Accuracy of template-guided zygomatic implant placement: a retrospective case series using cone-beam computed...

To evaluate the three-dimensional accuracy of template-guided zygomatic implant placement using cone-beam computed tomography (CBCT) and to characterize linear, angular, and directional discrepancies between planned and actual implant positions.

This retrospective case series included 14 patients rehabilitated with 21 zygomatic implants using static, bone-supported, stereolithographic surgical guides. Preoperative virtual plans (.stl files) were compared with postoperative CBCT scans through voxel-based registration. The positions of planned (P₁, P₂) and actual (P₃, P₄) implant necks and apices were analyzed to compute vertical (v₃,v₄) and horizontal (h₃, h₄) offsets, angular deviation (θ), and differential parameters describing deviation propagation (Δv = v₄-v₃, Δh = h₄-h₃). A vector-based geometric model was used to separately quantify axial and radial deviations along the implant trajectory. Nonparametric tests were performed (Wilcoxon signed-rank, p < 0.05).

Median deviations were as follows: v₃ = + 0.12 mm, h₃ = 1.18 mm, v₄ = - 0.05 mm, h₄ = 1.98 mm, and θ = 1.05°. The change in offsets revealed Δv = - 0.35 mm and Δh = + 0.81 mm. Horizontal deviations were significantly greater at the apex than at the neck (p = 0.0002), whereas vertical deviations differed significantly between the two implant levels (p = 0.0057). Most implants (≈ 71%) showed a Q₄ pattern (-Δv, +Δh), indicating reduced axial insertion depth associated with increased lateral displacement along the implant axis. Overall, deviations remained below 2 mm and 2°, confirming clinically acceptable precision for prosthetically driven zygomatic implant placement.

Static template-guided zygomatic implant surgery achieved high spatial accuracy with limited angular and linear deviations. The vector-based analysis demonstrated a predominant Q₄ deviation pattern characterized by mild lateral amplification associated with reduced axial insertion depth. Despite higher variability than conventional implant sites, the results support the clinical reliability of static CBCT-based guidance for zygomatic implant rehabilitation.