NATIONAL--The American Dental Association is looking into the safety of foreign and domestically produced dental crowns and other dental prostheses.

This comes after some media investigations found that bridges, crowns and fillings have been coming to the U.S. tainted with lead.

The A.D.D says until their investigation is complete, patients with concerns can ask their dentist these questions.

Do you make your own dental prostheses or buy them from a dental laboratory?

Where is the lab located?

If the lab is in a foreign country, does it provide written documentation that it is registered with the FDA?