Stability After Bilateral Sagittal Split Osteotomy Advancement Surgery With Rigid Internal Fixation: A Systematic Review

Three-dimensional changes in pharyngeal airway in skeletal class III patients undergoing orthognathic surgery

PURPOSE

It has often been hypothesized that mandibular setback surgery causes narrowing of the pharyngeal airway. We examined whether the pharyngeal airway narrowed after orthognathic surgery in patients undergoing either mandibular setback surgery or bimaxillary surgery and whether the amount of narrowing of the pharyngeal airway was any different after mandibular setback surgery or bimaxillary surgery.

MATERIALS AND METHODS

Cone-beam computed tomography scans were obtained for 21 patients who were assigned to either mandibular setback surgery or bimaxillary surgery. The anteroposterior dimension, lateral width, cross-sectional area, and volume of each subject's pharyngeal airway were measured before and after surgery.

RESULTS

The pharyngeal airway showed significant narrowing after both mandibular setback surgery and bimaxillary surgery. The amount of change in the anteroposterior dimension and cross-sectional area on the posterior nasal spine plane and the length of the pharyngeal airway showed significant differences between the 2 groups.

CONCLUSION

The amount of narrowing of the pharyngeal airway was smaller in patients undergoing bimaxillary surgery than in the patients undergoing mandibular setback surgery.

Hybrid fixation in the bilateral sagittal split osteotomy for lower jaw advancement

Miniplate and screw fixation has been widely used in bilateral sagittal split osteotomy, but some issues remain unclear concerning its lack of rigidity when compared to Spiessl's bicortical technique. This paper demonstrates the hybrid fixation technique in a case report. A 34-year-old female patient underwent a double jaw surgery with counter-clockwise rotation of the mandible fixed using the hybrid fixation technique. The patient evolved well in the postoperative period and is still under follow up after 14 months, reporting satisfaction with the results and no significant deviation from the treatment plan up to now. No damage to tooth roots was done, maxillomandibular range of motion was within normality and regression of the inferior alveolar nerve paresthesia was observed bilaterally. The hybrid mandibular fixation is clearly visible in the panoramic and cephalometric control radiographs. It seems that the hybrid fixation can sum the advantages of both monocortical and bicortical techniques in lower jaw advancement, increasing fixation stability without significant damage to the mandibular articulation and the inferior alveolar nerve. A statistical investigation seems necessary to prove its efficacy.

Biomechanical evaluation of a T-shaped miniplate fixation of a modified sagittal split ramus osteotomy with buccal step, a new technique for mandibular orthognathic surgery

OBJECTIVE

The purpose of this study was to biomechanically evaluate the stability of a T-shaped miniplate fixation of a modified sagittal split ramus osteotomy (MSSRO) with buccal step and to compare it with single or double-parallel straight miniplates fixing a standard sagittal split ramus osteotomy (SSRO).

STUDY DESIGN

Eighteen Synbone mandibular replicas were used in the study and divided into 3 groups. Standard SSRO was applied in the first and second groups, and the third group was cut for MSSRO with buccal step. After 7 mm of advancement, fixation modalities for the 3 groups included a single straight miniplate, double-parallel straight miniplates, and a T-shape miniplate, respectively. Each model was secured in a jig and subjected to vertical load on the anterior teeth.

RESULTS

The T miniplate group showed a significantly higher value for stability than the group with a single straight miniplate. There was no significant difference in stability between the T miniplate and the double-parallel straight miniplate groups.

CONCLUSION

For mandibular advancement surgery of 7 mm in a laboratory environment, a T-shaped miniplate used with MSSRO and buccal step as a combination significantly optimize the resistance and stability of the fixation compared with a standard SSRO fixed with a single straight miniplate.

Long-term stability of adolescent versus adult surgery for treatment of mandibular deficiency

In mandibular deficient patients, mandibular growth is not expected after the adolescent growth spurt, so mandibular advancement surgery is often carried out at 13 years. To test if the long-term stability for younger patients is similar to that for adult patients, the authors compared cephalometric changes from 1-year postsurgery (when changes due to the surgery should be completed) to 5-year follow up. 32 patients who had early mandibular advancement with or without simultaneous maxillary surgery (aged up to 16 for girls and 18 for boys), and 52 patients with similar surgery at older ages were studied. Beyond 1-year postsurgery, the younger patients showed significantly greater change in the horizontal and vertical position of points B and pogonion, the horizontal (but not vertical) position of gonion, and mandibular plane angle. 50% of younger patients had 2-4mm backward movement of Pg and another 25% had >4mm. 15% of older patients had 2-4mm change and none had >4mm. Long-term changes in younger patients who had two-jaw surgery were greater than for mandibular advancement only. Changes in younger groups were greater than for adult groups. Satisfaction with treatment and perception of problems were similar for both groups.