3D printed surgical guides are used for prosthetically-driven oral implant placement. When manufacturing these guides, information regarding suitable printing techniques and materials as well as the necessity for additional, non-printed stock parts such as metal sleeves is scarce. The aim of the investigation was to determine the accuracy of a surgical workflow for oral implant placement using guides manufactured by means of fused deposition modeling (FDM) from a biodegradable and sterilizable biopolymer filament. Furthermore, the potential benefit of metal sleeve inserts should be assessed. A surgical guide was designed for the installation of two implants in the region of the second premolar (SP) and second molar (SM) in a mandibular typodont model. For two additive manufacturing techniques (stereolithography [SLA]: reference group, FDM: observational group) n = 10 surgical guides, with (S) and without (NS) metal sleeves, were used. This resulted in 4 groups of 10 samples each (SLA-S/NS, FDM-S/NS). Target and real implant positions were superimposed and compared using a dedicated software. Sagittal, transversal, and vertical discrepancies at the level of the implant shoulder, apex and regarding the main axis were determined. MANOVA with posthoc Tukey tests were performed for statistical analyses. Placed implants showed sagittal and transversal discrepancies of <1 mm, vertical discrepancies of <0.6 mm, and axial deviations of ≤3°. In the vertical dimension, no differences between the four groups were measured (p ≤ 0.054). In the sagittal dimension, SLA groups showed decreased deviations in the implant shoulder region compared to FDM (p ≤ 0.033), whereas no differences in the transversal dimension between the groups were measured (p ≤ 0.054). The use of metal sleeves did not affect axial, vertical, and sagittal accuracy, but resulted in increased transversal deviations (p = 0.001). Regarding accuracy, biopolymer-based surgical guides manufactured by means of FDM present similar accuracy than SLA. Cytotoxicity tests are necessary to confirm their biocompatibility in the oral environment.

Background : Digital implant planning and guided insertion facilitates prosthetically-driven implant positioning. Nowadays, most guide systems are using photopolymerized 3D printed surgical templates with metal sleeves for drill guidance. However, a cost-effective but accurate alternative might be represented by sleeveless surgical guides made of polylactate. Since absence of wear cannot be secured using sleeveless surgical guides, this biodegradable material could be beneficial.Aim/Hypothesis : To determine the accuracy of the implant position installed with surgical guides obtained by Fused Deposition Modeling (FDM) or Stereolithography (SLA). Moreover, a potential benefit of inserted metal sleeves and the influence of the implantation site was evaluated.Material and Methods : A surgical guide for the insertion of two titanium implants in a lower jaw resin model in the region of the second premolar and molar was virtually designed with (S) and without (NS) metal sleeves. Each dataset was 3D printed ( n = 10) using SLA and FDM technologies, resulting in four groups (SLA-S, SLA-NS, FDM-S, FDM-NS). Finally, a total of 80 two-piece titanium implants were inserted in the resin model. Scan bodies were used for the digitization by means of a desktop scanner. Discrepancies between the final and virtually planned implant position were measured using an inspection software. Horizontal and vertical deviations at apex and shoulder level, as well as main axis deviations were calculated. For the statistical analysis one-way ANOVA with post-hoc Tukey tests was used.Results : Inserted implants showed maximum horizontal deviation values of 0.97 mm at the implant tip and 0.55 mm at the implant shoulder.(Fig. 1) Furthermore, maximum deviations in the vertical dimension of 0.56 mm at the implant tip and 0.24 mm at the implant shoulder were measured. The implants maximum deviation to the main axis was 3.02°. When comparing the four evaluated groups (SLA-S, SLA-NS, FDM-S, FDM-NS), no statistically significant differences regarding to the implant site were found ( P > 0.05). Likewise, insertion of a metal sleeve had no significant impact on accuracy ( P > 0.05). Pairwise comparisons regarding the manufacturing technology (SLA FDM) showed significant differences between FDM-S and SLA-S ( P = 0.023) for the lateral deviations at apex. Conclusion and Clinical Implications: Within the limitations of the present laboratory setup, all installed implants showed a maximal deviation <1 mm and might be therefore considered suitable for clinical use. Both evaluated 3D printing technologies showed similar outcomes irrespective of the region in the jaw model and the use of metal sleeves does not improve the accuracy of the implantation procedure.

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