Dentofacial Deformities, Skeletal Class III Malocclusion, Skeletal Class II Malocclusion
Conditions
Keywords
Orthognathic Surgery, Sagittal Split Osteotomy, Skeletal Class II Malocclusion, Skeletal Class III Malocclusion
Brief summary
This prospective clinical trial aims to evaluate the clinical and radiographic outcomes of the low sagittal medial ramus osteotomy-a technical modification of the conventional sagittal split osteotomy (SSO)-for treating patients with skeletal Class II and Class III malocclusions. Standard sagittal split osteotomies carry risks of complications, including unfavorable osteotomy propagation (bad splits) toward the condyle, ramus fragmentation, lingual interference of the distal segment, and inferior alveolar nerve (IAN) injury. To minimize these risks, this study utilizes a modified medial cut positioned low (below the lingula in an area with adequate marrow space) and short (terminating anterior to the lingula). This design aims to prevent osteotomy extension into the condylar region and eliminate lingual interference during segment repositioning.
Interventions
PROCEDURELow Sagittal Medial Ramus Osteotomy
Patients undergoing orthognathic surgery using the low sagittal medial ramus osteotomy modification. The medial osteotomy cut is initiated slightly above the mandibular occlusal plane, positioned low (below the lingula in an area with adequate marrow space) and short (terminating anterior to the lingula and retrolingual fossa) to achieve 3D mandibular repositioning guided by CAD/CAM virtual surgical planning.
Sponsors
Al-Azhar University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 45 Years
Healthy volunteers
No
Inclusion criteria
* Patients with skeletal Class II or Class III malocclusion requiring mandibular orthognathic surgery. * Age range from 18 to 45 years old. * Systematically healthy patients classified as ASA physical status I or II (American Society of Anesthesiologists)
Exclusion criteria
* Patients with a pre-existing history of inferior alveolar nerve (IAN) sensory impairment. * Patients with active or severe degenerative joint disease (DJD). * Patients with a prior history of orthognathic surgical procedures. * Patients presenting with systemic diseases or conditions known to compromise normal bone healing.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Number of Participants with Unfavorable Osteotomy Split ("Bad Split") | Intraoperative (during the surgical procedure) | Intraoperative evaluation of the occurrence of unfavorable osteotomy propagation (e.g., condylar neck fracture, ramus fragmentation, or buccal/lingual plate fracture) during the sagittal split procedure, assessed via direct visualization and manual palpation. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change from Baseline in Inferior Alveolar Nerve (IAN) Conduction Latency via TSSEP | Baseline (preoperative), 1 month, 3 months, and 6 months postoperatively | Objective electrophysiological assessment of IAN neurosensory function measured using Trigeminal Somatosensory Evoked Potentials (TSSEP). Unit of Measure: Milliseconds (ms) |
| Number of Participants with IAN Entrapment in the Proximal Segment | Intraoperative (during the surgical procedure) | Direct intraoperative visual assessment to report the frequency of the inferior alveolar nerve being contained within the proximal segment versus the distal segment immediately following sagittal splitting |
| Incidence of Distal Segment Lingual Bony Interference | Intraoperative (during the surgical procedure) | intraoperative assessment of lingual bony interference during distal segment positioning into the planned occlusal alignment. Evaluated as a categorical outcome: Presence (bony contact requiring additional osteotomy modification or recontouring to achieve passive seating) vs. Absence (passive seating achieved without bony contact). Unit of Measure: Number of participants |
| Condylar Position within the Glenoid Fossa via Panoramic Radiography | Postoperative Day 7 (within the first week postoperatively) | Postoperative radiographic assessment using panoramic radiographs to confirm anatomical centering and placement of the condyle within the glenoid fossa. Evaluated as Adequate Position vs. Displaced Position |
| Skeletal Stability and Surgical Movement Outcome | 3 months postoperatively | Cephalometric analysis comparing preoperative and postoperative lateral cephalograms to evaluate the gained orthognathic movement and skeletal treatment outcome. |
| Change from Baseline in SNB Angle via Lateral Cephalometry | Baseline (preoperative) and 3 months postoperatively | Radiographic assessment of horizontal mandibular repositioning and skeletal outcome by measuring the change in the SNB angle on lateral cephalometric radiographs. Unit of Measure: Degrees |
| Change from Baseline in Inferior Alveolar Nerve (IAN) Peak Amplitude via TSSEP | Baseline (preoperative), 1 month, 3 months, and 6 months postoperatively | Objective electrophysiological assessment of IAN signal amplitude measured using Trigeminal Somatosensory Evoked Potentials (TSSEP). Unit of Measure: Microvolts |
| Change from Baseline in Linear Pogonion Advancement (Pog-NB Distance) via Lateral Cephalometry | Baseline (preoperative) and 3 months postoperatively. | Radiographic assessment of skeletal advancement and stability measured as the linear distance from Pogonion (Pog) to the NB perpendicular line on lateral cephalometric radiographs. Unit of Measure: Millimeters ($\\text{mm}$) |
| Frequency of Complete Bony Bridging at the Osteotomy Site via 3D CT Scan | 6 months postoperatively. | Radiographic assessment of bone healing across the low sagittal medial ramus osteotomy site evaluated on 3D facial Computed Tomography (CT) scans. Categorized as Complete Healing (continuous cortical/cancellous bone bridging across the osteotomy line) vs. Incomplete Healing (persistent radiolucent gap or non-union). Unit of Measure: Number of participants |
| Presence of Condylar Bony Alterations via 3D CT Scan | 6 months postoperatively | Radiographic evaluation of temporomandibular joint (TMJ) condylar head integrity assessed on 3D facial CT scans. Categorized as Normal (intact condylar surface) vs. Altered (presence of bony remodeling, erosion, or resorption). Unit of Measure: Number of participants |
Outcome results
None listed