The purpose of this study was to find out and evaluate discrepancies between preorthodontic prediction values and actual postorthodontic values and factors contributing to it in 45 patients(17 male, 28 female) who were diagnosed as skeletal Class III malocclusion and received presurgical orthodontic treatment and orthognathic surgery at Yonsei university dental hospital. Lateral cephalograms were analyzed at pretreatment(T1), orthodontic prediction(T2), immediately before surgery(T3) and designated the landmark as coordinates of X and Y axes. The samples were divided according to ALD, upper and lower incisor inclination(Ul to SN, IMPA), COS, extraction, the position of extracted teeth and the statistical significance was tested to find out the factors contributing to-the prediction.
The results were as follows
1. Differences between preorthodontic prediction values and actual postorthodontic values(T2-T3) were statistically
significant(p<0.05) in the x coordinates of U6mbc, Llx and in y coordinates of Uli, Ulx, U6me, U6mbc, L6mbc 2. The accuracy of prediction is relatively higher in horizontal changes compared to vertical changes.
3. The statistical significance(p<0.05) between prediction and actual values. is observed more in the landmarks of
the maxilla than the mandible.
4. Differences between prediction and actual values of incisor and first molar were statistically significant(p<0.05) according to extraction vs non-extraction, extraction type, ALD in the maxilla and according to ALD, IMPA in the mandible.
Discrepancies between preorthodontic prediction values and actual postorthodontic values and factors contributing to the prediction must be considered in treatment planning of Cl III surgical patients to increase the accuracy of prediction. Furthermore future investigations are needed on the prediction of vertical changes.
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