## 2 Materials and Methods
DICOM files were processed using Mimics Software (version 10.11, Materialise Medical Co, Leuven, Belgium) and exported in IGES format for both right and left sides. For each CBCT image, skeletal and dental landmarks were taken using a coordinate system previously proposed in a similar study [17]. ELSA (midpoint of line connecting both foramen spinosum landmarks) was set as x, y, and z origin and corresponding coordinate planes (x: coronal; y; sagittal; z: axial) that started from ELSA point passing through RPo (Right auditory external meatus) and LPo (Left auditory external meatus) points was constructed. Table 1 summarizes the landmark's definition and their identification. Figure 1: Flow diagram of patient selection according to consort statement. \begin{table}
\begin{tabular}{c c} \hline \hline
**Cranial References** & \\ \hline Foramen spinosum (**RFs, LFs**) & Geometric center of the upper and smallest circumference with defined borders viewed axially on the foramen spinosum. \\ \hline
**ELSA** & Midpoint on a line connecting left and right foramen spinosum landmarks. \\ \hline
**Auditory External Meatus (**RPo, LPo**) & Most upper, posterior and lateral point of Auditory External Meatus circumference with defined borders viewed saggitally. \\ \hline
**Skeletal landmarks**  
From IGES data on the three planes, the following calculation was subsequently applied to obtain bilateral linear measurements  
\[\sqrt{\left(\mathbf{x}^{(1)}-\mathbf{x}^{(2)}\right)^{2}+\left(\mathbf{y}^{(1)}-\mathbf{y}^{(2)} \right)^{2}+\left(\mathbf{z}^{(1)}-\mathbf{z}^{(2)}\right)^{2}}\]  
All calculated measurements of skeletal and dental landmarks are described in Table 2.  
The IBM SPSS software, v.22.0 (IBM Corp., Armonk, NY, USA) was employed to perform statistical analysis. Shapiro-Wilk test revealed a normal distribution of the data and, therefore, parametric tests were employed for statistical analysis. Student t-test was used to compare groups. A paired sample t-test was used to compare each variable within the same group, between T0 and T1; independent t-test was used to compare each variable between groups, with a 5% of significance. All measurements were previously performed 3 times on 10 randomly selected patients to evaluate measurement error in x, y, and z directions (Table 3). Statistical analyses were performed considering the mean of the three measurements. Casual and systematic errors were calculated comparing the first and second measurements with [PERSON]'s formula and dependent \(t\)-test, respectively, at a significance level of 5%. The mean error and 95% confidence interval among the repeated data were 0.6 mm (0.5-0.7); reliability coefficient ranged from 95% to 97%. \begin{table}
\begin{tabular}{c c} \hline \hline
**Cranial References** & \\ \hline Dental landmarks & \\ Pulp chamber (**PC tooth \#**) & Center of pulp chamber floor viewed in \\  & all 3 planes of space. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._ \begin{table}
\begin{tabular}{c c} \hline \hline
**Skeletal Landmarks** & \\ \hline Nasal Floor width (**NF**) & Distance between **RNF** and **LNF** points \\ Pterygoid width (**LPt**) & Distance between **RLPt** and **LLPt** points \\ \hline \hline \begin{tabular}{c} Dental landmarks \\ \end{tabular} & \begin{tabular}{c} Datalog \\ \end{tabular} & \
\begin{tabular}{c} Datalog between 1.6 and 2.6 **PC** points \\ \end{tabular} \\ Upper second primary molar distance (**E + E**) & Distance between 5.5 and 6.5 **PC** points \\
\begin{tabular}{c} Furca distance (**FURCA**) \\ \end{tabular} & Distance between 1.6 and 2.6 **Furca** points \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Skeletal and dental linear measurements and their definition.