The morphological relationship between upper airway and chin in ClassI malocclusion

Objective To investigate the morphological relationship between the upper airway and chin by cone-beam computed tomography (CBCT) , and explore the effect of chin on the morphology of upper airway. Methods All 18 adults with skeletal ClassⅠ malocclusion in Department of Orthodontics, Dalian Stomatology Hospital were chosen from 2017 to 2018. MIMICS 20.0 software was used to measure the upper airway morphology and Winceph 8.0 software was used to measure the chin morphology. SPSS 20.0 was used for statistical analysis, and a value of P<0.05 was considered statistically different. Results The length of the glossopharynx was positively correlated with the front chin thickness and protrusion (rfront chin thickness = 0.573, Pfront chin thickness = 0.013; rchin protrusion = 0.647, Pchin protrusion = 0.004) , and negatively correlated with chin angle (r = -0.476, P = 0.046) . The transverse diameter of the glossopharynx was positively correlated with the front chin thickness and protrusion (rfront chin thickness = 0.477, Pfront chin thickness = 0.045; rchin protrusion = 0.559, Pchin protrusion = 0.016) . The volume of the glossopharynx was positively correlated with the front chin thickness and protrusion (rfront chin thickness = 0.496, Pfront chin thickness = 0.036; rchin protrusion = 0.681, Pchin protrusion = 0.002) , and negatively correlated with chin angle (r = -0.556, P = 0.017) . The total height and volume were positively correlated with the chin protrusion (rtotal height = 0.531, Ptotal height = 0.005; rtotal volume = 0.469, Ptotal volume = 0.023) . Conclusion The more protrusion of the chin, the more enlarged glossopharynx in ClassⅠ malocclusion. Key words: Malocclusion; Chin; Upper airway morphology; Skeletal ClassⅠ