In The Mask, the oversize teeth were not meant to be used when Jim Carrey speaks, but he taught himself to talk with them to make his character more wacky. : r/MovieDetails
Jim Carrey reveals he WOULD be happy to portray The Mask again but only with a 'visionary filmmaker' | Daily Mail Online
The Violent, Gory, and Gross Origins of Jim Carrey's 'The Mask' - The Ringer