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Figure 1. Definitions of condylar long axis (CLA) angle and molar rotation (MR) angle. (A) Line (1), which passes through the mediolateral center of the posterior mandible, was constructed by the least-squares method. The preliminary CLA, Line (2), is perpendicular to Line (1) and at a height where the condyle is at its widest. The CLA, Line (3), was obtained by rotating Line (2) within 10° in a clockwise or counterclockwise direction about the point where it intersects Line (1) and by fixing it at the position where the condyle is at its widest. (B) Line (4), the transspinosum axis; Line (5), the interspinosum axis, which was drawn perpendicular to the transspinosum axis from its midpoint as the reference line; Line (6), the median palatine suture. The CLA angle was defined as the angle between Line (3) and Line (5). (C) The angle was measured between the soft-tissue palatal midline and the line connecting the mesiobuccal and mesiolingual cusps of the molar. The reference line for measuring rotation angles was changed from the soft-tissue palatal midline to the same reference line used in the submentovertex measurements, Line (5), and then the molar rotation angle was recalculated.
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