A Study Of Relationship Between Maxillofacial Skeletal Morphology And Oropharyngeal Airway And Hyoid Position

Objective: To examine differences in oropharyngeal airway dimensions and hyoid position between adolescents with a normal maxilla and mandible and those with a normal maxilla and mandibular retrognathism,and to investigate relationship between oropharyngeal airway dimensions and the mandible and hyoid position in these adolescents.Methods: In total,226 skeletal Class I(0.7°≤ANB<4.7°)or Class II(ANB ≥4.7°)adolescent patients were examined and categorized into two groups: normal group and retrognathic group.Group classifications were made based on SNA angle(angle formed by sella-nasion-subspinale),SNB angle(angle formed by sella-nasion-supramental),ANB angle(angle formed by subspinale-nasion-supramental),and maxillary length(Ptm-ANS).From the total available cases,60 subjects met the above classification criteria and had a normo-divergent facial pattern,with 30 cases in each group.Cone beam computed tomography(CBCT)images were collected for each participant and InVivoDental(Anatomage,San Jose,Calif)software was used to analyze 60 CBCT scans.Mimics 17.0 software was used to reconstruct the oropharyngeal airway,and indices of oropharyngeal airway dimensions,the mandible,and hyoid position were calculated.The statistics of the variables were analyzed using t-tests and Pearson correlation.Results: The normal and mandibular retrognathism group have significant differences in oropharyngeal volumes and hyoid position.With decreases in mandibular length and SNB angle,oropharyngeal space volume tended to decrease,the hyoid tended to be more superior and posterior.Conclusion: Oropharyngeal airway dimensions of adolescents who have mandibular retrognathism are significantly narrower than that of the normal adolescents.There are significant correlations between the oropharyngeal space and both the mandible and hyoid position.