Department of Orthodontics, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing, 100081, P.R. China.
Department of Dental Medical Center, China-Japan Friendship Hospital, Beijing, China.
Head Face Med. 2022 Sep 5;18(1):31. doi: 10.1186/s13005-022-00334-1.
Previous studies have reported inconsistent effects of premolar extraction on the oropharynx and hyoid bones. Currently, no strong evidence is available regarding the effect of extraction on upper airway size. Hence, the aim of this study was to analyse the effects of first premolar extraction on the oropharynx and hyoid bone positions in female adult patients, and further explored differences in oropharynx and hyoid bone changes among skeletal patterns.
The study population included 40 female adult patients who did not undergo extraction and 120 female adult patients who underwent extraction of four premolars; the including patients had four distinct sagittal and vertical skeletal patterns. Cone-beam computed tomography was performed before (T0) and after (T1) orthodontic treatment. Eight oropharynx variables and five hyoid bone variables were measured using Dolphin 3D Imaging software. Paired and independent t-tests were used to analyse measurements between timepoints and groups, respectively.
The oropharynx volume increased significantly in the extraction group; changes did not differ significantly between extraction and non-extraction groups. Oropharynx variables did not differ significantly at T0 among the four skeletal pattern groups. After orthodontic extraction treatment, the oropharynx volume increased significantly in the class I-norm and class I-hyper subgroups, but not in the class II-norm and class II-hyper subgroups. Significant increases were observed in the oropharynx volume and most constricted axial area from T0 to T1 in the moderate retraction group, but not in the maximum retraction group. Extraction patients exhibited significant posterior movement of the hyoid, particularly among maximum retraction patients.
In female adult patients, first premolar extraction tends to increase the oropharynx size and cause posterior movement of the hyoid bone, particularly in skeletal class I patients. For skeletal class II and hyperdivergent patients with a narrow oropharynx, first premolar extraction does not negatively influence oropharynx size or hyoid bone position. The differences of oropharyngeal changes between moderate retraction patients and maximum retraction patients were not significant.
先前的研究报告称，前磨牙拔除对鼻咽和舌骨的影响不一致。目前，尚无关于拔牙对上呼吸道大小影响的有力证据。因此，本研究旨在分析第一前磨牙拔除对女性成年患者鼻咽和舌骨位置的影响，并进一步探讨不同骨骼类型患者鼻咽和舌骨变化的差异。
研究人群包括 40 名未接受拔牙的女性成年患者和 120 名接受四颗前磨牙拔牙的女性成年患者；纳入的患者具有四种不同的矢状和垂直骨骼类型。在正畸治疗前后（T0 和 T1）进行锥形束 CT 检查。使用 Dolphin 3D 成像软件测量 8 个鼻咽变量和 5 个舌骨变量。采用配对和独立 t 检验分别分析组内和组间的测量值。
拔牙组的鼻咽容积显著增加；拔牙组与非拔牙组之间的变化无显著差异。在 T0 时，四个骨骼类型组之间的鼻咽变量没有显著差异。正畸拔牙治疗后，I 类正常和 I 类高角亚组的鼻咽容积显著增加，但 II 类正常和 II 类高角亚组没有显著增加。在中度回缩组中，从 T0 到 T1，鼻咽容积和最狭窄轴向面积显著增加，但在最大回缩组中没有显著增加。拔牙患者的舌骨明显向后移动，尤其是在最大回缩患者中。
在女性成年患者中，第一前磨牙拔除往往会增加鼻咽的大小，并导致舌骨向后移动，尤其是在 I 类骨骼患者中。对于鼻咽狭窄的 II 类和高角患者，第一前磨牙拔除不会对上呼吸道大小或舌骨位置产生负面影响。中度回缩患者和最大回缩患者之间的鼻咽变化差异不显著。
