## 2 Materials and Methods  
This study was conducted using the following steps: fabrication of a reference model for the production of the CRM and its digitization using an industrial scanner; the digitization of the reference model using intraoral scanners and laboratory scanners for the production of CTM; and the superimposition and 3D analysis of the CRM and CTM using an inspection software (Figure 1). First, to determine the sample size, a pilot experiment was conducted five times and using a power analysis software (G*Power v3.1.9.2, Heinrich-Heine-Universitat, Dusseldorf, Germany), the number of samples was calculated to be 20 (actual power = 99.2%; power = 99%; \(\alpha\) = 0.05). The results indicated that this study needed at least N = 20 subjects to ensure a power >99%. The actual power achieved with this N (99.20%) is slightly higher than the requested power. A reference model (dental typodont, ANKA-4 V CER, Frasaco GmbH, Tettnang, Germany) was fabricated using dental stone (Type IV, Durone, Dentsply, Catanduva, Brazil). For the reference model, a CRM file was produced using a high-precision industrial 3D scanner with a resolution of 2 \(\times\) 5 Mpx and Blue LED (Solutionix C500, MEDIT, Seoul, Korea). For accuracy, an industrial 3D scanner expert calibrated the equipment prior to performing the CRM scanning. To obtain the CTM of the reference model, five types of intraoral scanners, including CS3500 (Carestream Dental, Atlanta, GA, USA), CS3600 (Carestream Dental, Atlanta, GA, USA), Trios2 (3 Shape, Copenhagen, Denmark), Trios3 (3 Shape, Copenhagen, Denmark), and i500 (MEDIT, Seoul, Korea) and two laboratory scanners, including E1 (3 Shape, Copenhagen, Denmark) and DOF Freedom HD (DOF, Seoul, Korea) were used. Based on the complete arch scan manufacturer's instructions and a review of the literature on the accuracy of various scan strategies, the order of scanning was decided (Figure 2) [3]. In accordance with ISO-12836, each scanner was operated at an ambient temperature of 23 \(\pm\) 2 \({}^{\circ}\)C, and the scanning was performed 20 times by one operator (K.S.) skilled in the use of each of the five types of intraoral scanners. In addition, stereolithography (STL) files were extracted for 3D analysis. The use of various 3D inspection software, each with a different protocol can result in differing results of the 3D analysis [3]. Thus, Geomagic's 3D inspection software (release 2018.0.0, Geomagic control X, 3D Systems, Rock Hill, SC, USA) recommended by ISO-12836 was used in this study [3]. First, for the 3D comparison of each tooth in the analysis program, the CRM file was divided according to each tooth. In addition, to see the distortion of the set of teeth, a plane was created based  
Figure 1: Experimental design. Figure 2: Strategies for complete arch scanning. on a virtual line from the incisor to the half of the second molar tooth in the sagittal plane. After the CRM file was prepared, the CTM file was retrieved and the initial alignment was performed. Also, they were superimposed by the best fit alignment based on all the divided teeth. The sampling rate was set at 100%. The dimensional differences between CRM and CTM were calculated for all data point clouds of the divided teeth. At this time, the data point was calculated with the root mean square (RMS), and the formula is as follows:  
\[RMS=\frac{1}{\sqrt{n}}.\sqrt{\sum_{i=1}^{n}(X_{1,i}-X_{2,i})^{2}}. \tag{1}\]  
where X\({}_{1,i}\) is the measurement point of \(i\) of the CRM, X\({}_{2,i}\) is the measurement point of \(i\) of the CTM, and \(n\) is the number of all points measured in each analysis. The RMS value shows how the deviation between two different sets of data is different from zero. Thus, a low RMS value represents a high degree of 3D conformity of the superimposed data. The 3D comparison was shown as a color difference map, and a range of \(\pm\)1 mm (20 color segments) and a tolerance range of \(\pm\)10 \(\upmu\)m (green) were designated.