Cervical spine posture and Twin-block treatment

Abstract

I read with great interest the excellent article entitled, Evaluation of cervical spine posture after functional therapy with twin-block appliances: A retrospective cohort study (Kamal AT, Fida M. Am J Orthod Dentofacial Orthop 2019;155:656-61). These authors found that craniocervical posture became more upright after Twin-block therapy. Craniocervical posture was also found to be related to the size of the mandible, which in turn has been related to airway size.1Trenouth M.J. Desmond S.R. A cephalometric evaluation of oropharyngeal airway changes during Twin-block appliance treatment.Int J Dent Oral Sci. 2016; S4004: 22-30Google Scholar Timms2Timms D. Letter to the editor.Am J Orthod Dentofacial Orthop. 1990; 97 (Re Wenzel A, Williams S, Ritzau M. Relationships of changes in craniofacial morphology, head posture, and nasopharyngeal airway size following mandibular osteotomy. Am J Orthod Dentofacial Orthop 1989;96:138-43): 29A-30AAbstract Full Text PDF PubMed Scopus (5) Google Scholar postulated that a reduction in oropharyngeal airway after mandibular setback surgery might be compensated for by cervical hyperflexion, and this was later confirmed by several studies.2Timms D. Letter to the editor.Am J Orthod Dentofacial Orthop. 1990; 97 (Re Wenzel A, Williams S, Ritzau M. Relationships of changes in craniofacial morphology, head posture, and nasopharyngeal airway size following mandibular osteotomy. Am J Orthod Dentofacial Orthop 1989;96:138-43): 29A-30AAbstract Full Text PDF PubMed Scopus (5) Google Scholar, 3Wenzel A. Williams S. Ritzau M. Relationships of change in craniofacial morphology, head posture, and nasopharyngeal airway size following mandibular osteotomy.Am J Orthod Orthop. 1989; 96: 138-143Abstract Full Text PDF PubMed Scopus (41) Google Scholar, 4Athanasiou A.E. Toutountzakis N. Mavreas D. Ritzau M. Wenzel A. Alterations of hyoid bone position and pharyngeal depth and their relationship after surgical correction of mandibular prognathism.Am J Orthod Dentofacial Orthop. 1991; 100: 259-265Abstract Full Text PDF PubMed Scopus (87) Google Scholar, 5Gu G. Gu G. Nagata J. Suto M. Anraku Y. Nakamura K. et al.Hyoid position, pharyngeal airway and head posture in relation to relapse after the mandibular set back in skeletal Class III.Clin Orthod Res. 2000; 3: 67-77Crossref Scopus (60) Google Scholar, 6Cho D. Choi D.S. Jang I. Cha B.K. Changes in natural head position after orthognathic surgery in skeletal Class III patients.Am J Orthod Dentofacial Orthop. 2015; 147: 747-754Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar It is well established that Class II patients have a reduced oropharyngeal airway compared with Class III patients, with Class I being intermediate.7Trenouth M.J. Airway, Pierre Robin and functional jaw orthopaedics.Cranio. UK. 2019; 10: 12-18Google Scholar Craniocervical angle was found to be on average 10° larger in patients with obstructive sleep apnea,8Solow B. Sandham A. Cranio-cervical posture; a factor in the development and function of the dentofacial structures.Eur J Orthod. 2002; 24: 447-456Crossref PubMed Scopus (142) Google Scholar who incidentally also have reduced oropharyngeal airway dimensions. Treatment with the Twin-block appliance has been shown to increase the width of the oropharyngeal airway,1Trenouth M.J. Desmond S.R. A cephalometric evaluation of oropharyngeal airway changes during Twin-block appliance treatment.Int J Dent Oral Sci. 2016; S4004: 22-30Google Scholar, 9Jena A.K. Singh S.P. Utreja A.K. Effectiveness of Twin-block and Mandibular Protraction Appliance-IV in the improvement of pharyngeal airway passage dimensions in Class II malocclusion subjects with a retrognathic mandible.Angle Orthod. 2013; 83: 728-734Crossref PubMed Scopus (36) Google Scholar, 10Ghodke S. Utreja A.K. Singh S.P. Jena A.K. Effects of Twin-block appliance on the anatomy of pharyngeal airway passage (PAP) in Class II malocclusion subjects.Prog Orthod. 2014; 15: 68Crossref PubMed Scopus (31) Google Scholar which may well account for the change in craniocervical posture. Thus, once an adequate airway has been established, it is no longer necessary for the patient to compensate for an inadequate airway by cervical hyperflexion, and they revert to their normal posture. Evaluation of cervical spine posture after functional therapy with twin-block appliances: A retrospective cohort studyAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 155Issue 5PreviewIt has been postulated that a change in cervical posture occurs as a consequence of forward repositioning of the mandible. Therefore, the objective of this study was to compare the cervical spine posture between subjects with and without functional appliance therapy. Full-Text PDF Authors' responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 156Issue 4PreviewThank you for your keen interest in our article (Kamal AT, Fida M. Evaluation of cervical spine posture after functional therapy with twin-block appliances: A retrospective cohort study. Am J Orthod Dentofacial Orthop 2019;155:656-61). Full-Text PDF