Chin filler, fat transfer or implant - which procedure would help elongate my chin and fill in the groove under my lip? (photo)

although this photo is insufficient (a full profile is needed) you likely need chin augmentation. Chin implant would be the best choice. Good luck.

Chin augmentation can be done with implants, a sliding genioplasty, or with the use of fillers.
Fat transfer does not work well for this part of the face.
Your chin already has fairly strong, horizontal projection.
Augmenting the chin in the horizontal plane will deepen The fold above it.
You can only fill in the fold so much.
I suggest having multiple in person consultations with both oral surgeons and plastic surgeons in your community.
Oral surgeons tend to see things more from my facial, skeletal perspective, while plastic surgeons tend to be more oriented towards soft tissue solutions.
I think anyone who is recommending fat transfer should be asked to show you a large number of long-term follow up before and after pictures.
Pictures should be a minimum of 3 to 6 months out from surgery in order to be representative.
If you see impressive, chin, augmentation pictures based on fat transfer that I’m guessing the pictures were taken soon after the procedure was done before has been re-absorbed, and while the area is still swollen. Of the non-surgical approaches, fillers are by far the best option, and can give very good results if you find the right provider.Best,
Matt Hagstrom, MD