My mom used to read outloud. She used to read magazine, newspapers, books and so on, just for the practice. She would do most of it in private, but as she got more comfortable, she started reading stories to us out of her magazines. It did take a few weeks, but now we cannot tell anything was done to her mouth.

practice, practice, practice. Read the street signs out loud in your car, the bulletin boards, the the highway signs. any bit of practice will help.