Can implants replicate the aesthetic effects of Maxillomandibular Advancement (MMA) surgery?

I perform both of these cosmetic procedures in my practice and the answer to your question depends on my factors. For example, if your teeth are in an acceptable bite or occlusion, then your facial bony deficiency is probably minimal and facial implants can make a significant difference and mimic the results of maxillomandibular surgery. If your bite discrepancy is significant and the teeth don't match up well, facial implant surgery will only provide marginal improvement. In general, I like the results that malar and submalar implants can provide. I hope this is helpful  

Properly designed and selected facial implants can replicate all the external facial effects of bimaxillary surgery with the exception of pushing out the upper lip. This can only cuff because of the push of the teeth.

 Upper and lower jaw surgery is very different than just placement of  cheek and chin implants. They each produce different results. Cheek and chin implants can be performed under local anesthesia as an outpatient procedure.  Cheek and chin implants are manufactured in a large array of both sizes and shapes, and each size and shape given different result. Upper and lower jaw surgery is performed by an oral surgeon to make sure that the teeth fit together properly and is performed under general anesthesia in a hospital setting with an overnight hospital stay for at least one or two nights. For many examples and more information about cheek implants and chin implants, please see the link and the video below

 Hi, in my experience and humble opinion any type of bone surgery (Maxillary or Mandibular Advancement) is very invasive with the inherent added risks of unwanted side effects including injury to motor and sensory nerves as well as prolonged recovery.  For these reasons it's best to have several consultations with experts in "facial shaping" to compare risk and rewards of the available treatment options.   I have performed many facial shaping procedures using dermal fillers, silastic facial implants (cheek implants, chin implants, lip implants), liposuction and/or facelifts for over 30 years.  Since every face is different, non smiling photos of your face from the front and side would help in the evaluation.  According to my "beauty principles" it's not just about "forward facing" which I assume is another phrase for "projection" but is all about the "aesthetic" shape of key facial features.
 Following my beauty principles, women look the most feminine, youthful and attractive with heart shaped faces.  Heart shaped faces have cheeks that are full and round in the front.  Conversely, men appear chiseled and handsome with angularity in the cheeks, chin and mandibular angles.  Cheek augmentation with a dermal filler or using cheek implants for a permanent enhancement will create full, round cheeks that will feminize or masculinize the entire face.  I have a particular issue with submalar cheek implants which as the name implies are placed "below" the cheek thereby rendering them incapable of changing the shape of the cheek bone(s) themselves.  In my mind, the role of a cheek implant is to create the appropriate male or female aesthetically shaped cheek.  Logically, to me this means placing the properly shaped silastic implant "over" the cheek bone itself.
 I have performed many Chin Augmentations using chin implants for over 30 years.  If the chin is weak, this creates an imbalance making the nose appear larger, the mid face top heavy and the lower face look short that de-emphasizes the lips and allows early formation of a double chin.  Chin augmentation using a chin implant will add projection to the chin creating harmony and balance to the lower face. 
 I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty.  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  Tear troughs are often found when the cheeks themselves are lacking the necessary forward projection in the anterior or front section of the cheeks.  In these cases, augmenting the cheeks with proper placement of a suitably shaped silastic cheek implant offers a far more aesthetic correction than a tear trough implant that is only reshapes the very upper inside area of the cheek.
Hope this helps.