title: Nucleolar organizer regions in selected odontogenic lesions.
abstract: OBJECTIVE
  The present study aimed to assess the usefulness of argyrophilic nucleolar organizer regions (AgNORs) as quantitative criteria in the diagnosis of odontogenic cysts and tumors.
  
  
  METHODS
  This descriptive cross-sectional study was done on archival paraffin blocks (n = 37), consisting of 10 conventional ameloblastomas, 7 cases of unicystic ameloblastoma, 10 odontogenic keratocysts, and 10 dentigerous cysts, all accessioned between 1994 and 2000.
  
  
  RESULTS
  The findings showed a significant statistical difference among the 4 lesions (P <.001). Conventional and unicystic ameloblastomas had a significantly higher (P <.05) number of AgNORs than odontogenic keratocysts and dentigerous cysts. No significant differences were observed within each group of tumors or cysts. The number of AgNORs was also significantly higher (P <.005) in the nuclei of basal layer cells of the epithelial lining of keratocysts than in the nuclei of parabasal layer cells. AgNORs in conventional and unicystic ameloblastomas were smaller but more broadly distributed, which may indicate higher proliferative activity.
  
  
  CONCLUSIONS
  AgNORs can be useful in the histopathologic differentiation of ameloblastomas from odontogenic cysts.
authors.affiliation: Shahid Beheshti University of Medical Sciences and Dental Research Center of Iran, Tehran, Iran.
authors.forename: Behnam
authors.initials: B
authors.lastname: Eslami
authors.forename: Masoud
authors.initials: M
authors.lastname: Yaghmaei
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Firoozi
authors.forename: Arash Shoja
authors.initials: AS
authors.lastname: Saffar
mesh_terms: D000564:Ameloblastoma / Q000473:pathology*; D003937:Diagnosis, Differential; D006801:Humans; D007573:Jaw Neoplasms / Q000473:pathology*; D009697:Nucleolus Organizer Region / Q000473:pathology*; D009807:Odontogenic Cysts / Q000473:pathology*; D009808:Odontogenic Tumors / Q000473:pathology*; D016622:Silver Staining