目的研究固定包绕式螺旋扩弓器扩弓前后牙弓宽度、长度变化及两者间的关系。方法选取上牙弓狭窄患者33例,戴用固定包绕式螺旋扩弓器扩大上牙弓,在扩弓前后的上颌石膏模型上测量牙弓宽度变化和牙弓长度变化。结果扩弓前后牙弓宽度增值为4.58±1.23mm,牙弓长度增值5.64±1.35mm。结论使用固定包绕式螺旋扩弓器扩大上牙弓后,牙弓长度增值大于牙弓宽度增值。 Objective To study the change of dental arch width and length before and after expansion of fixed-wrap helix expansion device and their relationship. Methods Totally 33 patients with upper arch stenosis were enrolled in this study. The upper arch was expanded with a fixed wrap-around spiral expander and the dental arch width and arch length were measured before and after maxillofacial gypsum expansion. Results The increase of dental arch width was 4.58 ± 1.23mm before and after expansion and the increment of dental arch was 5.64 ± 1.35mm. Conclusion The use of a fixed wrap around the spiral dilator to expand the upper arch, the dental arch length greater than the increment value of arch width.