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What does it change?: Cutting or moving bone, and removing fat from inside the cheek. The least reversible group on this site.
Is there anything short of surgery?: Partly. If a square look comes from the chewing muscle, botulinum toxin is used; for fat under the chin, deoxycholic acid. Bone is not changed by a procedure.
Can it be undone?: It cannot be undone. Bone that was cut and buccal fat that was removed do not come back.

There are no numbers and no citations in this box. What has been established, and how far, is below.

First: is the squareness bone, muscle or fat? The three have completely different answers.

Muscle means botulinum toxin. Not surgery, and it returns in a few months
Fat under the chin has deoxycholic acid — one of the rare entries on this site carrying two placebo-controlled phase 3 trials
Bone means facial contouring or orthognathic surgery. From here no procedure substitutes

Orthognathic surgery sits differently on this axis. It also treats the bite, so it is not a purely cosmetic decision.

Buccal fat removal carries a warning that only shows up later. The fat pad inside the cheek shrinks on its own with age. Someone who had it removed at 25 may look more hollow at 45, and there is no way back.

Genioplasty has a non-surgical option — chin filler. The difference is that filler can be dissolved.

This site does not cover prices, clinics or testimonials.

Options before surgery

Used for the same concern but not surgical. These do carry evidence grades.

Moderate evidenceBotulinum toxinInjection
Moderate evidenceHyaluronic acid fillerInjection
Moderate evidenceDeoxycholic acid injection (submental fat)Injection

Operations for this concern

Surgery on this site is not yet graded for evidence. Reversibility is shown in place of a grade.

Facial bone contouringCannot be undone
Buccal fat removalCannot be undone
Orthognathic surgeryCannot be undone
GenioplastyOnly partly