Angle Orthod. 2020 Mar;90(2):233-238. doi: 10.2319/020219-74.1. Epub 2019 Aug 30.
The objective of this study was to compare the effects on upper dental arch size and shape after maxillary expansion with Hyrax, Quad-helix, and a differential opening expander in bilateral cleft lip and palate (BCLP) patients.
Seventy-five BCLP patients were divided into three groups: Hyrax (H), Quad-helix (QH), and Expander with differential opening (EDO). Digital models were obtained before (T1) and after 6 months (T2) of maxillary expansion. Twelve landmarks were placed by one investigator on T1 and T2 dental models of each group, and coordinates for each landmark were collected. For dental arch size analysis, centroid size of each dental arch at T1 and T2 was calculated from raw coordinates and was used as the measure of size. Procrustes Analysis was performed for dental arch shape analysis. Analysis of variance was used to compare the groups for size and shape differences ( < .05).
There were no significant dental arch size differences among the expanders at T1 or T2. Differences in arch shape were found between all groups at T2. Intragroup arch shape showed a significant variation for the QH and EDO groups. while it remained stable in the H group.
Both the QH and the EDO create dental arch shape changes with greater intercanine than intermolar increase. The H does not change the dental arch shape.
本研究旨在比较上颌扩张后对上颌牙弓大小和形状的影响，分别使用 Hyrax、Quad-helix 和差动开口扩弓器治疗双侧唇腭裂（BCLP）患者。
75 例 BCLP 患者分为 3 组：Hyrax（H）、Quad-helix（QH）和差动开口扩弓器（EDO）。在上颌扩张前（T1）和 6 个月后（T2）获得数字模型。由一位研究者在 T1 和 T2 牙模的每个组上放置 12 个标志点，并收集每个标志点的坐标。为了进行牙弓大小分析，从原始坐标计算 T1 和 T2 时每个牙弓的质心大小，并将其用作大小的度量。进行 Procrustes 分析进行牙弓形状分析。使用方差分析比较各组之间的大小和形状差异（<0.05）。
在 T1 或 T2 时，各扩弓器之间的牙弓大小没有显著差异。在 T2 时，所有组之间的牙弓形状都存在差异。QH 和 EDO 组的组内牙弓形状发生了显著变化，而 H 组的牙弓形状保持稳定。
QH 和 EDO 都可以改变牙弓形状，使尖牙间宽度增加大于磨牙间宽度。H 不能改变牙弓形状。
