O'Byrn B L, Sadowsky C, Schneider B, BeGole E A
Department of Orthodontics, University of Illinois at Chicago, College of Dentistry, USA.
Am J Orthod Dentofacial Orthop. 1995 Apr;107(4):394-400. doi: 10.1016/s0889-5406(95)70092-7.
A retrospective study was conducted to determine whether mandibular symmetry in adults with untreated unilateral posterior crossbite was different from that found in adults with untreated Class I malocclusions. Thirty adults, 18 years or older, with a unilateral posterior crossbite were compared with 30 adults exhibiting Angle Class I malocclusions. Skeletal and dental symmetry were assessed with submentovertex (SMV) radiographs, whereas condylar position within the glenoid fossa was analyzed with horizontally corrected tomograms. Relative to a mandibular coordinate system, the mandibular first molar on the crossbite side was found to be more lateral and relatively distal in comparison to the contralateral side. Skeletally, the mandible showed no asymmetry. Relative to the cranial floor, the mandible was "rotated" so that the condyle on the crossbite side was positioned relatively posteriorly in comparison to the contralateral side. A relative posterior positioning of the glenoid fossa was inferred, since there was no demonstrable mandibular skeletal asymmetry or condylar displacement within the fossa as shown on corrected tomograms in the crossbite group as compared with the Class I group. The results question whether it is appropriate to correct unilateral posterior crossbites in adults by orthodontic tooth movement alone, given the skeletal remodeling in the temporomandibular joint, which may have already occurred.
开展了一项回顾性研究，以确定未经治疗的单侧后牙反合成人的下颌对称性是否与未经治疗的安氏I类错合成人的下颌对称性不同。将30名18岁及以上的单侧后牙反合成人与30名表现为安氏I类错合的成人进行比较。使用颏顶位（SMV）X线片评估骨骼和牙齿的对称性，而使用水平校正断层扫描分析关节窝内的髁突位置。相对于下颌坐标系，发现反合侧的下颌第一磨牙比另一侧更偏向外侧且相对靠后。骨骼方面，下颌未显示不对称。相对于颅底，下颌发生了“旋转”，使得反合侧的髁突相对于另一侧位于相对后方。由于与I类组相比，反合组校正断层扫描显示颞下颌关节内没有明显的下颌骨骼不对称或髁突移位，因此推断关节窝存在相对后方的位置改变。鉴于颞下颌关节可能已经发生了骨骼重塑，这些结果质疑了仅通过正畸牙齿移动来矫正成人单侧后牙反合是否合适。
