Department of Orthodontics, College of Dentistry, University of Illinois at Chicago, Chicago, IL, USA.
Am J Orthod Dentofacial Orthop. 2010 Mar;137(3):310-5. doi: 10.1016/j.ajodo.2008.05.017.
Palatal expanders have been advocated for spontaneous correction of some Class II malocclusions. However, little research has been done to determine whether correction or improvement actually occurs with expansion. Past research has not shown whether an anterior functional shift is achieved in patients who have Class II improvement. The objective of this study was to determine whether maxillary expansion causes spontaneous correction or improvement of a Class II malocclusion.
This was a retrospective study of subjects from an orthodontic office in which models are mounted (articulator) in centric occlusion and maximum intercuspation before and after treatment. The sample included Class II patients (n = 13; mean age, 10 years 3 months) who, during the preceding 2 years, had been treated with expansion alone. Study models made before and after expansion were measured to compare the centric occlusion to the maximum intersuspation position. Condyle position indicator paper was also used to determine whether there was a functional shift after expansion.
The only measurements with statistically significant changes from pretreatment to postexpansion were the maxillary intermolar widths. Seven of the 13 patients showed Class II improvement, but none had an anterior functional shift after expansion.
Maxillary expansion does not predictably improve Class II dental relationships.
腭扩展器已被提倡用于自发性矫正一些 II 类错畸形。然而，对于扩张后是否确实发生矫正或改善，研究甚少。过去的研究并未表明在 II 类改善的患者中是否实现了前功能移位。本研究的目的是确定上颌扩张是否会导致 II 类错畸形的自发性矫正或改善。
这是一项回顾性研究，对象来自于一个正畸办公室，其中模型在治疗前后以正中咬合和最大咬合位安装（牙合架）。样本包括 13 名 II 类患者（平均年龄 10 岁 3 个月），他们在过去 2 年中仅接受了扩张治疗。测量扩张前后的研究模型，以比较正中咬合与最大咬合位。还使用髁突位置指示纸来确定扩张后是否有功能移位。
从治疗前到扩张后的唯一具有统计学显著变化的测量值是上颌磨牙间宽度。13 名患者中有 7 名显示 II 类改善，但扩张后无任何前功能移位。
上颌扩张不能预测性地改善 II 类牙齿关系。
