Benefits of External or Internal Incision Site for Chin Implant?

My personal preference is the external incision.  The infection rate is lower (the mouth is impossible to completely sterilize), and implant positioning tends to be more favorable than with the intraoral approach.

An external incision under the chin is preferable to the intra-oral route for several reasons.  With an external incision, there is lower risk of infection and the implant is less likely to migrate.  The implant is placed directly over the chin bone and once healed, does not require a screw to keep it in place. 

When placed through an incision under the chin, your surgeon is able to place the implant as inferior as the patient desires.   

This is a point of ongoing debate amongst plastic surgeons. I personally prefer to do my chin implants by using an external incision made just underneath the chin. I prefer doing chin implants in this manner because there is less chance of an infection occurring using this method. When you place a chin implant thru the mouth (internal incision), you cannot do so in a completely sterile manner. By definition, the mouth will always be contaminated with bacteria. If you are attempting to place a sterile implant via a non-sterile route, you will risk developing an infection and possible need to remove the implant. I don't think there is an credence in being able to place the implant any lower along the jawline using an internal approach. If anything, you would have an advantage coming from an external approach. Find a board certified plastic surgeon in your area who has plenty of photo examples of chin implant/augmentation and is willing to explain in detail their preferred method.