Orthodontics, upper airways and sleep apnea

Obstructive Sleep Apnea (OSA) is becoming a recognized public health problem due to the increasing levels of knowledge within the scientific community regarding its aetiology and contributing factors. Several orthodontic interventions including Rapid Maxillary Expansion (RME) have been shown to impart favourable changes in the anatomic dimensions of the upper airways; however, the evidence is of low quality due to retrospective studies of problematic study design, with small samples, incomplete reporting and high risk of bias. Subsequently, a randomized clinical trial was designed and conducted showing that tooth-borne and hybrid expander improved the volumes of the upper airway and its compartments while amongst them no significant differences were observed, even though there was a constant trend of the hybrid-expander to perform slightly better compared to the other 2 tooth-borne expanders. Similar improvements were noted in the pressures and velocity of airflow within the nasal cavity. The distribution of electronic questionnaires to laypeople for assessing the level of knowledge regarding the signs and symptom of OSA on Australian population revealed results similar to those reported in other populations showing that the level of public awareness is low leading to delays in the timely recognition, diagnosis and management of OSA. Additionally, systematic evaluation and meta-analysis showed that different anteroposterior (sagittal) and vertical craniofacial pattens impact airway volumes. Class II convex skeletal profiles have reduced volumes compared to normal Class I and concave Class IIIs while the hyperdivergent (vertical) skeletal pattern has also reduced volumes compared to normodivergent and hypodivergent (horizontal) growth patterns. Finally, collection and synthesis of the evidence of randomized clinical trials regarding the effectiveness of non-pharmacological interventions in adults suffering from OSA showed that the greatest improvements in AHI and all-cause mortality were achieved with positive airway pressure (PAP) devices of any type (CPAP, BiPAP etc) with and without other adjunctive procedures such as life-style modifications, exercise, weight loss and cognitive behavioural therapy. These measures were the most effective irrespective to baseline severity of OSA; however, mechanical support of breathing during sleep was not always well tolerated by patients. Other interventions that include orthodontic procedures such as orthognathic surgery and mandibular advancement devices (MADs) were effective; however, the evidence is relatively weak. With the increased interest in personalised medicine, craniofacial assessment of specialist orthodontists could contribute to identifying another possible contributor in the aetiopathogenesis of OSA. Based on OSA severity and existing comorbidities, craniofacial patterns with co-existing malocclusions can be accounted in conjunction to patient needs and preferences and thus the indicated interventions can be discussed and decided within the multidisciplinary team aiming to successful OSA management, which further indicates the need for improvement through educational and healthcare policy measures.