Description

• 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.

Osteotomy \& Reference Hole Drilling: The maxillary cutting guide is seated on the exposed bone, verified for passive fit, and secured using four 2.0-mm screws. Sixteen reference holes (8 per side) are established through the guide. A reciprocating saw is used to perform the Le Fort I osteotomy, followed by maxillary mobilization and removal of bony interferences. Bilateral sagittal split osteotomies of the mandible are subsequently performed using a mandibular guide.

Fixation Protocol (Randomized Allocation):

Study Arm (Group 1): Maxillary repositioning and fixation are executed using 3D-printed patient-specific titanium plates, aligned with the pre-established reference holes and secured with 2.0-mm screws.

Control Arm (Group 2): Maxillary repositioning and fixation are executed using milled patient-specific titanium plates, aligned with the pre-established reference holes and secured with 2.0-mm screws.

Mandibular Fixation \& Closure: In both arms, the mandible is repositioned and fixated relative to the maxilla using traditional tri-poding bi-cortical screws. Incisions are sutured using 4-0 resorbable sutures in a continuous running fashion.

Postoperative Care \& Evaluation Schedule Postoperative Medications: Systemic antibiotic coverage (Amoxicillin / Clavulanic acid 625 mg every 8 hours) is initiated 4 hours postoperatively and continued for 5 days. Analgesics (NSAIDs every 6 hours) are provided for 3 days, and 0.12% Chlorhexidine mouthwash is prescribed for 2 weeks.

Follow-Up Schedule: Clinical evaluations occur weekly for the first month, followed by monthly visits for 5 additional months.

Radiographic Evaluation \& Orthodontics: A postoperative CT scan is acquired within the first postoperative week using parameters identical to the baseline scan to analyze 3D plan transfer accuracy. Post-surgical orthodontic treatment resumes 4 to 6 weeks postoperatively.

Quality Assurance, Monitoring, and Auditing Supervision \& Governance: All CAD/CAM virtual planning and surgical procedures are conducted under the direct supervision of senior academic staff (Prof. Lobna Abdelaziz Aly and Dr. Aya Magdy AbdelRady) at the Oral and Maxillofacial Surgery Department, Future University in Egypt.

Harms: Any temporary or permanent adverse effect will be recorded and documented.

Auditing: Auditing of the study design will be done by the Research Ethics Council, Future University in Egypt.

Protocol Amendments: Any modifications impacting study conduct, patient safety, or benefits require formal approval by the Council of the Oral and Maxillofacial Surgery Department, Future University in Egypt.

Discontinuation Criteria: Interventions are discontinued if technical difficulty with cutting guides/plates arises or if inaccurate translation of the surgical plan occurs intraoperatively.

Confidentiality: All study-related information will be stored securely. All participant information will be stored in locked file cabinets in areas with limited access. All patients' records will be digitized and stored securely on personal computer.

Ancillary and Post Trial Care: All patients will be followed up until complete healing and satisfactory results occur.

Declaration of interests: The study is self-funded. No conflict of interest Consent: The entire procedure will be explained to the patients and a written consent will be obtained.

Standard Operating Procedures \& Protocol Workflows

1. Patient Recruitment \& Consent:

Inclusion criteria target skeletally mature patients requiring Le Fort I osteotomy for Class II/III malocclusion with good oral hygiene and no active TMDs.

Fully informed written consent is obtained prior to enrollment. 2. CAD/CAM \& Manufacturing:

Preoperative CT scans and digitized dental models. Cutting guides and Patient-specific titanium plates (Grade 5 titanium alloy) are manufactured. 3. Intraoperative Fixation Procedures
4. Postoperative Care \& Follow-Up
5. Adverse Event (Harms) Reporting:

Any temporary or permanent adverse effects occurring during the trial are documented and recorded in patient files.

Plan for Missing Data \& Participant Retention Participant Retention Strategies: Patient phone numbers are recorded during written consent, and structured telephone reminders are made prior to every follow-up visit.

Adherence Verification: Patients are recalled at 1-week intervals and instructed to bring their medication packaging to verify postoperative drug compliance.

Statistical Analysis Plan Statistical analysis will be carried out. Data will be analyzed using IBM SPSS advanced statistics (Statistical Package for Social Sciences), version 21 (SPSS Inc., Chicago, IL). Numerical data will be described as mean and standard deviation or median and range, as appropriate. Because of the small sample size, the comparisons between pre and post treatment will be done by Wilcoxon signed rank test. A p-value less than or equal to 0.05 will be considered statistically significant. All tests will be two tailed.