How can you get a cracked tongue smooth again?

Normal: Fissured tongue is a perfectly normal anatomic variation. It requires no treatment at all.

Cracked tongue: What is the reason and duration for your "cracked tongue"? Fissured tongue, a very common phenomenon will most likely not get "smooth" again, however, if you are experiencing "cracked tongue" due to vitamin deficiency, or nutritional deficiency that could conceivably be reversed.

Depends: Have you always had a "cracked" tongue or is this something that comes and goes. I would keep a diary of from day to day if symptoms constantly change. Either way, i would see a dentist and ask questions personally.