  
  METHODS
  A total of 256 lesions were analyzed. The specimens were decalcified and embedded in plastic. Serial sections or step-serial sections were prepared, and the sections were evaluated on the basis of predefined histopathologic criteria.
  
  
  RESULTS
  The 256 specimens consisted of 35% periapical abscess, 50% granuloma, and 15% cysts. The latter occurred in two categories, the apical true cysts and the apical pocket cysts.
  
  
  CONCLUSIONS
  These results show (1) the low incidence of radicular cysts among periapical lesions as against the widely held view that almost half of all periapical lesions are cysts; and (2) the occurrence of two classes of radicular cysts. We are of opinion that the pocket cysts may heal after root canal therapy but the true cysts are less likely to be resolved by conventional root canal treatment.
authors.affiliation: Institute of Oral Structural Biology, University of Zurich, Switzerland.
authors.forename: P N
authors.initials: PN
authors.lastname: Ramachandran Nair
authors.forename: G
authors.initials: G
authors.lastname: Pajarola
authors.forename: H E
authors.initials: HE
authors.lastname: Schroeder
mesh_terms: D003648:Decalcification Technique; D003786:Dental Pulp Cavity / Q000473:pathology; D004848:Epithelium / Q000473:pathology; D006801:Humans; D015994:Incidence; D008214:Lymphocytes / Q000473:pathology; D008867:Microtomy; D009504:Neutrophils / Q000473:pathology; D010482:Periapical Abscess / Q000453:epidemiology* / Q000473:pathology; D010484:Periapical Granuloma / Q000453:epidemiology* / Q000473:pathology; D010950:Plasma Cells / Q000473:pathology; D016613:Plastic Embedding; D011842:Radicular Cyst / Q000145:classification / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D012390:Root Canal Therapy; D013557:Switzerland / Q000453:epidemiology; D014081:Tooth Extraction