顎変形症患者における咽頭気道形態の三次元ＣＴ評価

Regarding diagnostic imaging for surgical correction of jaw deformities, a three-dimensional evaluation of upper-airway structures composing the airway wall morphology is considered to be essential for predicting post-operational changes in the volume and shape of the airway. The aims of this study were as follows: (1) to propose useful measuring methods for estimating the morphology of the pharyngeal airway, (2) to identify which morphologic factor has the greatest influence on the volume of the pharyngeal airway, and (3) to investigate the relationship between the maxillofacial morphology and pharyngeal airway shape.<br>Pre-operative CT images of seventy-nine patients with jaw deformity aged from 15 to 20 years who were candidates for surgical orthodontic treatment were used in this study. The airway was measured from the nasopharyngeal level to tongue-base level, and the average cross-sectional area was calculated from the volume and length of the airway. To obtain the area, antero-posterior diameter, and width measurements, cross-sections at four levels were selected in the upper airway; i.e., nasopharyngeal level, hard-palate level, oropharyngeal level, and tongue-base level. In order to evaluate the correlation between maxillofacial and pharyngeal morphology, cephalometric analysis was carried out using lateral cephalograms. The subjects were divided into two groups based on skeletal deformities of Class II and Class III from the results of cephalometric analysis, and the differences in pharyngeal morphology between the two groups were investigated statistically. The significance level was set at P < 0.05. The average volume and average cross-sectional area of the pharyngeal airway was 15.71 ± 5.36 cm³ and 2.23 ± 0.74 cm² respectively. Our results revealed that the area at the oropharyngeal level mostly contributed to the size of the pharyngeal airway. It was demonstrated that the area and anteroposterior length at the palatal level in the skeletal Class II group were significantly smaller than those in the skeletal Class III group. Even though no statistical significance was found between the two groups, the width of the airway in the hard-palate level and antero-posterior length in the oropharyngeal level showed a possible statistical correlation with some cephalometric measurement values, indicating that there could be some relationship between airway and maxillofacial morphology.