hello! i am a dental hygienist so i've seen lots of tongues :P
there's many different things that it could be. do you remember if your dentist gave you a reason or diagnosis for it? what was the stuff to swish with and what was supposed to happen?
do you experience dry mouth? many people have dry mouth and many medications can be the cause, if this is a possibility you may never be able to fully rid yourself of the tongue gunk.
do you have bad breathe? do you drink a lot of coffee?
there's a million things that it could be.
not to sound gross, but a picture would be really helpful.
good luck!
-Michelle
