Role of computed tomography in the evaluation of orthodontic treatment in adult patients with obstructive sleep apnea syndrome (OSA)

OBJECTIVE: The aim of this study was to investigate pharyngeal size differences between pre- and posttrials of a Mandibular Advancement Device (MAD), using a computed tomography (CT),in the treatment of Obstructive Sleep Apnea (OSA) adult patients.MATERIALS AND METHODS: Eighteen patients with mild to moderate OSA (mean Apnea/Hypopnea Index, AHI, of 16.7) were treated with a MAD to wear at night only. After 3 months of treatment, three-dimensional changes in pharyngeal dimensions were measured on CT images performed with a sixteen detector-row CT scanner (Light Speed Plus; GE Medical Systems). Two consecutive axial sections from the hard palate to the epiglottis were obtained with and without the appliance. Measurements were made of the following airway areas (mm2) and lengths (mm): RF (nasopharynx); ROF (naso-oropharynx); OF (oropharynx); IPF (hypopharynx); SPL (soft palate length); SPT (soft palate thickness); Rgn (retrognation)-hyoid bone; hyoid bone-C2; Rgn-C2; PhL (oropharynx length); pharynx posterior wall thickness at three level. The angle between the hard and the soft palate (APDM) was also calculated.RESULTS: AHI improved significantly (from 16.7 to 11.2) when the appliance was used. Measurements from CT scans showed statistically significant expansion in the naso-oropharynx area (RF p<.014; ROF p<.050), in the Rgn-C2 length (p<.005) and in the angle between the hard and the soft palate (APDM p<.001).CONCLUSIONS: Our findings confirm the effectiveness of MAD in the treatment of patients with mild to moderate OSA. The use of MAD significantly expands the areas of the upper airway lumen most involved in the collapse.