Transfer accuracy of 3D printed versus CAD/CAM milled surgical guides for temporary orthodontic implants: A preclinical micro CT study

Objectives: Temporary anchorage devices (TADs) have become an integral part of comprehensive orthodontic treatments. This study evaluated the transfer accuracy of three-dimensional (3D) printed and computer-aided design/computer-aided manufacturing (CAD/CAM) milled surgical guides for orthodontic TADs using micro- computed tomography (CT) imaging in a preclinical trial. Methods: Overall, 30 surgical guides were used to place TADs into typodonts; 3D printing and CAD/CAM milling were used to produce the guides. The virtual target positions of the TADs were compared to the real positions in terms of spatial and angular deviations using digital superimposition. Micro-CT imaging was used to detect the positions. To evaluate reliability, two investigators collected the measurements twice. Intra-rater and inter-rater correlations were tested. Results: In total, 60 palatal TADs were evaluated. The mean coronal deviations in the print group ranged from 0.15 f 0.20 mm to 0.71 f 0.22 mm, whereas in the mill group, they ranged from 0.09 f 0.15 mm to 0.83 f 0.23 mm. At the apical tip, the overall deviations in the print group ranged from 0.14 f 0.56 mm to 1.27 f 0.66 mm, whereas in the mill group, they ranged from 0.15 f 0.57 mm to 1.09 f 0.44 mm. The mean intra-class and interclass correlation coefficients ranged from 0.904 to 0.987. No statistically significant differences were found between the groups. Conclusions: CAD/CAM milled guides yielded spatial and angular accuracies comparable to those of 3D printed guides with notable deviations in the vertical positioning of TADs. Clinical significance: Digital planning of orthodontic temporary implants combines clinical predictability and the safety of surrounding tissue. Therefore, the transfer accuracy of the guides is crucial. This preclinical study was the first to evaluate CAD/CAM milling for orthodontic guides and found its accuracy comparable to that of the current "gold standard".