Effects of a titratable oral appliance on supine airway size in awake non-apneic individuals

Study objectives: To define morphological changes in the upper airway and its surrounding structures after the insertion of a titratable mandibular repositioner. Design: Ten non-apneic adult males participated in this study A set of supine lateral cephalograms was taken for each subject at the end of expiration with a titratable oral appliance in place in four mandibular positions: most retruded (RP), maximum protrusion (MAX), 33% of MAX (MAX(33)), and 67% of MAX (MAX(67)). Changes in the anteroposterior width of the upper airway, positions of the hyoid bone and the third cervical vertebra were compared between the four mandibular positions. An ANOVA was used to test for statistical significance. Setting: N/A Patients or Participants: N/A Interventions: N/A Measurements and Results: The anteroposterior width of the velopharynx significantly increased when the mandible was advanced from RP to MAX(67) and MAX. However, there were no significant changes in the anteroposterior width of the oropharynx. Significant forward displacement of the hyoid bone and third cervical vertebra together with the mandible was found in MAX(67) and MAX compared to RP. Conclusion: Especially in MAX(67) and MAX, the titratable oral appliance significantly enlarges upper airway size in the velopharynx and results in a forward displacement of the hyoid bone and the third cervical vertebra.