The aim of this study was to evaluate the prevalence and severity of malocclusion and orthodontic treatment needs in a sample of 12-year-old South African school children using the Dental Aesthetic Index (DAI), and to assess the relationship between malocclusion and certain socio-demographic variables. The sample comprised 6142, 12-year-old children attending school in seven of the nine provinces of South Africa. For each subject the standard demographic information such as gender, population group, location type and employment status of the parents were collected, after which an intra-oral examination for occlusal status using the DAI was performed. The results showed that 47.7 per cent of the children in the sample presented with good occlusion or minor malocclusion, just over 52.1 per cent presented with identifiable malocclusion, a DAI score larger than 26. Of these, 21.2 per cent had definite malocclusion, 14.12 per cent had severe malocclusion and 16.89 per cent had very severe or handicapping malocclusion. Malocclusion as defined in this study was found to be significantly associated with the different provinces, the different population groups in South Africa, gender and dentition stage, but not with the location type or the employment status of parents. The results of the individual variables showed that anterior maxillary and mandibular irregularity occurred in more than 50 per cent of the sample. More than 40 per cent of the children examined showed signs of crowding. Spacing in the incisal segments occurred in almost 28 per cent of the sample and maxillary midline diastema was present in 16.66 per cent of the sample. At the age of 12 years, Black children, showed a higher prevalence of maxillary midline diastema, larger than 2mm, than their White, Coloured and Asian counterparts. A maxillary midline diastema, larger than 2mm, was more prevalent in 12-year-old females than in males. Thirty one per cent of the sample had an increased overjet larger than 3mm and a severe overjet of 6mm or more occurred in only 2.18 per cent of the sample. More Black 12-year-old children presented with an edge-to-edge anterior relationship and significantly less Black children had an increased overjet. Mandibular overjet affected only 10.43 per cent of the sample and was more prevalent in the late mixed dentition stage than in the early permanent dentition stage. Anterior openbite occurred in 7.7 per cent of the sample and ranged from 1mm to 8mm. Almost 44 per cent of the sample had a antero-posterior molar relation discrepancy. The results of this study indicated a high prevalence of malocclusion in 12-year-old South African children. The findings provide reliable base-line data regarding the prevalence, distribution and severity of malocclusion as well as useful epidemiological data on the orthodontic treatment needs of 12-year-old children in selected rural and urban areas in South Africa. The inclusion of occlusal traits as part of the index provided an opportunity to assess several occlusal characteristics in 12-year-old South African children, separately.
Thesis (MChD (Orthodontics))--University of Pretoria, 2004.