## 2 Materials and Methods
### Statistical Analysis  
Intra-examiner reliability was completed to check whether the first investigator's measurements were reproducible. After a two-week interval, the same investigator measured a randomly chosen 10 CBCT images twice. Single-measurement, two-way mixed intraclass correlation coefficient (ICC) analyses for consistency were calculated to evaluate the reliability of the measurements [4].  
A power analysis using PASS software v. 23.0.2 (NCCSS, LLC, Kaysville, UT, USA) was performed to estimate the sample size required for this study. To identify a difference in group means using analysis of variance (ANOVA); an effect size of \(\mathrm{f}=0.45\) indicated that 108 participants would be needed to achieve a power greater than 0.90, with an alpha \(=0.05\).  
Data were analyzed using several statistical tests. For between-group comparisons, independent samples \(t\)-tests, ANOVA, Mann-Whitney, and Kruskal-Wallis tests were used. Assumption tests (Shapiro-Wilk) were conducted preliminarily. If the normality assumption failed, \(p\)-values for [PERSON]'s test for unequal sample sizes and failure to meet homogeneity of variances assumption are reported parenthetically, as well as results from the Mann-Whitney (two groups) or Kruskal-Wallis (more than two groups) tests. For independent variables with more than two categories in which the main effect was statistically significant, [PERSON]'s HSD tests were conducted to identify homogeneous subsets.  
Figure 2: Landmarks and measurements in cone-beam computed tomography (CBCT) images. (**A**) Sagittal CBCT image at the greatest anteroposterior condylar head. (**B**) Coronal CBCT image at the greatest mediolateral condylar head. The abbreviations are as follows: AC, anterior condyle; AE, articular eminence; AF, anterior fossa; AH, anterior head; APT, anteroposterior thickness; ArS, articular slope; AS, anterior space; CF, central fossa; CS, central space; LC, lateral condyle; LF, lateral fossa; LH, lateral head; LS, lateral space; MC, medial condyle; MF, medial fossa; MH, medial head; MLT, mediolateral thickness; MS, medial space; PC, posterior condyle; PF, posterior fossa; PH, posterior head; PS, posterior space; SC, superior condyle; SF, superior fossa; SS, superior space; VHF, vertical height of fossa. AS, PS, MS, and LS were drawn at an angle of 90\({}^{\circ}\) from the tangent lines extending from SF and CF, respectively [4; 13].  
For within-group comparisons, repeated measures of ANOVA and Friedman tests were used. The Greenhouse-Geisser adjustment for lack of sphericity is reported if the assumption of sphericity was unmet. The \(p\)-value for the Friedman test is also reported when at least one of the dependent variables failed to meet normality assumptions. Bonferroni corrections were applied to the multiple pairwise comparisons to identify homogeneous subsets.  
The effect size for each test was calculated using either eta-squared or Kendall's W. Eta-squared, calculated for between-groups comparisons, was interpreted as 0.01 = small, 0.06 = medium, 0.14 = large. Kendall's W, used for within-subject comparisons, was interpreted as 0.1-0.3 = small, 0.3-0.5 = medium, \(\geq\)0.5 = large.  
Power was not explicitly calculated for each cell of the dataset. A sample of \(n\) = 30 would have been sufficient to detect a small-to-medium effect size with 80% power, alpha = 0.05, two-tailed. However, we were not able to obtain 30 subjects within each cell.  
Statistical analyses were performed using SPSS ver. 28 software (IBM Corp., Armonk, NY, USA). For all analyses, an alpha of 0.05 (two-tailed) was used as the criterion for statistical significance. If the parametric and nonparametric test significance results differed, the more conservative nonparametric results were interpreted.