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The Dental Aesthetic Index (DAI) is an orthodontic index based on socially defined aesthetic standards. The primary aim of this study was to compare the prevalence of malocclusion using the DAI among three ethnic groups of Asian origin; Japanese, Chinese in Taiwan and Native Americans with white Americans. A secondary goal was to consider the possibility that genetic factors might be the cause of the characteristics of malocclusion in the ethnic groups of Asian origin. Malocclusion was evaluated in 1029 Japanese and 176 Chinese in Taiwan students utilising the DAI, and the findings were compared with those of Native Americans and white Americans. The DAI values of Japanese and Native Americans were significantly higher than those of Chinese in Taiwan and white Americans. The mean DAI values showed no common tendency among the three ethnic groups. The characteristics of malocclusion in each ethnic group were also evaluated by analysis of each of the 10 DAI component scores. The results revealed common characteristics of malocclusion in the three ethnic groups of Asian origin using white Americans as the standard. The findings in the present study suggest the possibility that genetic factors might have an influence on the characteristics of malocclusion.

The Standard DAI is an orthodontic index based on perceptions of dental aesthetics in the USA. The Standard DAI is a regression equation linking perceptions of the social acceptability of dental aesthetics with the objective intraoral measurements of ten occlusal traits. Since the Standard DAI is based on perceptions of dental aesthetics in the USA it can be used without modification only where perceptions of dental aesthetics are similar to those in the USA. This study was designed to determine whether perceptions of dental aesthetics of students in eleven diverse ethnic groups are similar to those of students in the USA. 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 Australian, Chinese, German, Japanese, Korean, Latvian, Native American, Singaporean Chinese, Singaporean Indian, Singaporean Malay, and Thai students. Their ratings were compared with the ratings of the same 25 stimuli by students in the USA. Spearman rank-order correlations ranged from 0.84 to 0.94. These correlations are sufficiently high to show that perceptions of dental aesthetics in all eleven ethnic groups are very similar to the perceptions of USA students. Therefore the Standard DAI can be used without modification in all eleven ethnic groups.

The Standard DAI is an orthodontic index based on perceptions of dental aesthetics in the USA. The Standard DAI is a regression equation linking perceptions of the social acceptability of dental aesthetics with the objective intraoral measurements of ten occlusal traits. Since the Standard DAI is based on perceptions of dental aesthetics in the USA it can be used without modification only where perceptions of dental aesthetics are similar to those in the USA. This study was designed to determine whether perceptions of dental aesthetics of students in eleven diverse ethnic groups are similar to those of students in the USA. 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 Australian, Chinese, German, Japanese, Korean, Latvian, Native American, Singaporean Chinese, Singaporean Indian, Singaporean Malay, and Thai students. Their ratings were compared with the ratings of the same 25 stimuli by students in the USA. Spearman rank-order correlations ranged from 0.84 to 0.94. These correlations are sufficiently high to show that perceptions of dental aesthetics in all eleven ethnic groups are very similar to the perceptions of USA students. Therefore the Standard DAI can be used without modification in all eleven ethnic groups.

The Standard DAI is an orthodontic index based on public perceptions of dental aesthetics in the USA and is a regression equation linking the relative social acceptability of dental appearance and the objective, physical measurements of ten occlusal traits. It can be used in surveys of need for orthodontic treatment and as a screening tool in public programmes providing orthodontic care. To determine if the Standard DAI could be used internationally, 200 stimuli (photographs of dental configurations) were rated for dental aesthetics by 413 Chinese students, 418 Latvian students and 428 Native Americans. To develop ethnic group-specific DAI equations these ratings were linked by regression procedures to the occlusal trait measurements available for each of the 200 stimuli. Using these equations, group-specific DAI scores were calculated for the 200 stimuli. At all levels on the DAI scale the percentage agreements, sensitivities and specificities ranged from 73 to 100 per cent indicating that the Standard DA can be used without modification to calculate DAI scores among Chinese, Latvians and Native Americans.

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.

Preliminary findings on the distribution of occlusal traits (COCSTOC-MOT) have been presented as measured on 1337 orthodontic models. These models were made from a sample representing more than 400 000 children ages 15 to 18 in Upstate New York (all of New York State with the exception of New York City). Some of the findings for occlusal traits in this survey are comparable to those from a representative sample of younger children representing the US population ages 6--11 years. For comparable traits differences between the findings in New York State and for the United States were: Openbite--1 per cent higher in the US sample. Overjet 6 mm or more--5.7 per cent higher in the US sample. Neutro-occlusion--7 per cent more in the US sample. Disto-occlusion--8 per cent more in the US sample. Mesio-occlusion--8 per cent more in the US sample. Differences in findings between these surveys are assumed to be largely due to the fact that the current survey measured occlusal traits in the permanent dentition; whereas, the US survey measured those traits in the mixed dentition. Some of the traits found in the mixed dentition are believed to be self-correcting. Statistically determined means and medians for some of the occlusal traits of COCSTOC indicate that there is considerable variation from ideal occlusion found in a large population.