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Abstract：
This study aimed to assess the effect of premolar extraction and anchorage type for orthodontic space closure on upper airway dimensions and position of hyoid bone in adults by cephalometric assessment.
This retrospective study was conducted on 142 cephalograms of patients who underwent orthodontic treatment with premolar extraction in four groups of (I) 40 class I patients with bimaxillary protrusion and maximum anchorage, (II) 40 class I patients with moderate crowding and anchorage, (III) 40 class II patients with maximum anchorage, and (IV) 22 skeletal class III patients with maximum anchorage. The dimensions of the nasopharynx, velopharynx, oropharynx, and hypopharynx, and hyoid bone position were assessed on pre- and postoperative lateral cephalograms using AudaxCeph v6.1.4.3951 software. Data were analyzed by the Chi-square test, paired t-test, and Pearson\'s correlation test (alpha = 0.05).
A significant reduction in oropharyngeal, velopharyngeal, and hypopharyngeal airway dimensions was noted in groups I, III, and IV (P < 0.001), which was correlated with the magnitude of retraction of upper and lower incisors (r = 0.6 - 0.8). In group II, a significant increase was observed in oropharyngeal and velopharyngeal dimensions (P < 0.001). A significant increase in nasopharyngeal dimensions occurred in all groups (P < 0.001). Also, in groups I and III, the position of hyoid bone changed downwards and backwards, which was correlated with reduction in airway dimensions (r = 0.4 - 0.6).
According to the present results, extraction orthodontic treatment affects upper airway dimensions and hyoid bone position. Maximum anchorage decreases airway dimensions while moderate anchorage increases airway dimensions.
This retrospective study was conducted on 142 cephalograms of patients who underwent orthodontic treatment with premolar extraction in four groups of (I) 40 class I patients with bimaxillary protrusion and maximum anchorage, (II) 40 class I patients with moderate crowding and anchorage, (III) 40 class II patients with maximum anchorage, and (IV) 22 skeletal class III patients with maximum anchorage. The dimensions of the nasopharynx, velopharynx, oropharynx, and hypopharynx, and hyoid bone position were assessed on pre- and postoperative lateral cephalograms using AudaxCeph v6.1.4.3951 software. Data were analyzed by the Chi-square test, paired t-test, and Pearson\'s correlation test (alpha = 0.05).
A significant reduction in oropharyngeal, velopharyngeal, and hypopharyngeal airway dimensions was noted in groups I, III, and IV (P < 0.001), which was correlated with the magnitude of retraction of upper and lower incisors (r = 0.6 - 0.8). In group II, a significant increase was observed in oropharyngeal and velopharyngeal dimensions (P < 0.001). A significant increase in nasopharyngeal dimensions occurred in all groups (P < 0.001). Also, in groups I and III, the position of hyoid bone changed downwards and backwards, which was correlated with reduction in airway dimensions (r = 0.4 - 0.6).
According to the present results, extraction orthodontic treatment affects upper airway dimensions and hyoid bone position. Maximum anchorage decreases airway dimensions while moderate anchorage increases airway dimensions.
摘要：
■本研究旨在通过头颅测量评估来评估用于正畸间隙闭合的前磨牙拔除和锚固类型对成人上气道尺寸和舌骨位置的影响。
■这项回顾性研究是对四组（I）40例I类双颌前突和最大支抗的患者中142例接受前磨牙拔除正畸治疗的患者进行的，（二）40例中度拥挤支抗的Ⅰ类患者，（三）最大支抗的Ⅱ类患者40例，（IV）22名具有最大支抗的骨骼III类患者。鼻咽部的尺寸,Velopharynx,口咽,和下咽,使用AudaxCephv6.1.4.3951软件在术前和术后外侧脑电图上评估舌骨位置。数据分析采用卡方检验,配对t检验，和皮尔逊相关检验(α=0.05)。
■口咽明显减少，咽喉,下咽气道尺寸在第一组中记录，III,和IV（P<0.001），这与上切牙和下切牙的退缩幅度相关（r=0.6-0.8）。在第二组中，口咽部和腭咽部尺寸显著增加(P<0.001).所有组均显著增加鼻咽部尺寸(P<0.001)。此外，在第一组和第三组中，舌骨的位置向下和向后改变，这与气道尺寸的减少相关（r=0.4-0.6）。
■根据目前的结果，拔牙正畸治疗影响上气道尺寸和舌骨位置。最大支抗减少气道尺寸，而中度支抗增加气道尺寸。
■这项回顾性研究是对四组（I）40例I类双颌前突和最大支抗的患者中142例接受前磨牙拔除正畸治疗的患者进行的，（二）40例中度拥挤支抗的Ⅰ类患者，（三）最大支抗的Ⅱ类患者40例，（IV）22名具有最大支抗的骨骼III类患者。鼻咽部的尺寸,Velopharynx,口咽,和下咽,使用AudaxCephv6.1.4.3951软件在术前和术后外侧脑电图上评估舌骨位置。数据分析采用卡方检验,配对t检验，和皮尔逊相关检验(α=0.05)。
■口咽明显减少，咽喉,下咽气道尺寸在第一组中记录，III,和IV（P<0.001），这与上切牙和下切牙的退缩幅度相关（r=0.6-0.8）。在第二组中，口咽部和腭咽部尺寸显著增加(P<0.001).所有组均显著增加鼻咽部尺寸(P<0.001)。此外，在第一组和第三组中，舌骨的位置向下和向后改变，这与气道尺寸的减少相关（r=0.4-0.6）。
■根据目前的结果，拔牙正畸治疗影响上气道尺寸和舌骨位置。最大支抗减少气道尺寸，而中度支抗增加气道尺寸。
