Prevalence of orthodontic asymmetries.

Epidemiological studies of the occlusal status of the US population do not include the prevalence of orthodontic asymmetries. To estimate the magnitude of dental and facial asymmetries in adolescents with no history of orthodontic treatment, data were analyzed from two mass orthodontic screenings that had been conducted on public schoolchildren in Florida. An analysis of orthodontic records of patients in treatment at the Virginia Commonwealth University graduate orthodontic clinic provided prevalence data on dental and facial asymmetries in a population of orthodontic patients. In the Florida studies, the two screenings yielded 5,817 untreated children (mean age, 9.3 +/- 0.8 years) and 861 untreated children (mean age, 14.4 +/- 0.5 years). Sagittal molar asymmetry was found in 30% of the children in the first screening and in 23% in the second screening. Additional asymmetry assessments in the second screening showed 12% facial asymmetry and 21% noncoincidence of dental midlines. Among orthodontic patients, the most common asymmetry trait was mandibular midline deviation from the facial midline. This occurred in 62% of patients, followed, in descending order of frequency, by lack of dental midline coincidence (46%), maxillary midline deviation from the facial midline (39%), molar classification asymmetry (22%), maxillary occlusal asymmetry (20%), mandibular occlusal asymmetry (18%), facial asymmetry (6%), chin deviation (4%), and nose deviation (3%).