Phẫu thuật chỉnh hình xương hàm cho hô hai hàm, cười hở lợi và lệch mặt Orthognathic surgery for bimaxillary protrusion, gummy smile, and facial asymmetry

This was one of the more challenging orthognathic cases managed by our team, combining three distinct dentofacial problems: bimaxillary protrusion, excessive gingival display, and facial asymmetry.

The patient was studying abroad and had only a limited period of time available in Vietnam. She had previously undergone several years of orthodontic preparation for orthognathic surgery.

Clinical and radiographic assessment demonstrated bimaxillary protrusion, vertical maxillary excess, resulting in excessive gingival display on smiling, together with skeletal asymmetry.

The surgical objective was therefore not simply to move both jaws posteriorly. The treatment had to simultaneously address the three-dimensional position of the maxilla, anterior dental protrusion, occlusion, skeletal asymmetry, and the resulting soft-tissue appearance.

Surgical planning

In the maxilla, a Le Fort I osteotomy was performed with superior repositioning to correct the vertical maxillary excess and reduce excessive gingival display.

However, the patient also presented with significant protrusion of the anterior dentoalveolar segment. An anterior segmental osteotomy (ASO) was therefore incorporated to allow posterior repositioning of the maxillary anterior segment.

This strategy allowed two components of the deformity to be controlled relatively independently: the vertical position of the maxilla as a whole and the anteroposterior position of the anterior dentoalveolar segment, avoiding the need for excessive posterior repositioning of the entire maxilla.

In the mandible, a bilateral sagittal split osteotomy (BSSO) was performed to correct mandibular position and asymmetry. A mandibular ASO was simultaneously performed to retract the lower anterior dentoalveolar segment and further correct the bimaxillary protrusion.

When skeletal symmetry does not produce facial symmetry

One of the most challenging components of this case was the genioplasty.

When the chin segment was positioned according to skeletal symmetry alone, the overlying soft-tissue chin remained visibly deviated to the left.

This illustrates an important consideration in orthognathic surgery: skeletal symmetry does not necessarily translate directly into soft-tissue symmetry.

Ultimately, what determines the visible facial result is the soft-tissue envelope rather than the skeletal anatomy seen on CT.

For this reason, the chin segment was intentionally translated further toward the right than would have been required to achieve ideal skeletal symmetry. In other words, a degree of planned overcorrection was accepted at the skeletal level in order to achieve a more balanced external facial appearance.

This case demonstrates why orthognathic surgical planning cannot rely exclusively on skeletal landmarks, reference lines, or numerical measurements. The ultimate objective is harmony between facial appearance, soft-tissue balance, function, and occlusion.

Outcome

Following surgery, substantial improvement was achieved in the patient's bimaxillary protrusion, excessive gingival display, and facial asymmetry. A reasonably good intercuspation was established, and masticatory function returned to near normal.

As with any orthognathic procedure, minor discrepancies may exist between virtual surgical planning and the final postoperative result. The overall outcome should therefore be evaluated not simply by absolute correspondence between the planned and postoperative skeletal positions, but by considering facial balance, the soft-tissue response, occlusion, and function as a whole.

Most importantly, the improvement in facial balance resulted in a significant increase in the patient's confidence.

Postoperative orthodontic treatment was subsequently continued to refine the occlusion and consolidate the final result.