Model surgery
CAIS, Callus, fatigue
CREST
The interventions were performed by a surgeon (M.K.) who was well experienced in the clinical use of static CAIS with both pilot-guided and fully guided protocols. Model surgeries were carried out in a randomized order over the course of five days with three model surgeries (18 implants placed) each day to avoid inaccuracies due to fatigue.Osteotomies were carried out at a drill rotation speed of 800 rpm with external cooling. Dental implants 4.2 mm in diameter and 10 mm in length (article number: CP 1042 − 100, Callus Pro, Callus Implant Solutions GmbH, Nuremberg, Germany) were placed at sites FDI 13, 14, 16, 23, 24, and 26 in all three study groups.In Group 1, the fit of the surgical guide was verified, and the templates were stabilized on the models using three guide fixation pins (article number: 3DM00609, 3DM00671, 3DIEMME, RealGUIDE, Cantù, Como, Italy). A pilot drill with a 2 mm diameter (article number: CP 2mmL, Callus Implant Solutions GmbH, Nuremberg, Germany) was used for the pilot osteotomy. The surgical template was removed, and straight implant drills of 2.3 mm, 2.8 mm, 3.4 mm, and 3.8 mm (article numbers: CP 2.3mmL, CP 2.8mmL, CP 3.4mmL, CP 3.8mmL, Callus Implant Solutions GmbH, Nuremberg, Germany) were used for implant bed preparation. Dental implant placement was performed manually with a ratchet.In Group 2, after checking the fit of the surgical template, stabilization was carried out using three guide fixation pins. A pilot drill with a 2 mm diameter (article number: CP 2mmL, Callus Implant Solutions GmbH, Nuremberg, Germany) was used for the pilot osteotomy. Implant beds were finalized in a free-handed manner according to the manufacturer’s instructions. Step drills of 2.0/2.3 mm, 2.3/2.85 mm, 2.8/3.3 mm, and 3.25/3.7 mm (article numbers: CP CD1, CP CD2, CP CD3, CP CD4, Callus Implant Solutions GmbH, Nuremberg, Germany) were used for osteotomies. Dental implant placement was performed manually with a ratchet.In Group 3, the fit of the template was checked, and fully guided implant bed preparation was carried out according to the instructions of the manufacturer of the fully guided kit (RealGUIDE Full Surgical Kit, RealGUIDE, Cantù, Como, Italy) using the following drill sequence: bone crest leveller (article number: 3DM00614), start drill, (article number: 3DM00621), drill D1.6 × 7 mm (article number: 3DM00613.16.70), drill D2.3 × 8.5 mm (article number: 3DM00613.23.85), drill D2.3 × 10 mm (article number: 3DM00613.23.10), drill D3.0 × 10 mm (article number: 3DM00613.30.10), drill D3.4 × 10 mm (article number: 3DM00613.34.10), and drill D3.8 × 10 mm (article number: 3DM00613.38.10). Implant placement was performed using a manual torque wrench (article number: 3DM00611) with the implant mount (Nobel Active RP connection, article number: 3DM00606NBLACTRPL 3DIEMME, RealGUIDE, Cantù, Como, Italy). Figure 
The experimental setup in the three study groups. In Group 1, model surgeries were carried out using pilot-guided sCAIS followed by step drills. In Group 2, implant placement was performed with a pilot-guided protocol followed by straight drills. In Group 3, fully guided sCAIS was performed to place implants. The design of one of the surgical templates used in Groups 1 and 2 (