RESUMO
The purpose of this study was to develop a principal component analysis-based adaptive minimum Euclidean distances (PAMED) approach to establish an optimal object reference frame for symmetrical alignment of the dental arch during computer-aided surgical simulation (CASS). It was compared with our triangular methods and the standard principal component analysis (PCA) method. Thirty sets of maxillary digital models were used. Midsagittal and occlusal planes were ranked by three experienced evaluators based on their clinical judgment. The results showed that for the midsagittal plane, all three evaluators ranked "ideal" for all 30 models with the PAMED method, 28 with the triangular method, and at least 11 with the PCA method. For the occlusal plane, one evaluator ranked all 30 models "ideal" with both the PAMED and the PCA methods while the other two evaluators ranked all 30 models "ideal" with the triangular method. However, the differences among the three methods were minimal. In conclusion, our PAMED method is the most reliable and consistent approach for establishing the object reference frame for the dental arch in orthognathic surgical planning. The triangular method should be used with caution because it can be affected by dental arch asymmetry. The standard PCA method is not recommended.