Chin wing osteotomy trong điều trị bất đối xứng xương hàm dưới Chin wing osteotomy for complex mandibular asymmetry

In orthognathic surgery, achieving the correct relationship between the dental arches does not necessarily produce a symmetrical lower facial contour.

This becomes particularly relevant when the inferior border of the mandible is geometrically discordant with the orientation of the dental arch. Even after the maxilla and mandible have been repositioned into an appropriate skeletal and occlusal relationship, substantial asymmetry of the mandibular border and chin may remain.

Chin Wing osteotomy provides a means of addressing this component of the deformity independently.

When occlusion and mandibular contour represent different problems

Conventional orthognathic procedures such as Le Fort I osteotomy and bilateral sagittal split osteotomy (BSSO) primarily reposition the maxilla and mandible to correct skeletal relationships, occlusion, and facial balance.

Conventional genioplasty can independently modify the position and morphology of the chin.

Between the chin and the mandibular angle, however, lies another important aesthetic structure: the entire inferior border of the mandibular body.

In patients with complex facial asymmetry, the deformity may involve not only mandibular position but also the shape, height, and curvature of the lower mandibular border on each side.

The Chin Wing technique creates an extended inferior mandibular segment running from the chin toward the angle. Once mobilized, this segment can be repositioned relatively independently of the tooth-bearing portion of the mandible.

This allows the surgeon to control the chin–jawline–angle contour as a separate aesthetic unit, while the dental arches and skeletal occlusion are managed through conventional orthognathic movements.

Complex mandibular asymmetry with skeletal Class III malocclusion

In this patient, the two sides of the mandible differed in shape, position, and dimensions.

In addition to the asymmetry, significant mandibular overdevelopment resulted in a severe skeletal Class III relationship.

The maxillary arch also demonstrated transverse and morphological discrepancies that required correction.

If treatment had been limited to Le Fort I osteotomy and BSSO, the dental arches could have been repositioned into an appropriate relationship, but substantial asymmetry of the inferior mandibular border would have remained.

In other words, the occlusion could be corrected without fully correcting the lower facial contour.

This was the rationale for incorporating a Chin Wing osteotomy into the surgical plan.

Three components of the deformity, three complementary surgical strategies

The treatment plan incorporated three principal components.

A Chin Wing osteotomy was performed to independently modify the inferior mandibular border, improve symmetry between the two sides, and reconstruct the contour of the lower face.

A bilateral sagittal split osteotomy was performed to set the mandible back and correct the underlying mandibular excess and skeletal Class III relationship.

In the maxilla, a two-piece Le Fort I osteotomy was performed. This allowed maxillary advancement together with correction of the transverse and arch-form discrepancy, while controlling the occlusal plane and minimizing postoperative transverse malocclusion.

Each procedure therefore addressed a different component of the deformity:

Segmental Le Fort I osteotomy addressed the maxilla and dental arch.

BSSO addressed mandibular position and the maxillomandibular relationship.

Chin Wing osteotomy addressed the inferior mandibular border and lower facial contour.

Three-dimensional planning for Chin Wing osteotomy

Chin Wing osteotomy requires precise control of the osteotomy design.

The osteotomy extends along the mandibular body in close anatomical relationship to the inferior alveolar neurovascular canal, dental roots, and inferior mandibular border. Furthermore, the final position and morphology of the mobilized segment directly determine the postoperative jawline.

For this patient, both the osteotomy design and the intended position of the Chin Wing segment were therefore planned preoperatively in a three-dimensional virtual environment.

A patient-specific cutting guide was used to transfer the planned osteotomy to the surgical field, while a patient-specific positioning guide assisted in reproducing the intended final position of the mobilized segment.

This approach is particularly useful in facial asymmetry, where the two sides of the mandible cannot simply be treated with identical symmetrical movements.

From surgical training to clinical application

I had the opportunity to learn the Chin Wing technique from Professor Gwen Swennen during my surgical training in Belgium.

During this period, Dr. Gianluca Renato de Fazio and I also had the opportunity to participate in designing surgical guides for Chin Wing procedures performed by Professor Swennen.

I subsequently incorporated this experience into my clinical practice in Vietnam. By the time of this case, I had applied the technique in approximately ten patients presenting with different patterns of lower facial deformity.

Correct occlusion does not necessarily create a symmetrical jawline

At six months after surgery, the patient demonstrated substantial improvement in both the maxillomandibular relationship and lower facial symmetry.

The particular value of Chin Wing osteotomy in appropriately selected patients lies in its ability to address a problem that conventional orthognathic movements may not completely resolve:

the position of the dental arch and the contour of the inferior mandibular border do not necessarily need to move together.

By treating these as separate components of the deformity, it becomes possible to pursue both an appropriate occlusion and a more harmonious mandibular contour.

In complex facial asymmetry, the ultimate objective therefore extends beyond positioning the jaws correctly. It involves controlling the three-dimensional morphology of the entire lower face.