Methods Measurement of 11 dental models was performed, midline of palate was defined as central line, the distance of every contact point to the midline was measured in each side.

• 方法测量11例骨性下颌前突伴偏斜患者治疗前模型,将上颌腭中缝作为中线标准,测量牙弓两侧同名牙接触点到腭中缝的距离,观测牙弓的对称性。