Original ArticlesThe Envelope of Segmental Movement and Airway Changes After Mandibular Anterior Subapical Osteotomy in Skeletal Class II Protrusion PatientsJeong, Hyun Joo MSD*; Kim, Seong-Hun PhD†; Choi, Byung-Joon PhD‡; Han, Seung-Heui MSD*; Ahn, Hyo-Won PhD§Author Information *Department of Dentistry, Graduate School, Kyung Hee University †Department of Orthodontics, Kyung Hee University School of Dentistry ‡Department of Oral and Maxillofacial Surgery, Kyung Hee University School of Dentistry §Department of Orthodontics, Kyung Hee University School of Dentistry, Seoul, Republic of Korea. Address correspondence and reprint requests to Hyo-Won Ahn, PhD, Department of Orthodontics, Kyung Hee University School of Dentistry, Kyung Hee Dae-ro 23, Dongdaemun-Gu, Seoul 02447, Republic of Korea; E-mail: firstname.lastname@example.org Received 26 July, 2019 Accepted 10 October, 2019 The authors report no conflicts of interest. Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.jcraniofacialsurgery.com). Journal of Craniofacial Surgery: May 2020 - Volume 31 - Issue 3 - p 668-672 doi: 10.1097/SCS.0000000000006159 Buy SDC Metrics Abstract Introduction: This study aimed to determine the envelope of anterior segmental movement and changes in the inferior pharyngeal airway space (IPAS) and position of the hyoid bone following mandibular anterior subapical osteotomy (ASO) under local anesthesia in skeletal Class II patients with protrusion. Methods: The subjects were 33 skeletal Class II adult patients with lip protrusion. They were treated by extraction of 4 premolars and mandibular ASO under local anesthesia. Surgical movement of mandibular anterior segment and IPAS after surgery was evaluated by mandibular superimposition using lateral cephalograms between before and immediately after surgery. The depth of osteotomy and overlapping ratio were measured. Results: The mean retraction of the mandibular incisor was 4.04 mm at the tip and 4.29 mm at the root apex. The mean vertical movement of the mandibular incisor was 3.33 mm intrusion at the tip and 3.42 mm at the root apex. The axis of the mandibular incisor did not change significantly. Patients with deep curve of Spee showed significantly more intrusion of incisors, whereas the incisor axis became more proclined. The IPAS became narrower, and the hyoid bone moved downward after surgery. The decreased IPAS was positively correlated with retraction of root apex and proclination of the mandibular incisors. Conclusion: To establish precise surgical treatment objectives, a balance between the amount of intrusion and changes in axis should be sought after considering anatomical limitations. Mandibular ASO should be performed with caution in skeletal Class II patients vulnerable to airway-related problems. © 2020 by Mutaz B. Habal, MD.