Genioplasty

Mandible refers to the bone covering the lower teeth which extends to the temporomandibular joint in front of the ears. Besides, chin refers to the small part located at the lower front of mandible (figure 1). In order to understand genioplasty, it is important to first understand the relationship of chin as part of mandible. There are various types of genioplasty, Dr. Hsieh will try to avoid using simplified approaches such as chin implant and chin augmentation to describe genioplasty.

Presently, genioplasty is categorized into osteotomy genioplasty (figure 2) and synthetic bone graft (figure 3). There are different perspectives of considerations to take into account for choices between osteotomy genioplasty and synthetic bone graft. Dr. Hsieh will try to use words that are easy to understand in describing treatments for different chin conditions, so that readers can differentiate the strengths and weaknesses between these two types of surgeries.

Basic Differences of Surgery:
Osteotomy genioplasty is usually performed under general anesthesia. The surgeon will detach the chin and mandible with micro-bone-saw and reattach the chin bone to a desired position before securing with screws and plates.
In most cases, genioplasty with synthetic bone graft can be performed with local anesthesia and this type of procedure is frequently adopted to correct mildly to moderately receding chin.

Correction for Receding Chin or Microgenia:
Person with receding chin frequently has respiratory depression leading to different severity of sleep apnea disorder. By adopting sliding genioplasty to move the chin bone forward (which concurrently moves forward muscles behind the chin), airway can be opened up to improve sleep apnea condition. On the contrary, procedure with synthetic bone graft may have the same aesthetical effect but no effect on enhancing respiratory problems. If the chin retrusion exceeds 7mm, osteotomy genioplasty or combining with orthognathic surgery can be considered because it will provide more natural result than implanting a synthetic bone graft larger than 7mm.

If chin augmentation is required with correcting receding chin, application of synthetic bone graft will provide a better result. In some cases, combining osteotomy genioplasty and surgery with synthetic bone graft can achieved better aesthetic result besides improving respiratory function.


Correction for Retrogenia:
The best option to correct retrogenia is osteotomy genioplasty. When a prosthetic implant is placed on top of slanted chin (even though correction by crafted implant or chin bone reshaping is applied), a satisfactory result in correcting slanted chin usually cannot be obtained. Besides, this may even lead to manifestation of the slanted chin.

Correction for Long Chin (Vertical Chin Excess):
It is rather obvious that long chin requires correction through osteotomy or combining with orthognathic surgery to shorten the chin.

Considerations for other aspects:

Considerations for materials of chin implant:
Generally, doctors will select materials of chin implant according to the following characteristics:

Synthetic bone graft/Medpor:
It is a type of high-density porous polyethelene. There are various strengths for this type of material. It has good biocompatibility and will not be absorbed by chin bone. Besides, it has no issue with spasticity of soft tissue and dislocation of implant. On the contrary, this type of material has higher cost and surgical difficulty as compared to other materials.

Chin silicone implant:
Chin implant made of silicone also has good biocompatibility. Moreover, the advantages of silicone are its cheaper cost, ease of surgical insertion and crafting. However, weakness for this type of material is its unpredictable degree of absorption by the bone. When the material is absorbed by the bone, it may affect the maintenance of aesthetical appearance and stability. Furthermore, spasticity of capsule can easily result in dislocation of silicone implant. Occasionally, revised surgery is required to resolve these issues.

Recovery:
Osteotomy surgery and surgery with synthetic bone graft (Medpor) have similar recovery period. Since the incisions are intraoral, there is no external wound. Generally, 60-70% of post-operative swelling would subside within a week and 80-90% of swelling will be resolved in two weeks. Liquid diet will be administered for 3 days post-operation and soft diet is prescribed from Day 3 to Day 7 post-operation. A week after the surgery, patients are able to gradually consume regular diet.

Conclusion:
Dr. Hsieh tries to follow principles in considering the surgical approaches. As a matter of fact, every individual has different needs and various considerations. Therefore, each case is unique and one of its own. Same approach should not be applied on every individual and patients should not compromise to the surgeon’s skills or accessible medical equipments.

In recent years, Dr. Hsieh has specialized in the study of sleep apnea and discovered that most patients with receding chin tend to have obstructive sleep apnea (OSA). After advancement sliding genioplasty, the respiratory path will conspicuously open and symptoms such as sleep apnea or snoring are improved. Besides, there is great enhancement in daytime vitality. Therefore, some patients who formerly do not concern about appearance (especially middle-aged male) would undergo osteotomy genioplasty in order to improve sleep quality and remove their ventilator.