Technique for Chin Reduction

Jong-Woo Choi

Woo Shik Jeong

DEFINITION

Facial contours can greatly affect a person’s facial image. In particular, the shape of the chin is one of the most important parts in terms of facial image according to a recent consensus among facial plastic surgeons who perform facial contouring surgery.
There are several ways to perform a chin reduction.
- One is to reduce the whole mandible, including the chin, which is performed through mandibuloplasty.
- The other is to reduce only the chin, which is performed with genioplasty.
In terms of the surgical direction for chin reduction, there are two acceptable methods.
- One is horizontal chin setback, which is associated with the mandible setback or chin setback procedure.
- The other is vertical chin reduction, which is related to vertical reduction genioplasty. This method reduces the volume of the chin using narrowing genioplasty.
This chapter describes how chin reduction can be properly achieved by selecting the best solution from among these various options according to the patient’s status.

ANATOMY

The mental nerve innervates the lower lip and chin region and passes through the mental foramen on the anterior surface of the mandible. The mental foramen is generally located in the apical region of the first and second premolars.¹
However, anatomical variation exists with respect to the mental foramen’s location, and the anterior loop of the mental nerve should be considered with a safety zone left when the osteotomy line is planned.

PATIENT HISTORY AND PHYSICAL FINDINGS

The chin reduction procedure can be applied to patients who complain of a prominent and wide chin or of protrusion of the mentum.
Reduction with mandibuloplasty can improve aesthetic contouring of the chin and the appearance of a square face.

IMAGING

The appearance of the chin is easily visualized on threedimensional computed tomography.²^,³
Panoramic radiographs can also be helpful for locating the mental foramen.

SURGICAL MANAGEMENT

Orthognathic surgery could be a good option for skeletal class III prognathism accompanied by chin protrusion. In contrast to reduction genioplasty, which is performed on the chin alone, mandibular setback resolves issues related to the whole mandible. Sometimes, simple reduction genioplasty cannot produce the desired results for patients with skeletal class III prognathism:
- Regardless of the occlusion, the protruded mandible or chin should be corrected based on the whole facial profile. If the patient has a relative skeletal class III tendency, orthognathic surgery may be a better solution than simple chin reduction or mandibuloplasty would be. If the patient has a normal class I occlusion, clockwise rotational jaw/rotational mandibular setback could be a good alternative.
In the past, mandible angle reduction was the common term for facial contouring surgery in Asia. However, this procedure should now be referred to as mandibuloplasty, as modern aesthetic facial contouring surgery primarily deals with the whole mandible, including the chin, body, and the mandibular angle:
- To reduce the whole mandible, numerous modifications have been introduced, such as mandible angle resection, long curved mandibulectomy, and sagittal mandibular corticectomy.
- Recent standards for mandibuloplasty include longcurved marginal mandibuloplasty with or without narrowing genioplasty. This method for one-piece mandibuloplasty should focus on the shape of the mandible as well as the amount of the marginal resection. Compared with traditional mandible angle resection or mandible reduction, one-piece mandibuloplasty affects the whole mandible.
In contrast to mandibuloplasty, genioplasty techniques mostly affect just the chin. Various genioplasty techniques have been introduced. Advancing genioplasty is the most commonly used technique. For chin reduction, however, vertical reduction genioplasty is preferable.
- Vertical reduction genioplasty can reduce the vertical chin dimension directly with an approximately 1:1 hard-tosoft tissue ratio, whereas the maxillary movement was not correspondent at hard-and-soft tissue ratio. This effect suggests that reduction genioplasty is a very effective and intuitive procedure.
- Whereas vertical reduction genioplasty primarily affects vertical control of the chin, narrowing genioplasty primarily affects horizontal control of the chin. There are various chin shapes, such as the broad chin, square chin, long chin, short chin, and trapezoidal chin, and the shape of the chin greatly influences the facial contour. Narrowing genioplasty has become one of the most popular procedures in facial contouring surgery.
Narrowing genioplasty can be performed with mandibuloplasty of the chin, body, and angle. An alternative method is one-piece mandibuloplasty. There are few differences in these procedures, so surgeons can choose which to perform based on their personal preference.

Preoperative Planning

The extent of chin correction should be determined individually according to the patient’s chin width, the degree of mental protrusion, the course of the inferior alveolar nerve, and the patient’s preference regarding the final chin shape.
For fixation of bone segments, titanium miniplates, lag screws, or wires can be used and should be available.

Positioning