I have had porcelain veneers for 21 years, and now suspect that a bacterial/fungal infection has formed underneath them.

Hello there,I would recommend seeing your dentist for a complete evaluation if you suspect that you have an infection underneath your veneers.  Veneer leakage allows bacteria to enter and form decay underneath the veneers.  If ignored, substantial tooth structure can be destroyed.  If you do in fact have an infection under your veneers, they'll need to be replaced. Good luck and I hope this helps. Follow me if you have more questions.Sarah Thompson, DMDSt. Louis, MO area (O'Fallon, IL)Real Self 100

It sounds as if you have not seen a dentist in a while. If that's the case, you should schedule an appointment with a dentist and have an comprehensive examination. They would be able to determine if anything is failing with your veneers.Douglas Jopling,  DDSDallas, TX area

You don't mention how you know that you are having bacterial leakage under your veneers. The only way to treat this situation is to remake your veneers. After 21 years you have definitely gotten a long life out of them.