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THE DENTAL AESTHETIC INDEX (DAI)
Although a number of classifications and indices have been suggested for characterisation of dento-facial anomalies, only a few have been adopted for general use outside the country of origin. This is partly due to considerable variation in socio-culturally-determined perceptions and the reactions to dentofacial appearance(53,54,55,56).
Although numerous indices have been developed, none as yet has been accepted universally(51). In the meantime, one of the indices available must necessarily be chosen. The selection of an index for measuring any condition is dependent upon two main factors:
• The objective of the investigation i.e. the nature of the information required.
• The ability of the examiner to consistently reproduce the diagnosis on which the index is based(18).
ESTABLISHING MALOCCLUSION SEVERITY LEVELS ON THE DENTAL AESTHETIC INDEX (DAI) SCALE
During the 1970s, the importance of psychosocial factors in the assessment of malocclusion was acknowledged in the USA and internationally(57,58). It was said that the definition of malocclusion was not one to be made by orthodontic clinicians alone. There was believed to be a salient need for the development of an orthodontic index containing psychosocial as well as clinical criteria(59,60).
The relationship between dental aesthetics and psychological and social wellbeing has been noted by many investigators. Helm(61) for instance, noted that ‘Concern for dental appearance is an essential factor in determining psychosocial need for orthodontic treatment’. Brook and Shaw(62) stated that the assessment of a patients treatment need must include aesthetic impairment and by inference psychosocial need for orthodontic treatment.
Stricker et al(63) concluded that the psychosocial consequences of malocclusion due to unacceptable aesthetics may be as serious or even more serious than the biological problems.
In response to the demand for an orthodontic index that includes psychosocial criteria in assessing need for orthodontic care and for use in epidemiological surveys, Cons et al(44) developed the Dental Aesthetic Index (DAI) that integrated the psychosocial and physical elements of malocclusion. The Dental Aesthetic Index (DAI) is an orthodontic index based on socially defined aesthetic norms. Which is a regression equation that links mathematically the public’s perceptions of dental aesthetics with the objective physical measurements of the occlusal traits associated with malocclusion. The DAI is particularly sensitive to occlusal conditions that have the potential for causing psychological or social dysfunction.
The DAI includes the hypotheses that socially derived norms for acceptable dental appearance set the standard for evaluation of acceptable levels of dental aesthetics and that the conditions of malocclusion is socially defined by the deviation of occlusal configurations from social norms. Extreme deviations from acceptable dental appearance should have a negative impact on social, psychological and physical function. The components of the DAI regression equation and their actual and rounded regression coefficients (weights) are shown in Table 2-1. The Standard DAI regression equation calls for the measured components of the DAI to be multiplied by their rounded regression coefficients (weights); the summation of their products and the addition of a constant number to the total. The resulting sum is the DAI score. The regression equation for obtaining a DAI score is: DAI score = 6(missing incisors, canines and premolars) + (crowding) + (spacing) + 3(diastema) + (largest maxillary irregularity) + (largest mandibular irregularity) + 2(anterior maxillary overjet) + 4(anterior mandibular overjet) + 4(anterior open bite) + 3(antero-posterior molar relationship) + 13.
FINDINGS OF PREVIOUS ORTHODONTIC EPIDEMIOLOGICAL STUDIES IN SOUTHERN AFRICA
Jacobson(73) studied 460 crania and mandibles of South African Blacks in the Department of Anatomy at the University of the Witwatersrand, Johannesburg. The study material originated from adults, ranging in age between 16 and 108 years. The results of this study showed that the percentage of well-aligned teeth was 76.2 and 67.1 respectively in a total of 63 maxillae and 70 mandibles. In 96.4 per cent of males and 97.4 per cent of females a Class I type occlusion (neutroclusion) was recorded, while a Class II type was recorded in less than three per cent of the sample in both sexes. Since, criteria for assessing malocclusion had not been standardised yet, no comparative tables could be compiled for other population groups.
The first extensive epidemiological study of the occlusion and treatment needs of 14-year-old children living in Pretoria were done in 1979 by Zietsman(14). The sample consisted of 490 white children. The Angle system(35) for classifying the antero-posterior dental relationship was used. Other features recorded on a specially designed form were; the absence, rotations or displacements of individual teeth, crowding or spacing of 3mm or more in each of the posterior segments of both arches, the presence of crossbite or open bites and an upper central diastema of 1mm or more. Based on the presence and severity of the above features each case was examined and classified subjectively as having either a normal occlusion or a malocclusion. Roughly, one in four (23.3 per cent) children were found to have a normal occlusion, but 76.7 per cent needed orthodontic treatment.
Zietsman(74) undertook three further pilot studies. A sample of 119 Black subjects was drawn from the Tswana ethnic group of Bophuthatswana and two samples, each of 51, 14-year-olds were drawn from a school for Asians and a school for Coloured children. The results showed that 54.6 per cent of Black, 39.2 per cent of Coloured and 23.3 per cent of Asian children had a normal occlusion according to Angle’s(35) standards. Treatment was essential or necessary for 25 per cent of Blacks, 47 per cent of Coloureds and 49 per cent of Asians.
Hirschowitz, Rashid and Cleaton-Jones(75) undertook a study to determine the dental status of a sample of 402, 12-year-old urban Black school children from a lower socio-economic group living in Soweto. Malocclusion was scored as present or absent, only gross anomalies were scored and cases were subdivided into Class I, II and III. Malocclusion was present in only 11 per cent of children, of which 79.5 per cent had Class I; 12.4 per cent had Class II and 9 per cent had Class III malocclusions. The authors concluded that the low prevalence of malocclusion might be due to the well-developed jaws and a tendency to bimaxillary protrusion, which was regarded as normal for the population studied.
CHAPTER 1 PROBLEM STATEMENT, AIM, GOALS AND RATIONALE
1.1 INTRODUCTION
1.2 AIM
1.3 GOALS
1.4 PROBLEM STATEMENT
1.5 RATIONALE
CHAPTER 2 REVIEW OF THE LITERATURE
2.1 EPIDEMIOLOGY OF MALOCCLUSION
2.2 EPIDEMIOLOGICAL ORTHODONTIC SURVEY METHODS
2.3 THE DENTAL AESTHETIC INDEX (DAI)
2.4 EPIDEMIOLOGY OF MALOCCLUSION IN OTHER COUNTRIES – DEFINED BY THE DENTAL AESTHETIC INDEX
2.5 FINDINGS OF PREVIOUS ORTHODONTIC EPIDEMIOLOGICAL STUDIES IN SOUTHERN AFRICA
CHAPTER 3 RESEARCH METODOLOGY
3.1 INTRODUCTION
3.2 NATURE AND SCOPE OF THE SURVEY
3.3 SAMPLE
3.4 INDEX FOR ORTHODONTIC STATUS AND TREATMENT NEED ASSESSMENTS
3.5 CALIBRATION AND TRAINING
3.6 ETHICAL MATTERS
3.7 STATISTICAL ANALYSIS
CHAPTER 4 RESULTS AND DISCUSSION
4.1 INTRODUCTION
4.2 REPRODUCIBILITY
4.3 COMPOSITION OF THE SAMPLE IN TERMS OF DENTITION STAGE
4.4 PREVALENCE AND TREATMENT NEED OF MALOCCLUSION IN SOUTH AFRICA
4.5 PREVALENCE OF MALOCCLUSION IN THE DIFFERENT PROVINCES OF SOUTH AFRICA
4.6 PREVALENCE OF MALOCCLUSION BY GENDER
4.7 PREVALENCE OF MALOCCLUSION BY POPULATION GROUP IN SOUTH AFRICA
4.8 PREVALENCE OF MALOCCLUSION BY LOCATION TYPE
4.9 PREVALENCE OF MALOCCLUSION BY EMPLOYMENT STATUS OF PARENTS
4.10 ANALYSIS OF THE DIFFERENT VARIABLES OF THE DAI
CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS
CONCLUSIONS AND RECOMMENDATIONS
LIRERATURE REFERENCES
