Accuracy of 3D-printed Surgical Implant Guides

Objectives: This in vitro study aims to evaluate the influence of printing technology, and material on the accuracy of 3D printed surgical implant guides.
Methods: Implant positions were planned preoperatively based on the digital matching of CBCT data sets and STL surface scans using the CoDiagnostix software. Surgical templates were then printed using three different 3D printing devices (Rapidshape D20II, Solflex350 both DLP, Form2 SLA) and six resin materials (3Delta Guide, Freeprint Splint, Fotodent Guide, Nextdent SG, V-print guide) according to manufacturer’s specifications. A total of 132 implants have been randomly assigned to the experimental groups (n=12) for placement into resin clones of a real clinical situation using the various surgical guides. The difference between the virtually designed preoperative and the real postoperative implant position(accuracy) was analyzed considering the horizontal crestal and apical displacement, the angular displacement of the long implant axis and the vertical displacement at implant apex. Surface SEM analysis of selected materials was performed using FE-SEM. Unpaired t-test has been applied for statistical analysis of differences between experimental groups using a level of significance of p<0.05.
Results: Accuracy of implant position was significantly affected by printing technology and resin material (p<0.05) (tab1). The angular displacement ranged from 0.83° (RapidspadeD20II/Freeprint splint) to 2.18° (Form2/NextdentSG), displacement at crest from 0.27mm (RapidspadeD20II/3Delta Guide) to 0.40mm (RapidspadeD20II/Freeprint splint), and at apex form 0.38mm (RapidspadeD20II/NextdentSG) to 0.68mm (Form2/NextdentSG), vertical displacement at apex ranged from 0.09mm (RapidspadeD20II/3Delta Guide) to -0.38mm (RapidspadeD20II/Freeprint splint). Irrespective of the printing device and the resin material the postoperative position of all implants was more crestally than scheduled.
Conclusions: Both, the 3D printing device and the resin material have significant influence on the accuracy of the postoperative implant position. The implant position of all implants was within the commonly accepted three dimensional safety range.