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The aims of this study were to measure the distribution, prevalence and the severity of malocclusion and treatment need amongst randomly selected (n = 703) rural and urban Nigerian children aged 12-18 years (mean 14.0 +/- 1.84) using the dental aesthetic index (DAI), and to assess whether malocclusion was affected by age, gender and socio-economic background. Data were collected according to the method recommended by WHO. Most of the children (77.4 per cent) had a dental appearance which required no orthodontic treatment. Over 13 per cent fell into the group where treatment for malocclusion is considered to be 'elective'. However, a substantial proportion (9.2 per cent) of the population had severe to handicapping malocclusion where treatment is 'highly desirable' or 'mandatory'. There were no statistically significant differences (P > 0.05) in DAI scores between age groups, gender and socio-economic background. This study also found that Nigerian adolescents had better dental appearance and less orthodontic treatment need compared with the Caucasian and Oriental populations.

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) 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.

This article compares and contrasts two orthodontic indices, the Index of Orthodontic Treatment Need (IOTN), and the Dental Aesthetic Index (DAI). Both contain esthetic and clinical criteria. Both accept the premise that a significant benefit of orthodontic treatment is improved esthetics and, by inference, social and psychological well-being. Both have as their goal the identification of children most in need of orthodontic treatment subsidized by public funds. The first part of this article describes the IOTN, its development, reliability, and validity. The second section describes the DAI, its development, reliability, and validity. The third part of the article compares and contrasts the indices. There are a number of differences between the IOTN and the DAI. In the IOTN, the esthetic component is a separate instrument from the dental health component. The unique aspect of the DAI is its linking of people's perceptions of esthetics with anatomic trait measurements by regression analysis to produce a single score obviating the need, as in the IOTN, for two separate scores that cannot be combined. Both components of the IOTN have only three grades, "no need," "borderline need," and "definite need." The IOTN cannot rank order cases with greater or lesser need for treatment within grades. In contrast, DAI scores can be rank ordered on a continuous scale and can differentiate cases within severity levels. With the IOTN, about a third of British schoolchildren would be found eligible for treatment in public programs. Providing publicly funded orthodontic care to as many as a third of the schoolchildren would not be feasible in the United States.

The Dental Aesthetic Index (DAI) is an orthodontic index based on socially defined aesthetic standards. It is useful in both epidemiological surveys to identify unmet need for orthodontic treatment and as a screening device to determine priority for subsidized orthodontic treatment. An earlier study established the score of 36 on the DAI scale to identify handicapping malocclusions. The purpose of the present study was to determine decision points on the DAI scale that identify malocclusion severity levels less severe than handicapping. Two sources of data were used: 1) The frequency distribution of DAI scores on a probability sample of 1306 study models representing the untreated occlusions found in half a million adolescents. 2) The percent distribution of US youths aged 12-17 by specified case severity reported in an assessment of the occlusion of youths by the National Center for Health Statistics (NCHS). The decision points separating specific case severities on the DAI scale were determined by relating the proportions of the NCHS population with specified case severities to the cumulative percentages of the frequency distribution of DAI scores on the 1306 models. The NCHS report found 45.8 percent of the sample to have normal or minor malocclusion with no need or slight need for treatment. DAI scores 25 and below corresponded to that proportion of the sample. The NCHS report found 25.2 percent of the sample to have definite malocclusion with treatment being elective. DAI scores between 26 and 30 corresponded to that proportion of the sample. The NCHS report found 13 percent of the population to have severe malocclusion with treatment highly desirable. Fifteen percent were included in this category. DAI scores 31 to 35 corresponded to that proportion of the sample.

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.

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.

The Dental Aesthetic Index (DAI) is an orthodontic index based on socially defined aesthetic standards. The DAI is useful in both epidemiological surveys to identify unmet need for orthodontic treatment as shown by its use by WHO in ICS-II and as a screening device to determine priority for subsidised orthodontic treatment. The purpose of this study was to determine a decision point on the DAI scale that predicts the clinical judgments of orthodontists in separating handicapping from non-handicapping malocclusion. Orthodontists' decisions were available on a sample of 1306 models representing untreated occlusions found in half a million children. DAI scores were calculated for each model. By correlating orthodontists' decisions with DAI scores a cut-off point was established. Agreements between DAI scores and orthodontists' decisions were best at the 86th percentile on the DAI scale. The DAI score of 36 at the 86th percentile yielded an 88 per cent agreement, a specificity of 93 per cent and a sensitivity of 54 per cent. Cases with scores of 36 and higher would be considered handicapping according to the DAI.

Clinical impressions by Indian Health Service (IHS) dentists of a greater frequency of severe dental malrelations among Native Americans than in the general US population have never been objectively confirmed. This study uses the DAI as the standard to determine whether there is a greater prevalence of severe malocclusions among Native Americans. Four hundred eighty-five Native American students in grades 7-12 from two remote sites--Pine Ridge, SD, and Many Farms, AZ--and one nonremote site--Lapwai, ID--were scored for the DAI. The mean scores from each reservation, as well as the mean score from the three reservations combined, were significantly higher, indicating poorer aesthetics, than the mean DAI score from a large sample of the general US population. These data confirm the clinical impressions of IHS dentists that Native Americans residing on reservations have significantly poorer dental aesthetics than the aesthetics found in the general US population; therefore, Native Americans have greater needs for orthodontic treatment.

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.

To be truly useful, an index must be applicable universally without modification. The data presented in this article support the use of the standard DAI without modification to assess need for orthodontic treatment in both developing and industrialized countries. When students from Thailand, Australia, the German Democratic Republic, and Native Americans residing on Indian reservations rated the same 25 occlusal stimuli (photographs of dental configurations) for dental aesthetics, their ratings of these stimuli when arranged in rank order were highly correlated with those of US students. These 25 occlusal stimuli were a subset of the original 200 occlusal stimuli used in deriving the standard DAI regression equation. This article presents data indicating that when a Native American DAI was derived based on Native American ratings of the same 200 occlusal stimuli used in deriving the standard DAI, the Native American DAI and the standard DAI had the same ten components (orthodontic measurements) and strikingly similar regression coefficients (weights). Further analysis indicated that the two equations were sufficiently similar to justify using the standard DAI to obtain DAI scores on Native Americans and to estimate the relative social acceptability of their dental aesthetics. If ratings for dental aesthetics for the full set of 200 stimuli were available for each of the countries where only 25 were rated, we expect that, as in the case of Native Americans, a country-specific DAI, if computed, would be sufficiently similar to the standard DAI that no modification would be needed to allow use of the standard DAI in that country.(ABSTRACT TRUNCATED AT 250 WORDS)

An instrument developed by Jenny et al. (1980) for rating the public's perceptions of the social acceptability of a wide variety of occlusal configurations was administered to children and adults in Australia, the German Democratic Republic and the United States of America and also to US orthodontists. Mean scores for the 7 groups of subjects from the 3 countries were arranged in rank order from the least socially acceptable to the most socially acceptable and compared. The results indicate that use of the social acceptability scale of occlusal conditions (SASOC) is a highly reliable method for scoring and rank-ordering the aesthetic acceptability of occlusal morphologies. Spearman rank-order correlation coefficients between the ranking of SASOC stimuli by all 7 groups of subjects from the 3 countries ranged from 0.85 to 0.97. The probability of such correlations occurring by chance is less than 1 in 10000 (P less than 0.0001). SASOC proved capable of rank-ordering a wide range of occlusal morphologies for aesthetics with excellent consistency along the entire spectrum from the least acceptable to the most socially acceptable in all 3 countries. The data indicate that norms for socially acceptable dental appearance are essentially the same in Australia, the German Democratic Republic and the United States of America.

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.

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.