## 2 Technique  
The process was demonstrated in a 25-year-old female patient. 1. A digital impression of both dental arches in occlusion was obtained with a TRIOS 3 color intraoral scanner (3 Shape, Copenhagen, Denmark), and the data were exported as.stl (Standard Triangulation Language) or.ply (Polygon File Format) (Figure 1). 2. A facial scan was acquired using a hybrid LED and infrared light source handheld color 3D scanner (EinScan H, Shining 3D Tech. Co. Ltd., Hangzhou, China). Based on the structured light technology of the LED and invisible infrared light, this scanner makes human face scanning more comfortable without strong light, even turning out to be safe for the patient's eyes [10]. Einscan H technical specifications show an accuracy of up to 0.05 mm and a depth of field of 200-700 mm (Table 1). Figure 1: Digital impression of dental arches in occlusion with intraoral scanner. The patient was seated on a chair 45-50 cm away from the scanner in a room with controlled illumination and was instructed to adopt the same facial expression and same position during the scan. Three different facial scans were acquired using the standard mode setting: the first one in the natural head position with the mouth closed (Figure 2), the second one with a voluntary \"social smile\" (Figure 3), and the last one scanning the face with a lip-and-cheek retractor with dental arches in occlusion (Figure 4). Each facial scan was acquired in less than 10 s. \begin{table}
\begin{tabular}{c c} \hline
**Light Source** & **White Light, Visible—Infrared Light, Invisible** \\ \hline Safety & LED light (eye-safe)—CLASS 1 (eye-safe) \\ \hline Scan accuracy & Up to 0.05 mm \\ \hline Volumetric accuracy & 0.05 + 0.1 mm/m \\ \hline Scan and align speed & 1,200,000 points/s, 20 frames per second \\ \hline Align modes & Markers alignment, feature alignment, hybrid alignment, texture alignment \\ \hline Working distance & 470 mm \\ \hline Depth of field & 200–1500 mm \\ \hline Maximum FOV & 420 \(\times\) 900 mm \\ \hline Point distance & 0.25–3 mm \\ \hline Color scanning & Yes \\ \hline Output formats & OBj; STL; PLY; P3; 3 MF \\ \hline Certifications & CE, FCC, RHS, WEEE, KC \\ \hline \end{tabular}
\end{table} 
Table 1: Facial scanner technical specifications (Einscan H—Shining 3d—www.einscan.com, accessed on 7 September 2022). Figure 2: Face scan with closed mouth. Figure 4: Face scan using a lip-and-cheek retractor. Figure 3: Face scan with voluntary “social smile”. These data were exported in a.stl or.ply file format. 3. Intraoral and facial scans were imported in Appliance Designer CAD software (3 Shape, Copenhagen, Denmark) and matched together. The face scan with a lip-and-cheek retractor was superimposed with the upper arch using the command \"Align model, surface-3 points\", matching three dental points (the incisal edge of the upper incisor and the first upper premolars) (Figure 5). This software performed one first matching between scans, aligning the corresponding three points of the tooth surfaces, then performed a fine superimposition using the \"best-fit alignment\" between the selected surfaces on the teeth. Then, the face scan with the mouth closed and the scan with a smile were then matched with the scan with a cheek retractor using the same command \"Align model-surface-3 points\", superimposing the surface of the front and the nose using 3 anatomical points (cutaneous glabella and endocanthion of the right and left eyes) (Figures 6 and 7). 4. The face scan with a social smile was then modified using the command \"Modify model\", and the portion of the dentition limited by the upper and lower lip line was removed (Figure 8). 5. It is also possible to superimpose the lateral cephalospor of the patient to the face and dental arches to combine the dental and esthetic features with the cephalometric analysis.