Comparison of Dimensions of the Nasopharynx and Oropharynx Using Different Anatomical References: Is There Equivalence?

To evaluate the equivalence of the volumes obtained using different anatomic references to measure the nasopharynx and oropharynx on cone-beam computed tomography (CBCT) scans. We hypothesized that no variations would be found in the nasopharynx and oropharynx dimensions when measured using different measurement methods. A total of 40 CBCT scans of patients with skeletal Class I (age range, 20 to 50 years) were measured independently by 2 of us. The nasopharynx and oropharynx subregions were volumetrically measured using the adopted limits of 5 different measurement methods (3 for the nasopharynx and 2 for the oropharynx) and InVivoDental software, version 5.4 (Anatomage, San Jose, CA). The minimum area and the minimum area of localization were also evaluated. The intra- and interexaminer concordance for the measurements from the different methods were verified using the interclass correlation coefficient (ICC). The analysis of variance for repeated measures was used to compare the measurements from the 3 nasopharynx methods. The paired t test was used to compare the measurements from the 2 oropharynx methods. The statistical tests were performed at the 5% significance level using SPSS software, version 22.0 (IBM Corp, Armonk, NY). The intra- and interexaminer ICC values were greater than 0.8. We found a statistically significant difference in the volume measurements among the 3 nasopharynx methods (P = .001). However, no differences were found in the minimum area or minimum area of localization comparisons. Statistically significant differences were also observed for the volume, minimum area, and minimum area of localization between the 2 oropharynx methods (P = .001). Studies that have used different methods of measurement should not be directly compared. The different measurement methods used for nasopharynx and oropharynx evaluations should not be compared.