Premolar extraction in orthodontics and its effect on mandibular kinematics: Axiographic data

The purpose of this study was to test whether orthodontic premolar teeth extraction had an influence on mandibular kinematics. Forty-five orthodontically treated patients (P4ex group) with premolar teeth extraction were compared with 45 paired untreated controls (P4 group). Symmetric movements were registered in 3D for both right and left sides, using a diagnostic computerised axiograph CADIAX. We measured condyle symmetric movements, specially mandibular lateral translation during protrusion/retrusion (∆Y) and speech (SP-∆Y), and the amount of rotation (SP-G) and length of the movement during speech (SP-3D). Finally the amount of Retral stability was measure (R-ST). All the mmeasurements were taken for the right (R) and left (L) sides . We found that orthodontic extraction of first premolars might disrupt jaw kinematics by increasing the amount of lateral deviations of the tracings describing the condylar movements in 25% of the cases

本研究旨在探究正畸前磨牙拔除对下颌运动学是否具有影响。研究选取了45名经过正畸治疗且拔除前磨牙的患者（P4ex组）与45名未经治疗的对照者（P4组）进行对比。利用CADIAX诊断计算机化轴位影像仪，对左右两侧的对称性运动进行三维登记。我们测量了髁突对称性运动，特别是下颌在 protrusion/retrusion（∆Y）和言语（SP-∆Y）过程中的横向位移，以及旋转量（SP-G）和言语过程中的运动长度（SP-3D）。最终，我们测量了后退稳定性（R-ST）。所有测量均在右侧（R）和左侧（L）进行。研究发现，正畸拔除第一前磨牙可能导致25%的病例中下颌运动学受到影响，表现为描述髁突运动的轨迹横向偏差增加。