## 2 Materials and Methods
### Experimental Procedure  
Preoperative CBCT scans of all jaws were obtained with an Orthophos XG 3D CBCT unit (Dentsply Sirona, York, Pennsylvania, USA) with an 8 cm \(\times\) 8 cm field of view and a 0.16-mm voxel size. The parameters were 85 kV, 6 mA, and an exposure time of 14.2 s. Images were stored as Digital Imaging and Communication (DICOM) files. Optical impressions of the teeth were taken using a CARESTREAM CS3600 scanner (Carestream, New York, NY, USA), and data were stored as a stereolithography (STL) file. The datasets obtained from the digital workflow were uploaded to the 3D implant planning software 3 Shape Implant Studio (3 Shape, Copenhagen, Denmark). The software was used to design a virtual template by matching the 3D surface scan and CBCT data while aligning the key points of the crowns of the teeth.  
Virtual implant planning was performed by placing four virtual implants on each side of a pig jaw (STRAUMAN implant diameter 2.5 mm; length 12 mm or 10 mm depending on the situation). The target was the middle of each root at 3 mm above the apex. The virtual implants were inclined at the nearest angle of 80-90 degrees to the dental axis. The surgical guide was designed and fabricated by laser sintering using a 3D printer (Pro X DMP 200 dental, 3D systems, Riom, France; laboratory BONGERT, La Roche sur Yon, France). Depth control was achieved by adjusting the thickness of the guide so that when the surgical drill (length 17 mm, diameter 1.9 mm; ASTRA TECH, Implant System EV) was sunk into the head of the handpiece, it would access 3 mm from the apex of each root with control of the depth to the lingual surface of the root. SMGs were printed in cobalt-chrome, and the design followed current concepts of RPDs to increase stability (Figure 2a-c).  
Figure 1: Workflow diagram of the study design.  
On the night before surgery, the bones were thawed slowly at 4 \({}^{\circ}\)C and then maintained at room temperature. The cheek muscles were retracted to improve visual and instrumental access. Using a sterile no. 15 blade, an intrasulcular incision was extended across 1-2 teeth mesially and distally from the study tooth. This was followed by a vertical release incision mesially. A full-thickness mucoperiosteal flap was then created to expose the bone, and the guides were placed over the occlusal surface of the teeth. Guided osteotomy was performed using a 1.9 mm-diameter, 17 mm-long drill and irrigated with water. The drill speed was 10,000 RPM, and the procedure was performed using a pecking motion until the drill stopped (Figure 3a-d).  
Figure 3: Guided surgery using SMG on pig jaw mandible. (**a**) The adjustment was checked in order to control the stability of the SMG. (**b**) After flap resection, the SMG was placed over the occlusal surface of the teeth. (**c**) The drill was driven through the metal sleeve until it reached the determined stop. (**d**) The final situation shows four drilled paths through the bone.  
Figure 2: Planification of the 3D-printed surgical metal guide. Eight virtual surgical guides were designed using 3D implant planning software 3 Shape Implant Studio. (**a**) Occluso-buccal and (**b**) occluso-lingual views showing one example of the virtual surgical guide in yellow and the optical scan of the mandible pig jaw in blue. (**c**) The different SMGs were 3D-printed in cobalt-chrome.