Can Tongue Splitting Be Reversed?
Splitting May Be Reversed Surgically by Removal of Sutures, Excision of Healed Tissue on Edges, and Re-Suturing the Tongue Together. Once Healed, Muscle...
Splitting may be reversed surgically by removal of sutures, excision of healed tissue on edges, and re-suturing the tongue together. Once healed, muscle control of the individual sides can be gained with practice if the split is sufficiently deep.
Can a split tongue grow back together?
Your doctor has to cut off a little bit of the inside edges of each half and then sew them back together [sources: Bonner; Loftus]. So while splitting your tongue may in fact be reversible, it's probably best if you consider it a permanent procedure.
Can you fix a split tongue?
Cosmetic Surgery answer:
It is possible to fix a tongue that is split and this would normally be done by a maxillo-facial surgeon. They tend to specialise in tongues and other areas inside the mouth and I think would be the best person to see your friend.