Statement of problem. An accurate surgical template for guided implant surgery is essential for the success of an implant restoration. However, reports on the accuracy of digitally designed and computer numeric controlled (CNC) machine-milled surgical templates are sparse. Purpose. The purpose of this in vitro study was to investigate the accuracy of an implant surgical guide digitally designed by using data from cone beam computed tomography (CBCT) scans and milled with a 5-axis CNC machine. Material and methods. Six representative radiographic templates were prepared from radiopaque resin plates. For each guide, a CBCT scan was made, and the extracted Digital Imaging and Communications in Medicine (DICOM) data were imported into a planning software program (ORGANICAL Dental Implant). Nine implants were virtually designed for each guide. The design data were imported into a 5-axis CNC machine, and the radiographic guides were fixed onto the CNC machine (Organical Multi S). Bore holes for surgical guide sleeves were milled directly in the radiographic template, which was converted into a surgical template. After the milling process, the surgical guides were scanned by using a laboratory cast scanner. The deviation between the position of the sleeve bore hole in the milled template and that in the virtual implant planning was digitally calculated. Results. The mean global deviation of the surgical guide was 0.16 +/- 0.06 mm in the circle center of the sleeve top, and the mean angular deviation was 0.61 +/- 0.40 degrees. The sleeve-implant distance and the sleeve axis angle showed no significant influence on the in vitro accuracy of the implant surgical guide. Conclusions. The mean deviation of the surgical guide prepared by using the virtual planning software program and 5-axis CNC milling procedure in this study was 0.16 +/- 0.06 mm in the center of the sleeve top. Thus, the guide had acceptable precision.
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