侧方Nance弓治疗单侧后牙反[牙合]

目的利用模型测量分析侧方Nance弓扩弓前、后牙弓宽度和上颌第一磨牙冠颊倾度及扭转度的变化,评价侧方Nance弓的临床效果。方法选择12个单侧后牙反[牙合]病例,用侧方Nance弓扩弓。测量矫治前后第一双尖牙、第二双尖牙、第一磨牙宽度变化以及第一磨牙冠颊倾度及扭转度的变化。结果扩弓4月左右,反[牙合]侧牙弓得到有效的扩大,反[牙合]侧第一双尖牙、第二双尖牙、第一磨牙宽度平均分别增加了3.2、3.02、.8 mm;正常侧磨牙宽度无明显扩大;反侧第一磨牙牙冠颊向倾斜（9.7±3.6）°和近中颊向扭转（5.6±2.7）°,而正常侧变化不明显。结论侧方Nance弓是矫治单侧后牙反[牙合]的简单而有效的方法。

Treatment of Unilateral Posterior Cross-bite with Lateral Nance Arch

Objective To evaluate the expansion effects produced by lateral Nance arch.Methods Twelve patients with unilateral posterior cross-bite were enrolled in the study.The width of dental arch,crown tipping,and crown mesiodistal rotation before and after the expansion was measured.Results The dental arches of all the patients were effectively expanded within four months or so.The width of the first premolar,the second premolar,and the maxillary first molar to medline in the crossbite side was respectively increased by 3.2,3.0,2.8 mm.The width in the normal side,however,had no obvious expansion.The maxillary first molar in the crossbite side showed a buccal crown tipping of（9.7±3.6） and mesiobuccal rotation of（5.6±2.7）,while the normal side had no obvious change.Conclusion Lateral Nance arch is an effective and simple method to correct unilateral posterior cross-bite.