Effect of Manufacturing Technique on the Accuracy of Surgical Guides for Static Computer-Aided Implant Surgery

Purpose: This study aimed to evaluate the effect of different surgical guide manufacturing techniques on the accuracy of the surgical guides produced prior to implant placement. Materials and Methods: Three type of guides were compared: milled guides using a commercial milling unit (C-Mill), printed guides using a commercial 3D printer (C-Print), and printed guides using a benchtop printer (B-Print). All the guides were fabricated on a single maxillary model for anterior implant and posterior implant placement. Ten guides were produced for each group. Four accuracy variables were measured: (1) internal accuracy, (2) vertical fit, (3) guide seating distortion, and (4) drilling access horizontal and vertical deviations. All the variables were virtually measured by 3D rendering software. The Kruskal-Wallis and the Mann-Whitney U tests were conducted to evaluate the significance of the differences among the guide groups. Results: The C-Mill guides were significantly more accurate than the other guide groups for all the accuracy variables (P .05). The C-Print group tended to show greater accuracy than the B-Print group, except for guide seating distortion and horizontal deviation of drilling access. However, a significant difference between the C-Print and B-Print groups was observed only for the vertical deviation of the posterior drilling access (P .05). The location of the implant seemed to have minimal influence on the drilling access accuracy, except for the vertical deviations of C-Mill and C-Print guides, where the anterior site was associated with significantly (P .05) greater errors than the posterior site. Conclusion: Producing guides by milling was more accurate and less vulnerable to seating distortion in comparison to printing. Despite the overall similarity between the two printers, the commercial printer tended to produce guides with greater accuracy than the benchtop printer. Keywords: 3D printing, additive manufacturing, distortion, drilling, milling