A novel Snap-FIT implant surgical guide design: proof of principle and pre-clinical evaluation

To evaluate the precision of a novel tooth-supported snap-FIT surgical guide (SF), inspired by the removable dentures clasp principle. Fifteen single missing tooth patients underwent CBCT and optical scans, that were superimposed for implant virtual planning (BlueSkyBio, USA). Two implant surgical guides for each case were designed and 3D printed: classical guide (CG) with the default settings, and a novel SF: offset 0.07 mm, guide thickness 2.3 mm, selective undercuts allowed. Dental models and surgical guides were positioned on the testing stand. The increasing force from 0.1 to 5 N was applied to the metal handle (Straumann, CH), simulating surgery. Guide displacement was captured with an intraoral scanner, scans imported for analysis, and implants placed virtually. Source files and the scanned data were aligned (error: 0.16±0.05 mm). Both surgical guides fitted well to the dental model, with a vertical discrepancy of 0.48±0.59 mm (CG) and 0.49±0.32 mm (SF); p=0.59. Under the force of 1N, virtual implant placement error at the neck was 1.23±0.76 mm vs 0.87±0.27 mm(p<0.05), at the apex 2.35±1.75 mm vs 1.25±0.57 mm(p<0.05) and the angle deviation 6.54±4.08° vs 3.77±3.39°(p<0.05) for CG and SF, respectively. Force of 5N dislodged 6 CG and 1 SF from the dental model and caused handle deviation inside the metal sleeve of 4.09±2,46° vs 3.56±1.68°(p=0.34). The novel SF surgical guide is attainable with a simple modification of classical guide design, without requiring additional materials, devices or procedures. It demonstrates the potential for a considerable increase in implant placement accuracy. Clinical trials are needed to assess SF's clinical feasibility in implant dentistry.