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Updated: May 8, 2026
Real-Time Dynamic Navigation System for the Precise Quad-Zygomatic Implant Placement in a Patient with a Severely Atrophic Maxilla
Published on: October 18, 2021
Three-Dimensional Evaluation of Zygomaticomaxillary Complex Displacement and Rotational Centre in Adults Induced by
Lingling Hu1, Ning Chang2, Zhijian Xie1
1Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Zhejiang Provincial Clinical Research Center for Oral Diseases, Zhejiang Key Laboratory of Oral Biomedical, Zhejiang-Singapore International Joint Laboratory of Oral Bioengineering, Hangzhou, Zhejiang, China.
Objective:
To precisely identify the three-dimensional (3D) centre of rotation (CoR) of the zygomaticomaxillary complex (ZMC) in patients undergoing rapid palatal expansion with a maxillary skeletal expander (MSE) using a heuristic search algorithm.
Materials And Methods:
In this retrospective study, 17 adult patients (mean age 24.0 ± 6.0 years) with maxillary constriction were treated with MSE. Cone-beam computed tomography (CBCT) scans were acquired before treatment (T0) and after the active expansion phase (T1). A heuristic search algorithm was applied to 3D reconstructed models to iteratively compute the patient-specific CoR by minimising the error between predicted and actual displacements of 10 ZMC landmarks. A 95% 3D confidence ellipsoid analysis was performed to quantify the spatial distribution and variability of CoRs. Landmark displacements were statistically analysed using paired t-test.
Results:
Significant lateral, anterior and inferior displacements were observed in all ZMC landmarks following MSE expansion. The algorithm identified the CoR for each side not as a fixed anatomical point but as a confined 3D region with individual variability. After standardisation, the CoR was consistently located biomechanically near the superior orbital fissure, approximately aligned with the orbital longitudinal axis in the coronal plane. The 95% confidence ellipsoid further confirmed the regional distribution and side-related differences in CoR variability.
Conclusions:
During MSE expansion, the ZMC undergoes complex 3D rotational movement around a patient-specific yet spatially consistent biomechanical region near the superior orbital fissure. This updated understanding of midfacial biomechanics may support more personalised and mechanics-guided orthodontic treatment planning.
Trial Registration:
ClinicalTrials.gov identifier: MR-33-25-072630.
