Assessment of the Three-Dimensional Surgical Accuracy and Operative Time of 3D-Printed Versus Milled Patient-Specific Titanium Plates in Le Fort I Osteotomy: A Randomized Clinical Trial

• Background and Clinical Rationale Orthognathic surgeries, specifically Le Fort I osteotomy, requires precise transfer of the virtual surgical plan to the operative field to achieve predictable functional and facial outcomes. Conventional splint-based fixation techniques may introduce cumulative inaccuracies arising from laboratory fabrication errors, intraoperative handling, and manual plate adaptation. To overcome these limitations, computer-aided design and computer-aided manufacturing (CAD/CAM) workflows allow for the fabrication of patient-specific titanium plates via 3D printing (additive manufacturing) or milling (subtractive manufacturing). While both fabrication methods aim to enhance surgical accuracy and workflow efficiency, direct randomized controlled trial evidence comparing the three-dimensional accuracy and operative performance of 3D-printed versus milled maxillary patient-specific plates remains limited.
• Preoperative Diagnostic Protocol & 3D Virtual Surgical Planning

1. Presurgical Orthodontic & Diagnostic Setup: Participants undergo presurgical orthodontic treatment for dental decompensation to establish a stable occlusion in at least three points. Preoperative diagnostic records include standardized facial and dental photographs along with dental casts obtained from alginate impressions.
2. Image Acquisition & 3D Skull Reconstruction: Computed Tomography (CT) scans are acquired in the natural head position utilizing a Planmeca ProFace imaging machine. Diagnostic dental models are digitized using an optical scanner (Shera operating system 7Series; Dental Wing Inc., Montreal, Quebec, Canada). The digitized dental models will be manipulated using point-based matching iterative closest point (ICP) registration based on anatomical landmarks followed by manual surface-based registration to generate an artifact-free composite 3D skull model.
3. Surgical Simulation & Guide Design: 3D cephalometric analysis of the bony and soft tissue landmarks are conducted using surgical simulation software (Mimics 19.0; Materialise NV, Leuven, Belgium). Virtual Le Fort I osteotomy and mandibular sagittal split osteotomy (SSO) are simulated, adjusting the maxillary segment relative to facial symmetry planes and clinical anthropometric analysis. The cutting guides will be designed on the maxilla to orient the osteotomy and mark reference holes (16 holes with 8 holes on each side) to be used later for the repositioning/ fixation plate, using CAD software (3-matic 11.0; Materialise NV, Leuven, Belgium).
4. CAD/CAM Manufacturing:

Surgical Guides: Exported in stereolithography (STL) file format and printed in white polyamide (PA2200; EOS e-manufacturing solutions, Munich, Germany) via fused deposition modeling (FDM) on an additive CAM machine (FORMIGA P 110 printer; EOS e-manufacturing solutions, Munich, Germany). The guides are cold-sterilized by overnight immersion in 2% glutaraldehyde.

Patient-Specific Osteosynthesis Plates: Designed to fix the maxilla in the desired position making use of the previously established reference holes. The designed plates will be exported in STL file format to be manufactured in grade 5 titanium alloy using either 3D printing or milling according to randomized allocation .

Intraoperative Protocol & Interventions Surgical procedures are performed under general anesthesia then intraoral local anesthetic infiltration along incision line with (lidocaine 2%, 1/100,000 adrenaline) for hemostasis. Access is established via intraoral vestibular maxillary and sagittal split mandibular incisions.