替牙列早期骨性前牙反早期治疗结束后下颌运动轨迹的变化

Study of mandibular movement trace in skeletal anterior reverse bite malocclusion after the early stage orthodontic treatment of mixed dentition

目的观测替牙列骨性前牙反早期治疗前后下颌运动轨迹的变化,为骨性前牙反早期矫治提供依据。方法采用下颌运动轨迹超声波记录系统(ARCUSdigma系统),以兼顾髁状突平移和转动两种运动的运动中心和切点为下颌运动参考点,对处于替牙列早期的30例骨性前牙反者早期正畸治疗后以6个自由度对其空载开口和前伸运动进行比较研究。结果在空载开口运动中,当早期治疗结束时,运动中心的向上位移消失,在矢状位上的垂直向及水平向位移均增大,但无显著差异。当早期治疗结束时,切点的典型运动轨迹为先前移,再垂直下降,经过一段距离后再向后下方下降。在空载前伸运动中,当早期治疗结束时,运动中心的运动轨迹发生变化,为先向前下方运动,在矢状位的水平向位移显著大于矫治前。切点的典型运动轨迹变为先向前下方运动,在矢状位上的水平位移显著大于治疗前。结论处于替牙列早期的骨性前牙反患者,经早期口外支抗前牵治疗后,上下颌骨的相对位置发生改变,随着口内颌垫的不断磨除,逐步建立起的正常前部咬合引导关系使下颌功能运动趋于正常化。

Objective To study the differences between the mandibular movement in empty opening and protrusion trace of the skeletal anterior reverse malocclusion before and after the early protraction treatment in early stage of mixed dentition. Methods ACRUSdigma system, a kind of ultrasonic mandibular movement record system, was used in the study. The kinematic center which can represent the translation and rotation of the condylar and the incisal points were used as reference point to compare the difference of the empty opening and protrusion mandibular movement trajectory of 30 individuals with skeletal anterior reverse bite malocclusions before and after the early protraction facemask treatment. Results For the kinematic center, the typical trajectory was changed, the upper movement disappeared and the distances between vertical and horizontal movements were increased at the end of the treatment in the empty opening movement on the sagittal plane. In the empty protrusion movement, the interplanar distance of the kinematic center was increased significantly on the sagittal plane. For the incisial point, it moved ahead at first and then downward vertically in the empty protrusion movement, and the interplanar distance was increased significantly on the sagittal plane in the empty opening movement. Conclusions By giving the protraction treatment, the relation of upper mandible and submaxilla of the skeletal anterior reverse bite malocclusions is changed. During the later stage of the treatment, for the occlusal splint was ground off, the normal occlusial inducement is built, which affords the rebuilding of temporomandibular joint （TMJ）, ligaments and muscles. The trajectory also becomes normal. The normal trajectory may supply a better environment for the development and rebuilding of jaw, TMJ, ligaments and muscles.