Điều trị sai khớp cắn loại ii kết hợp hô xương ổ răng hai hàm Management of class ii malocclusion with bimaxillary dentoalveolar protrusion

Protrusion of the lower face is not always caused simply by the position of the jaws. In some patients, the deformity results from a combination of skeletal jaw discrepancy and protrusion of the anterior dentoalveolar segments.

This case illustrates such a combination: a skeletal Class II pattern with mandibular and chin retrusion, together with bimaxillary dentoalveolar protrusion. Successful treatment therefore required independent correction of both components to improve the facial profile and occlusion.

From prolonged orthodontic treatment to orthognathic surgery

The patient had undergone orthodontic treatment for several years without achieving the desired correction of the underlying facial and skeletal discrepancy. He was subsequently referred by an orthodontic colleague for assessment for orthognathic surgery.

Clinical and radiographic evaluation demonstrated several key features:

Prominence of the lips and anterior dentoalveolar region with an acute nasolabial angle.

Mandibular retrusion relative to the midface.

A retruded chin contributing to a convex facial profile.

Significant proclination of the lower incisors associated with anterior dentoalveolar protrusion.

A desire for additional refinement of the mandibular angle and lower facial contour.

Simply advancing the mandible or retracting the anterior teeth alone would therefore have been insufficient to address the complete deformity.

Surgical strategy

In the maxilla, the first premolars were extracted to create the space required for segmental repositioning. A Le Fort I osteotomy was then performed and the maxilla divided into three segments through the extraction sites.

This allowed independent control of the anterior maxillary segment, with correction of upper incisor inclination and posterior repositioning of the anterior dentoalveolar complex. The objective was to reduce maxillary protrusion and improve the relationship between the nose, lips, and lower facial profile.

In the mandible, the first premolars were also extracted. A bilateral sagittal split osteotomy was combined with an anterior subapical osteotomy.

This enabled two different movements to be performed simultaneously: the mandibular basal segment could be advanced to correct mandibular retrusion, while the anterior dentoalveolar segment could be independently repositioned to upright the lower incisors and reduce anterior protrusion.

In other words, the operation allowed us to advance the mandible while independently controlling the position of the lower incisors, rather than forcing the skeletal base and dentoalveolar segment to move together.

Bilateral mandibular angle contouring was additionally performed to refine the lower facial contour according to the patient’s aesthetic objectives.

Treating the face, not simply the teeth

An important aspect of this case is the distinction between the position of the skeletal jaw base and the position of the dentoalveolar structures supported by that base.

A patient may simultaneously have a retruded mandible and markedly proclined, protrusive lower incisors. When the teeth are considered in isolation, mandibular advancement may appear contradictory to the objective of reducing protrusion. Once the skeletal and dentoalveolar components are analyzed separately, however, both problems can be corrected simultaneously.

This was the rationale for combining segmental dentoalveolar osteotomies with bimaxillary orthognathic surgery in this patient.

Digital planning and surgical transfer

All skeletal movements were planned preoperatively in a three-dimensional virtual environment.

Virtual planning allowed the positions of the jaws, dentoalveolar segments, incisor inclinations, chin, occlusion, and overall facial profile to be assessed together before the final surgical movements were determined.

Once the plan had been finalized, patient-specific surgical guides and positioning devices were designed to assist in transferring the planned skeletal positions from the virtual environment to the operating room.

Digital planning and individualized surgical guidance have been incorporated routinely into my orthognathic surgery workflow since 2021.

The role of postoperative orthodontics

At approximately five months after surgery, the patient demonstrated substantial improvement in facial balance and occlusal relationship. The perioral protrusion was reduced, while advancement of the mandible and chin created a more balanced facial profile. Mastication, mouth opening, and speech were functioning well.

Surgery, however, does not represent the end of treatment.

Postoperative orthodontics plays an essential role in refining individual tooth positions, improving intercuspation, and consolidating the final occlusion. A successful orthognathic outcome therefore depends on close coordination between the surgeon and orthodontist throughout the treatment process.

This case illustrates an important principle: effective correction of facial protrusion begins by determining how much of the deformity originates from the skeletal jaw bases and how much originates from the dentoalveolar segments and tooth position.