This randomized split-mouth clinical trial aims to compare the accuracy and clinical outcomes of CAD/CAM 3D-printed surgical guides with the conventional free-hand technique for orthodontic miniscrew placement in the posterior maxilla. Each participant will receive miniscrew placement using both techniques on opposite sides of the maxilla following random allocation. The primary outcome is placement accuracy assessed by three-dimensional positional and angular deviations between planned and actual miniscrew positions. Secondary outcomes include miniscrew stability, success rate after three months, postoperative pain, procedural time, patient satisfaction, and complications. The study also evaluates maxillary posterior cortical bone thickness using cone-beam computed tomography (CBCT) and investigates its relationship with miniscrew placement accuracy and stability

Orthodontic miniscrews have become an effective source of temporary skeletal anchorage because they provide absolute anchorage with minimal dependence on patient compliance. However, the success of orthodontic miniscrews largely depends on accurate insertion while avoiding adjacent anatomical structures, particularly dental roots and the maxillary sinus. Incorrect placement may lead to root damage, instability, or failure of the miniscrew Cone-beam computed tomography (CBCT) allows three-dimensional evaluation of alveolar bone morphology and cortical bone thickness before miniscrew insertion. Digital technologies combining CBCT, intraoral scanning, CAD/CAM planning, and three-dimensional printing have enabled fabrication of customized surgical guides designed to improve insertion accuracy This study is designed as a randomized split-mouth controlled clinical trial. Patients requiring bilateral orthodontic miniscrews in the posterior maxilla will receive one miniscrew inserted using a CAD/CAM 3D-printed surgical guide and the contralateral miniscrew inserted using the conventional free-hand technique. The side allocated to each intervention and the order of insertion will be randomized Placement accuracy will be evaluated by superimposing preoperative planning data with postoperative digital models using Geomagic Studio software. Three-dimensional deviations, including coronal and apical positional deviations and angular deviations, will be calculated. Miniscrew stability, success rate after three months, postoperative pain measured by the Visual Analog Scale (VAS), patient satisfaction, operative time, and treatment-related complications will also be evaluated. Additionally, CBCT will be used to measure cortical bone thickness at multiple posterior maxillary interradicular sites, and correlations between cortical bone thickness and miniscrew accuracy and stability will be analyzed

Inclusion Criteria:

• Adults aged 18 years or older.
• Patients requiring bilateral orthodontic miniscrew placement in the posterior maxilla as part of orthodontic treatment.
• Availability of high-quality cone-beam computed tomography (CBCT) images suitable for evaluation and digital planning.
• Good general health and ability to undergo orthodontic treatment.
• Healthy periodontal tissues at the planned miniscrew insertion sites.
• Ability and willingness to provide written informed consent.

Exclusion Criteria:

• Systemic diseases or medications affecting bone healing or bone metabolism.
• Bleeding disorders or contraindications to minor oral surgery.
• Active periodontal disease or local infection at the planned insertion site.
• Poor-quality or incomplete CBCT images.
• Contraindications to CBCT imaging.
• Pregnancy or lactation.
• Previous orthodontic miniscrew placement in the planned insertion area.
• Refusal or inability to provide informed consent.