RESUMO
Bimaxillary proclination (BP) is a relatively common malocclusion in Negroid and Mongloid populations but rarely seen in Caucasians. for this reason, orthodontic publications (in English) offer very little guidance on treatment of BP based on sound evidence. BP patients present for orthodontic treatment at the University of the West Indies School of Dentistry frequently, so a need and opportunity for research to be done to provide a better quality health service for them exists. To address this, the study described here has been proposed. The aim of this work was to determine the effects of extractions on the facial profile and relapse in patients treated for BP. Female BP patients will be treated with orthodontic fixed appliances (FAs) and compared as two groups of 50. Extractions of 4 premolars will be done before FA treatment in 50 patients; no extractions will be performed in the age and race-matched control group. Lateral cephalometric radiographs will be made: before and after FA treatment; immediately after retention is stopped; and 5 years after retention. Intra-oral measurements and dental casts (study models) will also be made at these times. Computer-aided production of composite silhoutte images from the cephalometric radiographs will be used to determine lay people's perception of facial profile changes in the two groups also. Statistical analysis of measurements made using the radiographs, silhoutte images, clinical examination and study models will be done. The results (from analysis of cephalometric measurements, lay people's perceptions, incisor irregularity, molar relationship and overjet measurements) should show whether or not extraction therapy has a deleterious effect on the facial profile and increases risk of relapse in BP patients. (AU)
