What can I do to even out the appearance of my bottom lip? (photos)

The swelling may possibly relate to the presence of scar tissue or possibly even lymphedema in the side of the lower lip that was traumatized for twelve years. If this is the case, a trial of injectable antiinflammatory agents, such as triamcinolone, would be reasonable in an attempt to shrink the scar tissue and create greater balance in this way with the other side. Alternatively, or if the latter does not work, a hyaluronic acid-based filler can be used to augment the opposite side to achieve greater balance. Make sure that you consult with a board certified aesthetic physician. Best of luck. 

Most doctors will start with one-syringe to avoid overfilling. These fillers, (Volbella, Restylane, Juvederm) are good to create a symmetrical and full lip. PDO NovaThreads can also be used to improve shape and also provide lift. Fat or implants are a permanent alternative. I recommend getting a formal evaluation with a facial sculpting expert. Best, Dr. Emer

Dear techtalkto,
I typically use Juvederm for my lip sculpting. There are two main focuses of lip injections, adding volume and actually sculpting the shape. Both involve injecting the filler in different areas of the lips and patterns.
I would recommend finding a plastic surgeon to perform you lip injections. Most of my patients have results that last at least 6 months.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery