Abstract
Objective The primary purpose of this study was to statistically evaluate age, ethnic and sex differences in the prevalence of clinically meaningful malocclusions among adults. Setting and Sample Population A random sample of 8804 untreated US adults between 17 and 46 years of age was selected from the Third National Health and Nutrition Examination Survey data. Materials & Methods Three ethnic (non-Hispanic White, non-Hispanic Black and Mexican Americans) and three age (17-26, 27-36 and 37-46 years) groups were evaluated. Subjects with and without clinically meaningful malocclusions were categorized based on the established cut-off values. Chi-square analyses were performed to determine differences in prevalence. Results The prevalence of clinically meaningful mandibular incisor irregularity, overjet and overbite increased significantly (P < 0.05) with age, while posterior crossbite decreased. There were statistically significant ethnic differences in the prevalence of incisor irregularity, overbite, overjet, open bite and reverse overjet. Males had a significantly higher prevalence of clinically meaningful mandibular incisor irregularity, overbite, open bite and reverse overjet than females. One-third of US adults exhibited no clinically meaningful malocclusions. Conclusions There are age, ethnic and sex differences in the prevalence of clinically meaningful malocclusions that characterize approximately two-thirds of untreated US adults.