title: A clinical review of crossbite in an orthodontic population.
abstract: BACKGROUND
  Crossbite is a common occlusal anomaly. It may occur either anteriorly or posteriorly and may be either dental or skeletal in origin.
  
  
  OBJECTIVE
  To determine the pattern and frequency of crossbite occurrence in an orthodontic population.
  
  
  METHODS
  This was a retrospective study of 633 patients, 288 males (45.5%) and 345 (54.5%) attending a Lagos orthodontic clinic over a five-year period. Information obtained on each patient included age, sex and occlusal variables such as overjet, overbite and tooth-bone ratio.
  
  
  RESULTS
  Out of the 633 patients seen 189 (29.9%) were recorded to have at least one tooth in crossbite. Anterior crossbite occurred in 125 (66.1%) of the affected patients while posterior crossbite was recorded in 37 (19.6%). Patients presenting with anterior and posterior crossbite constituted 27 (14.3%) of patients. Unilateral crossbite was slightly more frequently than bilateral crossbite. A total of 445 teeth were recorded in crossbite with the permanent maxillary lateral incisor being the most frequently affected tooth constituting 33.9% of the teeth in crossbite. The number of teeth in crossbite per patient ranged from 1 to 8, a single tooth in crossbite being most commonly occurring. Crossbite was most frequently seen in patients presenting with Class I malocclusion.
  
  
  CONCLUSIONS
  Crossbite was a frequently occurring anomaly in the Lagos population, with anterior crossbite being more common. There appear to be gender or age difference in occurrence of crossbite in our population.
authors.affiliation: Department of Child Dental Health, College of Medicine, University of Lagos, P.M.B. 12003, Lagos, Nigeria.
authors.forename: O O
authors.initials: OO
authors.lastname: Dacosta
authors.forename: I L
authors.initials: IL
authors.lastname: Utomi
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D005260:Female; D006784:Hospitals, Teaching; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008310:Malocclusion / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology*; D008875:Middle Aged; D009549:Nigeria / Q000453:epidemiology; D011159:Population Surveillance; D012189:Retrospective Studies; D017678:Sex Distribution; D055815:Young Adult