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The standard dental aesthetic index (DAI) is an orthodontic treatment need index based on perceptions of dental aesthetics in the United States. It is a regression equation that links perceptions of the social acceptability of dental aesthetics with the objective intraoral measurements of ten occlusal traits. For the index to be universally acceptable, the perceptions of dental aesthetics in other countries must be similar to those of the United States. This study was designed to determine whether the perceptions of dental aesthetics of Nigerian students are similar to those of different groups of the US population. The same 25 stimuli (photographs of dental configurations, a subset of the 200 stimuli used in deriving the standard DAI equation) were rated for dental aesthetics by Nigerian students. Their ratings were compared with ratings of the same 25 stimuli by US parents, students and orthodontists. Spearman rank-order correlations ranged from 0.75 to 0.84. These correlations were highly significant (P<0.0001), and showed that the perceptions of dental aesthetics of Nigerian students were very similar to those of the US groups. The study therefore concluded that standard DAI could be used as a screening tool and without modification in epidemiological surveys among Nigerians.

The Dental Aesthetic Index (DAI) was used to evaluate malocclusion in Japanese high school students (n = 409, ages 15-18 yr). The purpose of this study was to obtain basic data concerning malocclusion in Japanese high school students. This study used a sample of students from randomly selected urban and rural high schools in Japan's Kyushu district. The DAI scores for urban and rural high school students, as well as the total DAI scores from these two areas were significantly higher than that of American high school students. These results showed that the number of students with an acceptable dental appearance among Japanese high school students is significantly lower than among American high school students. This indicates a higher need for orthodontic treatment among Japanese high school students.

A method for determining the social acceptability for dental appearance across the full range of occlusal conditions found in a natural population was developed and tested. The strategy used in developing the Social Acceptability Scale of Occlusal Conditions (SASOC) was to present photographs of 100 dental study models to a large sample of high school students (n = 880) and their parents (n = 403) whose responses were measured by a semantic differential instrument. After refinement of the semantic differential instrument scale scores were derived for each study model by computing the mean individual scores. Ranks were assigned to the mean scores. The Pearsonian correlation obtained between parent and student subsamples was 0.95. The reliability and validity of SASOC were assessed. COCSTOC measures of specific occlusal traits for these 100 study models are available. The future task involves the development of a highly reliable regression equation for predicting social acceptability scores from a small number of objective physical measurements.

Occlusal conditions which vary significantly from accepted social norms for dental appearance may socially handicap an individual. An instrument is required by which socially unacceptable occlusal conditions can be identified by members of the public who have internalized society's norms for acceptable dental appearance. The factors identified in this paper make it possible to select a reasonable number (100) of models for constructing a measurement instrument which depicts the full range of occlusal patterns found in a natural population for use in assessing the social acceptability of occlusal conditions. This paper presents the methodology and process used to identify individual occlusal traits which tend to occur together in trait combinations or independently and their range from "normal" to extreme. Data on the frequency distribution of the individual COCSTOC measurements found in a natural population was subjected to a factor analysis which identified 18 occlusal patterns (combinations of traits) and five unique or independent traits or anomalies.

Scores for three malocclusion indices (HLD, TPI and OI) and Orthodontist Judgment (OJ) were available for the 100 orthodontic study models utilized in the development of SASOC, the Social Acceptability Scale of Occlusal Conditions. The ability of SASOC to predict need for treatment using OJ as a standard was compared to the ability of HLD, TPI and OI to predict OJ's decisions. In addition, determinations of need for treatment of each of the 100 models using HLD, OI and OJ were compared to SASOC's rankings for the public's perceptions of aesthetic acceptability. Finally, the agreement of HLD, OI and OJ with each other in assessing need for treatment was compared. Results indicated: 1) that SASOC's, HLD's, TPI's and OI's "hit rate" in predicting OJ ranged between 73% and 81%; 2) HLD's, OI's and OJ's assessment of malocclusion paralleled lay perceptions of aesthetic acceptability (SASOC), and 3) there were differences of agreement among HLD, OI and OJ as to which cases had a definite need for treatment. There was more agreement on cases which did not have a definite need for treatment than on those which did. A tool which assesses only the aesthetic component of occlusal configurations was judged to be more suitable in the study of the social and psychological impact of malocclusion than indices and orthodontist judgment which include professional criteria as well as aesthetics in their assessments of malocclusion.