Accuracy of Guided Implant Surgery Using Tomographic Guides Combined with Functional Impression: An In Vitro Study

Deviations between virtually planned and placed implants are still reported in guided implant surgery in completely edentulous arches. Associating a functional impression with the tomographic guide may enhance guide retention and reduce deviations. This study evaluated the effect of using a functional impression during tomographic image acquisition on the accuracy of implant placement in the edentulous maxilla.

Fourteen 3D-printed edentulous maxillary models were fabricated. A complete denture was designed and printed for use as a tomographic guide for each model. During dual-scan image acquisition, the experimental group's tomographic guides were seated with a light-body silicone functional impression, whereas the control group was scanned without impression material (n=7). After image registration in Blue Sky Plan software, implants were virtually planned, and surgical guides were printed for the placement of six implants per model. Postoperative scans were obtained, and STL files of planned and placed implants were superimposed to measure linear and angular deviations. Statistical analysis was performed using two-way ANOVA for functional impression and implant region (α=0.05).

No statistically significant differences were found regarding the effects of functional impression or implant position (P>0.05) on apical linear (2.11-3.25 mm), coronal linear (1.41-2.06 mm), or angular deviations (5.82-7.27°).

The accuracy of implant positioning in edentulous maxillae was not significantly affected by the incorporation of a functional impression during tomographic scanning or by the implant region, although deviations were still observed. Further studies are necessary to evaluate the potential benefits of this approach in specific clinical scenarios.