#6-1. Application in plastic surgery: Micrognathia

Dr. Jung-whan Baek (H Plastic Surgery)

In this article, I will present a case where a new treatment approach was applied to congenital facial bone deformity.

Application of 3D printing in medicine has the following three advantages.

1. Improved surgical accuracy

2. Shorter operation time

3. Development of new surgical techniques

With 3D printing technology, surgical accuracy improved drastically from old techniques that relied on the surgeon’s experience and hunch. Shorter operation time also means faster recovery for patients. I will describe how 3D printing used in correction of micrognathia led to development of new surgical techniques.

Micrognathia, also known as mandibular hypoplasia, is characterized by abnormally short vertical length of the lower face and chin and withdrawn mandible. The available remedies in the past included SSRO (sagitttal splitting ramus osteotomy) used to correct the retracted chin or advance genioplasty or chin implant for elongating the chin. However, each of these procedures could only elongate the chin and failed to correct the shape of the chin or advance the chin.

Image 1. Frontal photograph and lateral X-ray image of the patient with micrognathia.

<Image 1> shows a patients with short (red line) and retracted (the mentum-cervicomental angle distance; yellow line) chin. SSRO advances the chin forward, lengthening the distance between the mentum to cervicomental angle but SSRO can round the gonial angle further and cause an unnatural shape of the chin in patients with a short chin. Autologous bone advance genioplasty can enhance the distance from the mentum to cervicomental angle but the advanced part and the remaining part of the mandible form terraces, eventually leading to osteotomy of the mandibular bone to eliminate the secondary angle. The chin implant is the most commonly carried out and can elongate the chin but the thickness of the implant has to increase with its width. This method also fails to lengthen the vertical length of the chin. Previous surgical options could not bring the desired shape of the chin in micrognathia. The most ideal correction would increase both the vertical length of the chin and the mentum-cervicomental angle distance.