Clinical Application of Three-Dimensional-Printed Magnetic Connection Digital Guides for Precise Segmental Maxillary Osteotomy

Summary

This protocol describes the digital design, three-dimensional (3D) printing, and intraoperative use of magnetically connected, patient-specific osteotomy guides for a three-segment Le Fort I osteotomy to transfer virtual plans accurately and improve segment alignment.

Abstract

This study introduces the design and clinical application of a novel magnetic-connection digital osteotomy guide to enhance the precision and efficiency of segmental maxillary osteotomy. Segmental Le Fort I osteotomy is an essential technique for correcting complex transverse and vertical dental-maxillofacial deformities, yet traditional methods involving manual plaster model surgery are prone to significant errors. To address these challenges, this protocol integrates virtual surgical planning (VSP) using CT scans and specialized modeling software to create a patient-specific, 3D-printed two-part guide system. The primary component is designed to guide the horizontal Le Fort I osteotomy and bilateral premolar extraction lines. Once the maxilla is down-fractured, a secondary segmental guide is connected to the primary component via four embedded neodymium magnets, each measuring 3 mm in diameter and 1.5 mm in thickness. This magnetic connection provides a stable, rapid, and interference-free attachment that allows for precise guidance of palatal and midline osteotomy lines. This protocol demonstrates the clinical application of a modular magnetic guide system for transferring the virtual osteotomy plan in patients with maxillary protrusion and arch width discrepancies. Postoperative color-map analysis showed local surface deviations of approximately 0.5–0.9 mm around the visible osteotomy margins, supporting the preliminary accuracy of osteotomy-region transfer. The modular magnetic design provides staged osteotomy guidance and may reduce the need for repeated adjustments, unnecessary bone removal, and soft-tissue manipulation, which is consistent with vascular-preserving principles, although segment perfusion was not directly assessed. Neodymium magnets are biocompatible, maintain stability after sterilization, and are cost-effective due to their reusability. Despite the potential fragility of current three-dimensional (3D)-printed resin materials, the magnetic connection digital osteotomy guide offers significant clinical value by bridging the gap between virtual planning and surgical execution. This method ensures highly accurate bone removal and positioning, representing a promising advancement for complex orthognathic surgical procedures.

Introduction

Segmental Le Fort I osteotomy is a well-established surgical method for correcting transverse maxillary discrepancies in skeletally mature patients. In a three-segment Le Fort I osteotomy, the maxilla is first mobilized with a Le Fort I osteotomy and then divided into three segments through interdental and palatal osteotomies. This allows the surgeon to reposition the anterior and posterior maxillary segments according to the planned occlusion and transverse correction. Depending on the planned movement of the maxillary segments, this technique can be used for transverse expansion, correction of asymmetric transverse deformity, or reduction of excessive maxillary arch....

Protocol

This study was approved by the institutional review board of Kunming Medical University (approval No. KYKQ2024MEC0087), and written consent forms were completed by all patients.

1. Preparation before guide design

1. Save the patient’s preoperative computed tomography (CT) data in digital imaging and communications in medicine (DICOM) format.
   NOTE: Use thin-slice CT data whenever possible to provide enough image layers for accurate 3D reconstruction. Poor image quality, large slice thickness, or an insufficient number of slices may reduce the accuracy of the reconstructed maxillary model and affect the ....

Results

Using this workflow, a patient-specific virtual surgical plan and a magnetically connected osteotomy guide system were completed for three-segment Le Fort I osteotomy. Preoperative CT data and dental model scans were integrated to create a composite skeletal-dental model. In the representative case, virtual planning was performed for arch-width reduction in a patient with excessive maxillary arch width. Bilateral first premolar extraction sites were used as the interdental osteotomy regions, and the palatal osteotomy lin.......

Discussion

Three-segment Le Fort I osteotomy is more complex than one-piece Le Fort I osteotomy. In this procedure, the maxilla is not only mobilized but also divided into separate bone segments. After segmentation, each maxillary segment must be repositioned to achieve a stable postoperative occlusion and the planned transverse correction^7,8. Therefore, the accuracy of this procedure depends on two main steps: accurate preoperative planning of the final segment positions a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
3-matic Research 13.0	Materialise	Version 13.0	Used for digital design of the guide components, including cropping, wrapping, marking, undercut removal, inversion, thickening, trimming, and Boolean operations.
Autoscan-DS-EX pro	SHINING 3D	https://www.shining3ddental.com/solution/ds-ex-pro-lab-sacnner/	3D Scanner; Used to scan the upper and lower dental models and the occlusal record
Calibra Universal dual-cure self-adhesive	Dentsply Sirona	https://www.dentsplysirona.com/en-in/discover/discover-by-brand/calibra-cements/calibra-universal.html	Resin cement; For bonding neodymium magnets into the 3D-printed surgical guide.
CT scanner	Siemens Healthineers, Erlangen, Germany	https://www.siemens-healthineers.com/computed-tomography	64-row/128-slice; Used for three-dimensional reconstruction of the craniofacial/maxillary model.
Edge MAX/Edge E2	RAYSHAPE	https://www.rayshape3d.com/3d-printers/edge-e2/	3D printer; Used to print the first and second guide components.
Geomagic Wrap 2021	3D Systems	Version 2021	Used for postoperative model superimposition and color-map deviation analysis.
Mimics Research 21.0	Materialise	Version 21.0	Used for segmentation, three-dimensional reconstruction, and removal of unnecessary structures.
Neodymium magnets	Purchased from Jinyixin Magnetics	https://jingxin-magnet.com/	3 mm diameter × 1.5 mm  thickness; Embedded into the reserved magnet grooves to connect the first and second guide components.
ProPlan CMF	Materialise	Version 3.0.1	Used for virtual orthognathic surgical planning, including Le Fort I osteotomy, BSSRO planning, segmentation, and occlusal registration.
Resin	RAYSHAPE	SGV2/Model 1 lvory	Used to fabricate the intraoperative magnetically connected osteotomy guide components.
ShapeCure	RAYSHAPE	https://www.rayshape3d.com/post-processing/uv-curing-machine-shapecure/	Curing unit