{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T18:30:16Z","timestamp":1787164216592,"version":"build-2736575974"},"reference-count":47,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2023,10,23]],"date-time":"2023-10-23T00:00:00Z","timestamp":1698019200000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>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\u2019s correlation test (alpha = 0.05).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      A significant reduction in oropharyngeal, velopharyngeal, and hypopharyngeal airway dimensions was noted in groups I, III, and IV (\n                      <jats:italic>P<\/jats:italic>\n                      \u00a0&lt;\u00a00.001), which was correlated with the magnitude of retraction of upper and lower incisors (\n                      <jats:italic>r<\/jats:italic>\n                      \u00a0=\u00a00.6\u00a0\u2212\u00a00.8). In group II, a significant increase was observed in oropharyngeal and velopharyngeal dimensions (\n                      <jats:italic>P<\/jats:italic>\n                      \u00a0&lt;\u00a00.001). A significant increase in nasopharyngeal dimensions occurred in all groups (\n                      <jats:italic>P<\/jats:italic>\n                      \u00a0&lt;\u00a00.001). Also, in groups I and III, the position of hyoid bone changed downwards and backwards, which was correlated with reduction in airway dimensions (\n                      <jats:italic>r<\/jats:italic>\n                      \u00a0=\u00a00.4\u00a0\u2212\u00a00.6).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>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.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.7717\/peerj.15960","type":"journal-article","created":{"date-parts":[[2023,10,23]],"date-time":"2023-10-23T04:53:35Z","timestamp":1698036815000},"page":"e15960","source":"Crossref","is-referenced-by-count":9,"title":["Effect of premolar extraction and anchorage type for orthodontic space closure on upper airway dimensions and position of hyoid bone in adults: a retrospective cephalometric assessment"],"prefix":"10.7717","volume":"11","author":[{"given":"Omid","family":"Mortezai","sequence":"first","affiliation":[{"name":"Department of Orthodontics, Dental faculty, Qazvin University of Medical Sciences, Qazvin, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zeynab","family":"Shalli","sequence":"additional","affiliation":[{"name":"Department of Orthodontics, Dental faculty, Qazvin University of Medical Sciences, Qazvin, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maryam","family":"Tofangchiha","sequence":"additional","affiliation":[{"name":"Dental Caries Prevention Research Center, Qazvin University of Medical Sciences, Qazvin, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ahad","family":"Alizadeh","sequence":"additional","affiliation":[{"name":"Medical Microbiology Research Center, Qazvin University of Medical Sciences, Qazvin, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Francesco","family":"Pagnoni","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillo Facial Sciences, Sapienza University of Rome, Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rodolfo","family":"Reda","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillo Facial Sciences, Sapienza University of Rome, Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luca","family":"Testarelli","sequence":"additional","affiliation":[{"name":"Department of Oral and Maxillo Facial Sciences, Sapienza University of Rome, Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4443","published-online":{"date-parts":[[2023,10,23]]},"reference":[{"issue":"3","key":"10.7717\/peerj.15960\/ref-1","doi-asserted-by":"publisher","first-page":"142","DOI":"10.1016\/j.sdentj.2019.11.004","article-title":"Evaluation of the airway space changes after extraction of four second premolars and orthodontic space closure in adult female patients with bimaxillary protrusion\u2014a retrospective study","volume":"32","author":"Aldosari","year":"2020","journal-title":"The Saudi Dental Journal"},{"issue":"1","key":"10.7717\/peerj.15960\/ref-2","doi-asserted-by":"publisher","first-page":"7","DOI":"10.4103\/jos.JOS_140_17","article-title":"Pharyngeal airway dimensional changes after premolar extraction in skeletal class II and class III orthodontic patients","volume":"7","author":"Alkawari","year":"2018","journal-title":"Journal of Orthodontic Science"},{"issue":"5","key":"10.7717\/peerj.15960\/ref-3","doi-asserted-by":"publisher","first-page":"853","DOI":"10.2319\/101711-646.1","article-title":"First premolar extraction effects on upper airway dimension in bimaxillary proclination patients","volume":"82","author":"AlMaaitah","year":"2012","journal-title":"The Angle Orthodontist"},{"issue":"4","key":"10.7717\/peerj.15960\/ref-4","doi-asserted-by":"publisher","first-page":"393","DOI":"10.1016\/s0889-5406(96)70121-x","article-title":"The decision to extract: part II. 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