Procedure to fix uneven lip? (photos)

Thank you for sharing your question and photograph.  It appears that you had a fair amount of scar tissue develop along your right upper lip (left in the picture) during the healing phase of your laceration.  This has caused you the fullness and irregularity relative to your left upper lip.  Correction will require a reapproximation of the tissues while removing a significant portion of the scar to better match your uninjured side.    Be sure to see a board certified plastic surgeon in consultation.

it looks like that was a pretty deep cut when you were 5 years old! In addition to the scarring, the cut likely severed some of the muscle, causing the bulge. It would be interesting to see what this looks like when you smile and pucker. Reapproximating the muscle after all these years is not easy and may not be able to be done. I think what can be done easily is to remove the scar tissue and a bit of the wet mucosa that pooches out. This should even out your lip at rest, but it may not be completely symmetrical when you move your mouth. See a board certified plastic surgeon (particularly a pediatric plastic surgeon who does a lot of cleft lip work) for an in person consultation.