替牙列早期骨性前牙反与正常的下颌运动轨迹研究

Study of mandibular movement trace in skeletal anterior reverse malocclusion and normal occlusion in early stage of mixed dentition

目的观测替牙列早期骨性前牙反者与正常者的下颌运动轨迹,并比较两者的差异。方法采用下颌运动轨迹超声波记录系统(ARCUSdigma系统),对处于替牙列早期的32例骨性前牙反者和19例正常者的空载开口和前伸运动进行比较。结果在空载运动中,处于替牙列早期的骨性前牙反组运动中心的典型运动轨迹较正常平坦,在运动的初始阶段出现向上位移,在矢状位上的垂直向及水平向最大位移均小于正常组,但差异不显著;在空载开口运动中,骨性前牙反组切点的典型运动轨迹为先垂直下降,然后前移一段距离后再垂直下降,与正常组存在差异,在矢状位上的水平向最大位移与正常组存在显著差异。在空载前伸运动中,处于替牙列早期的骨性前牙反组运动中心的典型运动轨迹较正常组平坦,在矢状位上的垂直向及水平向最大位移均小于正常组,但差异不显著;在空载前伸运动中,骨性前牙反组切点的典型运动轨迹较正常组平坦,在矢状位上的水平向最大位移显著小于正常组。结论处于替牙列早期的骨性前牙反与正常研究对象运动中心及切点的空载开口和前伸运动轨迹存在差异。这些差异是由于研究对象牙颌前部不同的咬合状态所造成的。

Objective To observe the differences of mandibular movement trace between normal occlusion and skeletal anterior reverse malocclusion in early stage of mixed dentition. Methods A new kind of mandibular movement analysis system, ACRUSdigma system, was used in the study. The kinematic center which can represent the translation and rotation of the condylar and the incisal points was used as reference point to compare the difference of the empty opening and protrusion mandibular movement trajectory of 32 skeletal anterior reverse bite malocclusions and 19 normal occlusions in early stage of mixed dentition. Results For the kinematic center, the typical trajectory of the skeletal anterior reverse bite malocclusion moved more horizontally than that of the normal subject in the entire empty opening and protrusion movements on the sagittal plane For the incisal point, the typical trajectory of the skeletal anterior reverse bite malocclusions went down almost vertically from the intercuspal position （ICP）. On the other hand, the path of the ICP of the skeletal anterior re verse bite malocclusion differed from that of the normal occlusion subject. The typical trajectory of the skeletal anterior reverse bite malocclusion moved more horizontally than that of normal subject in the empty protrusion movement. Conclusions There are some differences of the empty opening and protrusion mandibular movement trajectory between the skeletal anterior reverse bite malocclusions and the normal occlusions in the early stage of mixed dentition, which might be caused by different occlusal station, different anatomic morphology of tern poromandibular joint, and different neuromuscular feedback systerm.