I have these white blisters in my mouth my dentist said there burns from using peroxide they keep peeling and coming back is that normal?

White blisters: Mouth lesions arise for different reasons: viral infections, fungal infections, trauma, gum disease, oral cancer, systemic infections. Any lesion in the mouth that does not heal in 7-10 days should be investigated further and probably biopsied.

Depends: Depends upon the time frame, duration, frequency and severity. If it has been a while since using the peroxide, then i would search for another cause of the blisters and possibly get a second opinion and/or a biopsy or other tests.