EXCLUSIVELeAnn Rimes is suing her dentist, claiming he botched up her mouth so bad ... it's messing up her career.
In the lawsuit ... obtained by TMZ ... Rimes claims she went to Dr. Duane C. McKay for various dental work over 3 years. Some of the work included upper front veneers and crowns that the dentist promised would address her TMJ-related pain as well as improve her appearance.
Rimes claims rather than helping, the dentist messed her mouth up bad, causing tremendous pain and bleeding. Back in October, she tweeted, "I feel like I got hit in my right side of my face with a baseball bat."
Rimes says she's had to undergo 9 root canals and bone grafting. She's also had a temporary bridge and needed physical therapy as well.
Rimes says in the suit she will have a "permanent cosmetic deficiency."
Rimes says the dental work is so bad it has been screwing with her career ... impeding her ability to perform.
In her malpractice lawsuit, LeAnn is seeking unspecified damages for physical, emotional and psychiatric injuries. She also wants money for loss of past and future earnings.