One of the commonly used methods in facial cosmetic surgeries, is using different prostheses, for augmentation of a part of the face. Different types of prostheses have been designed for different parts of the face, and they are available in the market. In most cases, the prostheses are used for augmentation and enlargement of a part of the face. But in certain cases, they can be used for facial reconstructive or asymmetry surgeries.
In the figure below, different areas of the face are shown. Prosthesis can be used for augmentation of these parts.
Compatibility of prosthesis with body, is one of the most important criteria, and this compatibility must be in a way that prevent adverse reaction in the body. On the other hand, the consistency of the prosthesis must be similar to the tissue that is supposed to be augmented. For example, prosthesis of lips must be very soft, while a prosthesis on the bone must be firm.
Shape and size of prosthesis are the features that are determined at the time of consultation before surgery.
One of the best conditions of using prosthesis is when low bone growth causes a defect in face, for example when bones of chin or cheeks are small and not grown.
Most cases of using prostheses for augmentation are related to chin. Many people, because of their small chin, choose chin augmentation for having a beautiful face. After chin, cheek augmentation by prosthesis is the most common use of prostheses for face.
Many people know about augmentation of these two parts of the face by prosthesis. But there are other parts such as the angle of the mandible which its augmentation can improve beauty of face. Consultation for this kind of surgery is very helpful.
Most of the time facial prostheses are placed on the bone. In such cases we can attach the prosthesis to the bone by special screws, in order to minimize the risk of prosthesis movement.
Sometimes prosthesis can be used in soft tissues such as lips. In these cases, because the prosthesis is touchable and because of the impact that it can have on lips movement, some patients are not satisfied with the results. In contrast some people are satisfied because their lips are attractively augmented.
Asymmetry after implantation of the prosthesis is one of the most common side effects after surgery. In most cases this asymmetry is small and does not need a reform. Here are the most important causes of asymmetry. If the prosthesis is not fixed during surgery or a hit happens after the surgey, asymmetry may happen. Another side effect of prosthesis is numbness in the area around the prosthesis.
Fortunately this numbness will disapear after some time. Due to the fact that the prosthesis is considered a foreign object for the body and body cannot protect it against microbes, there is the possibility of infection for all prostheses. However, some of prostheses, due to the adaptability and being porous (medpor prosthesis), somehow become something like a part of body and tissues can grow in them. On the whole the probability of infection for face prosthesis is less than 1%.
During the process of aging some people may experience Facial volume loss caused by facial muscle and fat atrophy. In these cases we use prostheses for facial volume. Because the result is better than fat injection. But most of patients tend to use other methods for rejuvenation.
Of course one way for facial augmentation (eg cheeks) is using body’s natural tissues. To do so we can use a bone,cartilage or a soft tissue. One of the advantages of this method is that the risk of infection is less than surgery with prostheses. To use this method, first you must pick up a bone or cartilage from another part and this increases the time of surgery and the recovery period after surgery would be longer.
Fortunately with the use of the prosthesis, time of surgery is reduced and because modern prostheses are compatible with body, the risk of infection is very low. Therefore prosthesis implantation as a standard way of facial augmentation is accepted across the world.
The reaction of various prostheses in body are different. In the case of silicone prostheses, which are commonly used, the reaction of body is that a membrane appears around the prosthesis and with formation of the membrane, somehow prosthesis would be fixed and without movement.
The compatibility of medpor prosthesis is more. In a way that body tissues can grow in the small holes of prosthesis. So the risk of infection will be significantly reduced. sometimes this prosthesis is like a normal bone and beautify the place in which it is located.
silicone prosthesis is one of the earliest types of prostheses. Its compatibility with body has been proved (it has been used since 100 years ago). Here are Some of its advantages: it is soft, cheap, and easy to remove.
One of the disadvantages of this prosthesis is that when it is implanted on a bone, the bone absorb it after some time. In most cases this does not affect the final result very much. On the other hand, the membrane around the prosthesis is not very resistant and cannot prevent displacement of the prosthesis. so in such cases most surgeons prefer a better method for keeping it fixed.
Unlike silicone, Medpor prosthesis or Porous polyethylene has more consistency. This makes it to be more similar to a bone and it does not cause absorption. Being Porous causes more compatibility with body. In a way that growth of body tissues inside the holes causes the prosthesis to be attached to the place and consequently risk of displacement is reduced. On the other this feature makes it difficult to remove the prosthesis.
Gore-tex or polytetrafluoroethylene is Porous like Medpor prosthesis and tissues can grow in it. This prosthesis is softer than Medpor prosthesis. For attaching it to the place, we use screws or Stitch most of the time.
Most of facial prostheses can be implanted through mouth. Although some surgeons believe that in this way risk of infection after surgery is more, statistical findings show that oral prosthesis implantation does not affect risk of infection that much. The biggest advantage of this method is that no trace of surgical incision can be seen.
Another way for prosthesis implantation is through skin or Extraoral method. In this way the surgeon incise skin for implantation. Fortunately, this incision is in areas that could not be seen normally (for example under the Chin) or in areas like edge of the eyelid, where would be without any trace. One of the advantages of extraoral method is that you can have other cosmetic surgeries simultaneously. For example, for a person with a double chin, we can incise under the chin, implant the prosthesis, and also remove the excess fat.
Anyway, choosing intraoral or extraoral method depends on the patient and surgen’s decision. Most of the time this case is considered in consultation before the surgery.
Fixing prostheses by screws has various advantages. One of them is that the risk of displacement of prosthesis is reduced and when the prosthesis is attached to the bone, the distance between them disappears. In cases where there is a distance between the prosthesis and facial skeleton, the distance can cause augmentation more than desired extent. An example help you understand it. Assume that the desired chin augmentation is 6 mm. If the distance between the prosthesis and the bone is 2 mm, the augmentation would be 8 mm. And this is the result that you may not satisfied with.
One of the problems with fixed prosthesis by screws is that if you are not satisfied with the result, removing the prosthesis takes more time. On the whole the way of fixing prostheses should be chosen by the surgeon, and sometimes on the basis of an agreement with the patient.
As we can see in the picture below, if we draw a line from the tip of the nose to the Chin, distance of the line from the upper lip is 4mm and from the lower lip is 2 mm. in cases where the Chin is back, by drawing a line with the mentioned distance form the lips, we can obtain the area to which the Chin can augmented. Nowadays, with the use of existing softwares, we can simulate the placement of prostheses and determine suitable size of prosthesis accurately.
The natural Labiomental angle is 21±113° for men and 14±121° for women. For people who have a small and back Chin, in most cases this angle is wider and by prosthesis implantation, we can reduce its value. In cases where this angle is closed before the surgery, Chin implantation may cause it to become worse and this affects the result. So considering the angle and designing the image of patient by softwares can prevent undesired results.
Mentalis muscle may be damaged during intraoral placement of the chin prosthesis. This muscle is responsible for bringing up the lower lips and its damage can cause lower teeth to be seen and the biomental angle would be wider. This does not happen in cases that we implant prosthesis through the incision under the Chin. In intraoral cases where the muscle is cut off, the surgeon can prevent complications by correct restoration.
In such cases it is better to remove the prosthesis and replace it with a prosthesis with appropriate size. For asymmetric problems we can move the prosthesis and fix it in an appropriate place.
In cases that a little augmentation of cheek, chin or every part of the face is enough, we can inject fat. But when more augmentation is needed (usually more than 4 to 5 mm) it is better to use prostheses. In cases where the prosthesis is used, the area is completely augmented and this case is more appropriate for people who want a face with specific angles. After fat injection, the face seems filled and round and the angles are less clear. This is the case for people who want to have a round face.
For people who want to have a thin face with augmented Skeleton, using prostheses is preferred.
Depending on the type of complication, different treatments are done. In cases where there is only a little numbness around it, usually it is not necessary to take an action and this case can be resolved on its own. And also for a slight displacement of the prosthesis, usually we do not need a specific therapeutic action but for severe displacements, the prosthesis must be implanted in the appropriate place again. In prostheses infections, in most cases it is necessary to remove the prosthesis. In such cases, after the complete elimination of infection, we can implant the prosthesis again.