Evaluation of the postoperative stability of a counter-clockwise rotation technique for skeletal class II patients by using a novel three- dimensional position-posture method.

The aim of this study is to evaluate the postsurgical stability of skeletal class II patients after performing a counter-clockwise rotational (CCWR) procedure for the maxilla-mandibular complex (MMC) by using a novel Three-dimensional (3D) Position-Posture(P-P) measuring method. Twenty-five patients (5 males and 20 females) were included in this study. The postoperative CT scans of the skull were taken before surgery(T0), 3-7 days (T1), 3 months (T2), and 6 months (T3) after surgery. Specific anatomic landmarks were chosen to determine the position of the segments, while three equally perpendicular planes were created to describe their posture. The results show that the linear relapse of maxillary landmarks during the follow-up were acceptable (≤0.5 mm). The relapse of maxillary pitch plane at 6-months follow-up is 1.52°, which is acceptable. There was a significant pitch plane relapse of the mandibular-body segment with an average of 1.86° between T1 and T2 models, 3.28° between T1 and T3 models. There was no significant difference between roll and yaw planes during the follow-up. We therefore conclude that the P-P method could be used to accurately analyze the postsurgical stability of skeletal class II orthognathic surgery cases. For CCWR procedures, it was also shown that the there is a tendency for recurrence most specially on the body of the mandible.