title: A multi-centre evaluation of multiple supernumerary premolar prevalence.
abstract: OBJECTIVE
  The occurrence of multiple supernumerary teeth is rare and often found in association with syndromes such as cleidocranial dysplasia, Gardner's syndrome or cleft lip and palate. Few examples of non-syndromal multiple supernumerary teeth have been reported. The aim of this multi-centre study was to investigate the prevalence of supernumerary premolar teeth in non-syndromic patients and to investigate the association between the presence of supernumerary premolar teeth and malocclusion type in a Turkish population.
  
  
  METHODS
  The clinical records and panoramic radiographs of 10,700 patients (referred to three different university hospitals) were retrospectively examined for the presence of supernumerary premolars. Age, gender, orthodontic malocclusion type, the number of supernumerary premolars (two or more), the distribution, location, position (vertical, horizontal, inverted, mesio-angular), surgical approach, and related complications (pain, cystic changes, root resorption, or eruption disturbance of adjacent teeth) were recorded.
  
  
  RESULTS
  Forty-two cases (13 Class I, 17 Class II, 12 Class III) of multiple mandibular supernumerary premolars in patients without an associated syndrome were detected. A total of 97 (27 Class I, 41 Class II, 29 Class III) supernumerary premolar teeth were found, with a prevalence of 0.39%. No statistical difference was found related to gender, malocclusion type and supernumerary premolars (p > 0.05). The majority of the extra premolars were located in the mandible, which was statistically significant (p < 0.05).
  
  
  CONCLUSIONS
  The present study revealed that the prevalence of multiple supernumerary teeth was 0.39%. The most frequently impacted premolars were found in the mandible and more often associated with Class II malocclusions in the examined Turkish population.
authors.forename: Kaan
authors.initials: K
authors.lastname: Gunduz
authors.forename: Hakan
authors.initials: H
authors.lastname: Avsever
authors.forename: Kaan
authors.initials: K
authors.lastname: Orhan
authors.forename: Gözde
authors.initials: G
authors.lastname: Canitezer
authors.forename: Aydan
authors.initials: A
authors.lastname: Acikgoz
authors.forename: Ulas
authors.initials: U
authors.lastname: Oz
authors.forename: Muhammet
authors.initials: M
authors.lastname: Midilli
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000002:abnormalities*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000453:epidemiology; D008312:Malocclusion, Angle Class II / Q000453:epidemiology; D008334:Mandible / Q000473:pathology; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D014095:Tooth, Impacted / Q000453:epidemiology; D014096:Tooth, Supernumerary / Q000453:epidemiology*; D014421:Turkey / Q000453:epidemiology; D055815:Young Adult