[Paper Review] Technological Advances and Real-World Applications in Modern Facial Contouring Surgery: Correction of Facial Asymmetry

Hello, this is Director Jo Hyun-woo of Ibteuk Plastic Surgery.

Today, after a long time, a paper was delivered to me from Google, so I would like to review it.

The paper I will review today is

It is a paper published in a place called IntechOpen, and it was written by a dentist.

It discusses the technological advances and practical applications of modern facial contouring surgery. Since 3D technology has been continuously advancing these days, it is an area I am also very interested in, so I read it.

When looking at the paper, it explains that in the past, when performing plastic surgery to correct facial asymmetry, surgeons analyzed asymmetry using 2D photos or X-rays and made surgical plans, but nowadays 3D computed tomography (CT) and virtual surgical planning (VSP) technology are widely used.

Thanks to this, it explains that more precise and detailed correction has become possible.

1. The Need for Facial Contouring Surgery and the Introduction of Advanced Technology

The main goal of facial contouring surgery is to improve facial symmetry and harmony, creating a more natural and aesthetic appearance.

Asymmetry can occur not only due to congenital factors but also due to various causes such as trauma or lifestyle habits, and correction requires precise adjustment of multiple elements, including bone, muscle, and skin tissue.

In the past, asymmetry was checked visually and corrected in a rough manner, but recently, 3D imaging technology has made detailed analysis possible, and through this, optimal correction methods can be derived using CAD/CAM (Computer-Aided Design and Manufacturing) technology.

1.1 The Role of 3D Virtual Surgical Planning (VSP) and CAD/CAM Technology

3D virtual surgical planning allows accurate modeling of a patient’s facial asymmetry and enables testing of various surgical methods.

CAD/CAM technology makes it possible to pre-design and manufacture patient-specific surgical guides and fixation devices, increasing surgical precision.

For example, if a surgical guide tailored to the patient’s bone structure is made through CAD technology, it can reduce errors during surgery and help prevent recurrence of facial asymmetry.

In this table, it says that when facial asymmetry is present, the degree of tooth misalignment is checked, and based on 2 mm, it is decided whether to perform double-jaw surgery. It also says that depending on the frontal jaw angle, the decision is made whether to perform mandibular surgery or contouring surgery.

2. Custom Plates and Fixation Devices

It says that custom plates and fixation devices used during surgery are important factors that determine the success and stability of the operation.

These days, they are customized and designed to match the patient’s bone structure, helping to fix the bones in the originally planned position after surgery.

It seems to be a commonly used method in double-jaw surgery.

In addition, by using CAD/CAM technology, the cutting lines and fixation positions set in the surgical plan can be implemented accurately.

To minimize errors that may occur during surgery, fixation positions are precisely designed in advance.

fig.2A: This is the design of a surgical guide marked on a preoperative virtual skull model, with the osteotomy line, the amount of bone to be removed, and the fixation position preset.

fig.2B: This is the design of a fixation plate custom-made to fit the skull model, and the individually tailored plate is designed and fixed according to the actual position of the bone.

3. Correction of Asymmetry Through Adjustment of Frontal Ramal Inclination

FRI (Frontal Ramal Inclination) is a factor that greatly affects left-right facial balance and plays a very important role in correcting asymmetry.

When FRI adjustment is needed, simply cutting the bone to correct it may have limitations.

Therefore, it is necessary to adjust the angle and direction of the FRI to match symmetry more precisely.

3.1 Difficulties in FRI Adjustment and the Need for Advanced Technology

In the past, FRI was adjusted based on 2D image analysis, but the low precision made it difficult to achieve the desired results.

However, through 3D virtual models and CAD/CAM technology, the patient’s FRI can be accurately analyzed and adjusted.

If intraoperative adjustment is needed, VSP can be used to simulate it in advance, predict the postoperative outcome, and adjust it in real time during surgery.

In particular, when adjusting the FRI, minimizing joint movement can improve the stability of the result and reduce errors.

fig.3A: A preoperative skull model with different left and right FRI values. This indicates asymmetry that needs correction.

fig.3B: An example in which the left side is rotated inward to increase the FRI, and the right side is rotated outward to decrease the FRI.

4. Zygoma Correction and Facial Contouring Surgery

Facial contouring surgery is mainly effective in cases of pronounced zygomatic prominence.

When the asymmetry is not severe, contouring surgery improves facial symmetry and creates overall harmony.

Because the zygoma has a major influence on facial impression, correcting protruding areas can greatly improve overall balance.

fig.4: An example showing asymmetry that remains even after zygoma correction in a severe facial asymmetry case. Additional contouring surgery may be needed.

4.1 Strategies and Procedures for Zygoma Reduction Surgery

Zygoma reduction surgery, a type of zygoma correction, adjusts excessive protrusion and makes the facial appearance more harmonious.

In this process, the structure of the zygoma and its impact on the surrounding muscles must be fully considered, and it is noted that if the zygoma moves too far inward, it may restrict mouth opening.

During treatment planning, the position and degree of protrusion of the zygoma should be analyzed precisely so that side effects that may occur during surgery can be minimized.

That is a rather obvious point, but it seems important.

fig.5: An example showing a treatment strategy for restoring zygoma symmetry according to the amount of asymmetry between the right and left zygomas. Depending on the case, one side is reduced or the opposite side is augmented.

It explains how to correct left-right asymmetry using a VSP model.

5. The Need for and Application of Cortical Osteotomy Mandibuloplasty

Cortical osteotomy and mandibuloplasty are effective in balancing left-right symmetry by adjusting mandibular asymmetry.

When mandibular asymmetry is severe, cortical osteotomy can be used to adjust the width of the mandible and secure symmetry of the lower face.

Cortical osteotomy is mainly used to balance the left and right sides of the mandibular angle area, and through VSP, the nerve position can be identified on the virtual model to avoid nerve injury during surgery.

fig.7A: The selected cortical osteotomy area on the right mandible is shown in red on the virtual model.

fig.7B: The left and right sides of the mandible are compared to assess the degree of asymmetry, and a surgical plan is established on the virtual model while considering the nerve position.

6. The Use of Mandibuloplasty and VSP

Mandibuloplasty is mainly used to improve overall facial balance by matching the left-right symmetry of the mandible.

In particular, mandibuloplasty is effective when mandibular asymmetry is not severe, and through simulation of mandibuloplasty with a virtual model, left-right symmetry can be evaluated and planned before surgery.

Through this, it says that side effects during surgery can be reduced and result stability can be secured.

fig.8A: A view of the left side overlaid on the right mandible to analyze asymmetry.

fig.8B: A view showing an appropriate osteotomy line designed to adjust mandibular asymmetry.

In conclusion, the authors say that with technological advances, facial contouring surgery can now be performed more precisely and safely. Thanks to VSP and CAD/CAM technology, patient-specific planning and equipment have been introduced into surgery, minimizing errors and increasing the predictability of results.

However, they also say that limitations still exist in this technology. For example, unexpected postoperative soft tissue changes may cause asymmetry to recur, and satisfaction with the results of some contouring procedures, such as zygoma correction, may vary depending on cultural standards of beauty.

In addition, because soft tissue responses differ depending on the bone structure, patients need a period of adaptation to the surgical outcome for 6 to 12 months after surgery, and it may take time for the results to fully stabilize.

Therefore, in cases of severe asymmetry, it is recommended to evaluate whether additional correction is needed after one year.

The paper concludes that these considerations are important for improving postoperative satisfaction through sufficient communication between patient and surgeon.

It was a paper I read after a long time, so I found it interesting.

In fact, these days, 3D-based surgery is widely performed in double-jaw surgery.

If such a good plan is made, good results can be achieved.

I think it may also be worth considering using such programs to correct asymmetry in the contouring surgeries I perform.

I hope this long paper review was helpful.

Thank you.