title: Prevalence and risk factors of mucous retention cysts in a Brazilian population.
abstract: OBJECTIVE
  The aim of this study was to estimate the prevalence and analyse the risk factors of mucous retention cysts (MRCs) of the maxillary sinus.
  
  
  METHODS
  From November 2002 to May 2007, 6293 panoramic radiographs were taken and retrospectively reviewed to estimate the prevalence of MRCs and to analyse risk factors (month, relative air humidity and mean temperature). The months in which MRCs occurred were recorded and analysed. The Spearman rank correlation coefficient was used to correlate MRCs with relative air humidity, environmental temperature and month (significance level R(2)>0.85).
  
  
  RESULTS
  Of the 6293 radiographs analysed, 201 (3.19%) images were suggestive of MRCs. No significant correlation was found between MRCs and relative humidity (R(2) = 0.15) of the air or temperature (R(2) = 0.40). The months with the highest numbers of MRC cases were September, October and November.
  
  
  CONCLUSIONS
  The prevalence of MRCs was low, and no statistical correlation was found between MRCs and relative humidity of the air, mean temperature or month.
authors.affiliation: Brazilian Dentistry Association, Basília, DF, Brazil.
authors.forename: C D
authors.initials: CD
authors.lastname: Rodrigues
authors.forename: G F
authors.initials: GF
authors.lastname: Freire
authors.forename: L B
authors.initials: LB
authors.lastname: Silva
authors.forename: M M
authors.initials: MM
authors.lastname: Fonseca da Silveira
authors.forename: C
authors.initials: C
authors.lastname: Estrela
mesh_terms: D000328:Adult; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008443:Maxillary Sinus / Q000000981:diagnostic imaging*; D009078:Mucocele / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D010254:Paranasal Sinus Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015995:Prevalence; D011862:Radiography, Panoramic; D012307:Risk Factors; D012621:Seasons