Korean J Orthod.  2009 Apr;39(2):72-82. 10.4041/kjod.2009.39.2.72.

The structural change in the hyoid bone and upper airway after orthognathic surgery for skeletal class III anterior open bite patients using 3-dimensional computed tomography

Affiliations
  • 1Department of Orthodontics, College of Dentistry, Yonsei University, Korea.
  • 2Department of Orthodontics, College of Dentistry, Oral Science Research Center, The Institute of Cranio-facial Deformity, Yonsei University, Korea. yumichael@yuhs.ac

Abstract


OBJECTIVE
The purpose of this study was to investigate the structural changes of the hyoid bone and upper airway after orthognathic surgery for skeletal class III anterior open bite patients, and make comparisons with normal occlusion. METHODS: Pre- and post-operative computed tomography (CT) examinations were performed on 12 skeletal class III anterior open bite patients who were treated with mandibular setback osteotomy. Using the V-works 4.0(TM) program, 3-dimensional images of the total skull, mandible, hyoid bone, and upper airway were evaluated. RESULTS: In the Class III openbite group, the hyoid bone were all positioned anteriorly, compared to the Normal group (p < 0.05). The angle between the hyoid plane and mandibular plane in the Class III openbite group before surgery was greater than in the Normal group (p < 0.05), and the difference increased after surgery (p < 0.01). In the Class III openbite group, the volume of the upper airway decreased after surgery (p < 0.001) and the volume of the upper airway was smaller than the Normal group before and after surgery (p < 0.001). CONCLUSIONS: The narrow upper airway space in skeletal Class III openbite patients decreased after mandibular setback osteotomy. This may affect the post-surgical stability.

Keyword

Three-dimensional computed tomography (3D CT); Skeletal class III openbite; Hyoid bone; Upper airway
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