Influence of ZAGA Classification on the Accuracy of 150 Digitally Planned Zygomatic Implants Placement

This 3D analysis assessed the accuracy of zygomatic implant (ZI) placement using a static surgical guide in correlation with ZAGA classification and the rehabilitation type.

Pre-surgical CT scans were used to create a virtual surgical plane, exported as .stl files, and to define the ZAGA classification of each implant. A CT scan was taken 6 months post-surgery, and segmentation of the zygomatic implants was performed. The 3D analysis on 3DSlicer software compared planned and placed zygomatic implants, measuring linear and angular displacements at the apex and base of each model. Displacements were correlated with the ZAGA classification and the type of rehabilitation (if quad, twin, or mono zygomatic implant).

The study included 45 patients and 150 zygomatic implants, all placed using bone-supported surgical guides with no bone modifications. The implant survival rate was 100% at 6 months. Most patients received quad rehabilitation with 4 implants, and there was strong overlap between planned and placed implants. The mean surface displacement was 0.43 mm on the right and 0.45 mm on the left. The angular deviation between the planned and placed implant orientations was lower than 1° for both the anterior and posterior implants. According to ZAGA classification, surface displacement increased from class 0 to 4. No significant differences were found among the type of rehabilitation (p > 0.289).

The study highlights the accuracy of fully guided surgery for zygomatic implant placement, recommending its consideration in clinical decision-making. It also shows greater accuracy in lower ZAGA classes and no significant difference across rehabilitation types.