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: 1. limit the segments interference and so maximizes the passive bony contact across the osteotomy site after surgically repositioning the distal segment 2. Passively positioned the proximal segment without displacement of the condyle from its normal position.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
24
mandibular setback using BSSRO
Faculty of Dentistry Cairo University
Cairo, Egypt
3D mandibular condylar position changes
assessment of condylar position changes in millimetre using C.T.(axial ,coronal and sagital cut. ). 1. Axial condylar head long-axis angle (AHA): angle between the sagittal plane and the axial condylar head axis line 2. Axial condylar head position (AHP): perpendicular distance between the sagittal plane and the most medial point of the condylar head 3. Frontal condylar head long-axis angle (FHA): angle between the axial plane and the frontal condylar head long-axis line 4. Frontal condylar head position (FHP): perpendicular distance between the axial plane and most superior point of the condylar head 5. Sagittal condylar head long-axis angle (SHA): angle between the coronal plane and the sagittal condylar head long-axis line 6. Sagital condylar head position (SHP): perpendicular distance between the coronal plane and the most superior point of the condylar head
Time frame: Preoperative- 1-month postoperative - 6 months post operative
Assessment of changes in articular disc position
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.
Time frame: Preoperative , 6month postoperative
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