骨性Ⅱ类错的颅底形态研究

目的用几何形态测量和传统头影测量2种方法,对Ⅱ类错的颅底形态进行研究。方法随机选取Ⅱ类与Ⅰ类错骨面型儿童的头颅定位侧位片各40张,描记颅底的9个标志点,数字化后,用Procrustes重叠法和薄板曲线法这2种几何形态测量法比较Ⅱ类与Ⅰ类错牙合的颅底形态。并用传统头影测量法对颅底的测量值进行分析。结果Ⅱ类与Ⅰ类错相比,颅底角无明显差别;后颅底发生显著变化,水平向后明显延长,伴向上的轻度抬高;前颅底区的S-SE段向前下方改变。结论Ⅱ类错的颅底形态有其自身特点;颅底形态影响Ⅱ类错的形成。

Cranial base morphology in subjects with class Ⅱ malocclusion

Objective To explore the cranial base morphology in subjects with classⅡ malocclusion by using the methods of geometric morphometrics and conventional cephalometrics. Methods The lateral cephalograms of 80 skeletal class Ⅰ and class Ⅱ malocclusions were selected randomly. The cephalograms were traced and nine homologous landmarks on cranial base were identified and digitized. Procrustes superimpasition and thin-plate spline were performed for localization of differences in cranial base morphology between class Ⅰ and class Ⅱ malocclusion. Conventional cephalometrics were used to explore the cranial base morphology in subjects with class Ⅱ malocclusion. Results Compared with class Ⅰ,cranial base angle in class Ⅱ was not significantly different. The greatest difference in morphology occurred in the posterior cranial base region,which consisted of horizontal expansion,and vertical compression. The anterior cranial base region,especially in the area of sphenoidal region,changed downwards. Conclusion The cranial base morphologies in class Ⅱ malocclusions were distinct and the cranial base affected the development of class Ⅱ malocclusion.