Condylar Position Changes and TMJ Functions After BSSO Mandibular Setback, Low Medial Cut.

Assessment of Condylar Position Changes and TMJ Functions After BSSO Mandibular Setback, Low Medial vs High Medial Cut (Randomized Controlled Trial)

This study hypotheses that using low medial cut osteotomy BSSO in mandibular setback can be an efficient and effective method to limit the bony segment interferences , decreasing muscles stripping during osteotomy ,decrease condylar torque and so securing preoperative condylar position during BSSO in comparison with using high medial cut BSSO.

Research question: Description of research question: P: Population: Patients with facial skeletal deformity and need for mandibular setback using bilateral sagittal split osteotomy (BSSRO) alone or combined with lefort osteotomy. I: Intervention: Patients with facial skeletal deformity and need and for mandibular setback using low medial cut osteotomy as modification of bilateral sagittal split ramus osteotomy (BSSRO). C: Comparator: Patients with facial skeletal deformity and need and for mandibular setback using traditional high medial cut osteotomy bilateral sagittal split ramus osteotomy (BSSRO). O: Outcome: Comparing the post-operative condylar positions changes and TMJ functions of two osteotomies. Research question: Is using low medial cut osteotomy modification in BSSRO in mandibular setback will provide more control over proximal segment position than traditional high medial cut through: limit the segments interference and so maximizes the passive bony contact across the osteotomy site after surgically repositioning the distal segment Passively positioned the proximal segment without displacement of the condyle from its normal position.

mandibular setback using low medial cut ostetomy by keeping the cut ''low'' or close to the mandibular occlusal plane and ''short'' or terminating anterior to the lingula.

mandibular setback by placement of the medial ramus osteotomy cut 'high', just a few millimeters above the lingula, superior and lateral to the entrance point of the inferior alveolar nerve (IAN) into the mandibular foramen ,

assessment of condylar position changes in millimetre using C.T.(axial ,coronal and sagital cut. ). Axial condylar head long-axis angle (AHA): angle between the sagittal plane and the axial condylar head axis line Axial condylar head position (AHP): perpendicular distance between the sagittal plane and the most medial point of the condylar head Frontal condylar head long-axis angle (FHA): angle between the axial plane and the frontal condylar head long-axis line Frontal condylar head position (FHP): perpendicular distance between the axial plane and most superior point of the condylar head Sagittal condylar head long-axis angle (SHA): angle between the coronal plane and the sagittal condylar head long-axis line Sagital condylar head position (SHP): perpendicular distance between the coronal plane and the most superior point of the condylar head

In order to trace the position of the TMJ disc, a line was drawn from the uppermost point of the articular fossa (UAF, marked as 10) to the lowermost point of the articular tubercle (LAT, marked as 0). This line was continued anteriorly and inferiorly. If the anterior border of the disc was anterior to this line, it was considered negative. These two points were chosen because they did not change with remodelling . Perpendicular lines to this line were drawn in the anterior and posterior borders of the disc. Finally, disc position was determined by averaging anterior (point A) and posterior (point P) disc limits.

Inclusion criteria: Age of the patient between (18-60) years Patients in need of mandibular setback using bilateral sagittal split osteotomy. All patients are free from any systemic disease that may affect normal bone healing. Patient with facial deformity will be treated with mandibular setback either mono or bimaxilary surgeries Patient with facial deformity will be treated with mandibular setback either surgery first approach or orthofirst approach. Sufficient dentition to reproduce the occlusal relationships Patient's consent to participate Exclusion criteria: Patients with any systemic disease that may affect normal healing Intra-bony lesions or infections that may interfere with surgery. Previous orthognathic surgeries. Patients with all types of facial clefts