An interventional study of bimaxillary surgery(Lefort I and SSRO) in CAD/CAM, Patient Specific Implant and Orthognathic Surgery, sponsored by Peking Union Medical College. Recruiting at 1 site in China. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-02.
Sponsored by Peking Union Medical College · Not applicable, Interventional, and Treatment
Dentofacial deformity refers to a group of disorders characterized by malocclusion and facial asymmetry resulting from developmental abnormalities of the maxilla and mandible, which cause morphological and positional anomalies of the jaws. Compared with the traditional orthodontics-orthognathic surgery-orthodontics treatment protocol, the surgery-first approach has witnessed a continuous expansion of its clinical application scope. Nevertheless, academic controversies persist regarding its indication boundaries, postoperative jaw stability, and adaptive changes of the temporomandibular joint.
In orthognathic surgery, computer-aided design/computer-aided manufacturing (CAD/CAM) surgical guides indirectly determine the three-dimensional spatial positions of the maxilla and mandible through occlusal relationships. The tooth-bone dual-supported osteotomy and positioning guide combined with pre-bent patient-specific implants (PSIs) forms a novel surgical guide system that enables independent and direct positioning of the maxilla. Theoretically, this system can eliminate errors derived from mandibular positional instability and thereby improve surgical accuracy. However, comparative studies investigating the clinical application of these two types of guides in surgery-first orthognathic surgery are still lacking.
This prospective, randomized, controlled, single-blind clinical study aimed to explore the clinical value of PSIs and conventional CAD/CAM guides in surgery-first orthognathic surgery, with primary outcomes focusing on surgical accuracy, postoperative jaw stability, and temporomandibular joint alterations. The findings will provide evidence-based medical support for the expanded application of this novel technique in precision orthognathic surgery.
Peking Union Medical College is the lead sponsor of 58 studies on the registry; 17 are open to participants now.
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Exclusion Criteria:
Tooth-bone borne osteotomy and repositioning guides combined with patient-specific implants constitute the PSI group for short. Preoperative craniomaxillofacial computed tomography (CT) data of patients were imported for three-dimensional reconstruction. Surgical plans, including genioplasty procedures, were collaboratively formulated by surgeons and orthodontists with full consideration of patients' personal preferences. Custom tooth-bone dual-supported osteotomy and positioning guides for both the maxilla and mandible were digitally designed and subsequently fabricated. A partial skull model was printed preoperatively, on which custom titanium plates were pre-bent in advance in strict accordance with the established surgical protocol.
Procedure: bimaxillary surgery(Lefort I and SSRO)
Patients' preoperative craniomaxillofacial computed tomography (CT) data were imported for three-dimensional (3D) reconstruction. Surgeons and orthodontists collaboratively formulated individualized surgical plans based on patients' preferences, including genioplasty procedures, followed by the design and fabrication of CAD/CAM intermediate and final surgical guides.
Procedure: bimaxillary surgery(Lefort I and SSRO)
All patients underwent surgery-first bimaxillary orthognathic surgery, with concomitant optional procedures including maxillary and mandibular subapical osteotomy and genioplasty.
Linear deviation
Following the superimposition of preoperative virtual surgical planning models and postoperative actual craniomaxillofacial computed tomography (CT) datasets, manual registration was performed based on anatomical landmarks including the nasion, foramen magnum, infraorbital point, zygomatic bone, and zygomatic arch. Linear deviations of the A-point, B-point, canine teeth, and first molars relative to the Frankfort horizontal plane, facial midsagittal plane, and coronal plane were measured and recorded.
Time frame: 7 days and 1 year
Angular deviation
Following the superimposition of preoperative virtual surgical planning models and postoperative actual craniomaxillofacial computed tomography (CT) datasets, manual registration was performed based on anatomical landmarks including the nasion, foramen magnum, infraorbital point, zygomatic bone, and zygomatic arch. Angular deviations of the A-point, B-point, canine teeth, and first molars relative to the Frankfort horizontal plane, facial midsagittal plane, and coronal plane were measured and recorded.
Time frame: 7 days and 1 year
Soft tissue change
Soft tissue changes were evaluated based on three-dimensional facial scan data acquired using a 3dMD system. Following the superimposition of preoperative virtual surgical planning models and postoperative actual facial scan datasets, changes in soft tissue landmarks were assessed, including the nasal base, lips, nose, etc.
Time frame: 1 year
satisfatory questionnaire
Time frame: 1 year
Plan to share: Yes — Raw data of linear/angular deviation, soft tissue change, and questionnaire
Supporting information: Study protocol
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Peking Union Medical College