Evaluation of the posterior airway space following orthopaedic treatment of mandibular deficient Class II malocclusion - a pilot study

Abstract

Background: The use of Twin Block therapy is a well-accepted functional treatment option for the correction of a Class II malocclusion. In addition to skeletal and dental changes, its use may also promote changes in airway structure and dimension, including the size of the posterior airway space (PAS). This may be of importance in reducing the risk of developing obstructive sleep apnoea syndrome (OSAS). Materials and methods: Sixteen (16) subjects (eight females and eight males) underwent treatment of a Class II division 1 malocclusion via the use of a Sydney Bonded Twin Block (SBTB) appliance followed by full fixed orthodontic therapy (FFOA). Pretreatment (T1), post-twin block (T2) and post-fixed appliance (T3) lateral cephalograms were taken and skeletal and soft tissue landmarks were hand traced. A pairwise comparison was used to assess whether there were any significant differences in the cephalometric variables between each phase of treatment (T1, T2, T3). Results: The skeletal variables SNB and ANB revealed a significant change between T1-T2 (p < 0.01). The sagittal size of the nasopharynx (RPAS) also recorded a significant change between T1-T3 (p < 0.05). There was no significant change in the PAS at any stage of treatment. There was an average reduction in the ANB angle of 2° (p < 0.01) between T1-T3. Conclusions: There was no significant change in the size of the PAS following SBTB treatment. However, an increase in RPAS was recorded following SBTB treatment which continued to improve during FFOA therapy.