The Dental Aesthetic Index (DAI) is an orthodontic index based on socially defined aesthetic standards. The DAI score, which divides the continuous index score in orthodontic care programs and malocclusion prevalence studies into four malocclusion severity levels, is used for measurement. The purpose of this study was to measure the DAI score of jaw deformity patients in the Department of Orthodontics, Dental Hospital, Tsurumi University. The subjects consisted of 314 patients, who were classified into 11 types according to the characteristics of their malocclusion. The DAI score was calculated on gnathostatic models of the subjects according to the WHO guidelines. The mean score of all the subjects was 49.1 ± 15.8. Subjects with a score of more than 90% were classified into Grade 3 or 4, which represented severe malocclusion and very severe or handicapping malocclusion. However, less than 10% of subjects were classified into Grade 1 or 2, even though they showed severe horizontal deformity. The results clearly suggest that the DAI score is useful for evaluating the necessity of orthodontic treatment in patients with anteroposterior and vertical skeletal deformities. Nevertheless, the DAI score has limitations for evaluating horizontal skeletal deformities.
