Can they do a culture test to rule out or confirm the type of infection for proper treatment, like thrush, as Christine mentioned, but the biopsy may confirm this?? I have numb lip, chin and jaw area from a segmental mandibularectomy done in September wheby the the jaw nerve was cut. I believe some biopsies can be wrong based on inadequate sampling, handling/human error, experience. I think that's why when I wanted a consult a top CCC they wanted my original biopsy slides, and another, do their own confirmation for treatment by direct biopsy.
Good luck