Accuracy of a workflow using sleeveless 3D printed surgical guides made from a cost-effective and biodegradable material: An in vitro study

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.