Malocclusion in individuals with mental subnormality--a review.

The occurrence of malocclusion in individuals with mental disability poses an additional obstacle to social acceptance; not only from an esthetic point of view, but also in that it compromises all aspects of oral function. This review examines the reported prevalence of malocclusion in individuals with mental subnormality including Down syndrome, from 1981 to 2013, assessed according to Angle's classification, the Dental Aesthetic Index (DAI), the Index of Orthodontic Treatment Need (IOTN) and certain malocclusions. Although widely reported in many studies, it is still quite difficult to compare the exact proportion of occlusal anomalies and orthodontic treatment need among mentally challenged individuals. This is due partly to the multiplicity of measurement methods and the difficulty in standardizing criteria. Several studies have reported higher prevalence of malocclusion including anterior open bite, anterior cross bite, severe malocclusions in mentally challenged individuals, especially those with Down syndrome. The findings have been varied and attributed to musculoskeletal abnormalities, altered cranial-base relationships, premature tooth loss or eruption, lip incompetence, etc. Future research needs to be devoted to determining exactly why malocclusion is higher among individuals with mental subnormalities. It will be a challenge to identify the preventable factors among multiple complex etiologies to reduce these disparities.