Analysis of three dimensional oropharyngeal airway and hyoid position in retrognathic adolescent patients

Abstract

Objective

To test the null hypotheses that there is no significant difference in the three-dimensional size of the oropharyngeal space or hyoid position when comparing individuals with a normal jaw relationship with individuals with retrognathic mandibles.

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, SNB angle, ANB angle, 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 upper airway, and indices of oropharyngeal airway dimensions and hyoid position were calculated.

Results

The oropharyngeal airway dimensions of adolescent patients in the retrognathic group were smaller than adolescent patients in the normal group. The hyoid was positioned more superior and posterior in the retrognathic group. With decreases in mandibular length and SNB angle, oropharyngeal space volume tended to decrease, the hyoid tended to be more superior and posterior.

Conclusion

The null hypotheses were rejected. Significant differences in the three-dimensional size of the oropharyngeal space or hyoid position when comparing individuals with a normal jaw relationship with individuals with retrognathic mandibles.