ESTABLISHING MALOCCLUSION SEVERITY LEVELS ON THE DENTAL AESTHETIC INDEX (DAI) SCALE

The Dental Aesthetic Index (DAI) is an orthodontic index based on soci ally defined aesthetic standards. It is useful in both epidemiological surveys to identify unmet need for orthodontic treatment and as a scr eening device to determine priority for subsidized orthodontic treatme nt. An earlier study established the score of 36 on the DAI scale to i dentify handicapping malocclusions. The purpose of the present study w as to determine decision points on the DAI scale that identify maloccl usion severity levels less severe than handicapping. Two sources of da ta were used: 1) The frequency distribution of DAI scores on a probabi lity sample of 1306 study models representing the untreated occlusions found in half a million adolescents. 2) The per cent distribution of US youths aged 12-17 by specified case severity reported in an assessm ent of the occlusion of youths by the National Center for Health Stati stics (NCHS). The decision points separating specific case severities on the DAI scale were determined by relating the proportions of the NC HS population with specified case severities to the cumulative percent ages of the frequency distribution of DAI scores on the 1306 models. T he NCHS report found 45.8 per cent of the sample to have normal or min or malocclusion with no need or slight need for treatment. DAI scores 25 and below corresponded to that proportion of the sample. The NCHS r eport found 25.2 per cent of the sample to have definite malocclusion with treatment being elective. DAI scores between 26 and 30 correspond ed to that proportion of the sample. The NCHS report found 13 per cent of the population to have severe malocclusion with treatment highly d esirable. Fifteen per cent were included-in this category. DAI scores 31 to 35 corresponded to that proportion of the sample.