i have a bad odor when I floss between my two crowns! Help

Hello there,A crown that does not fit the tooth perfectly can cause a buildup of bacteria, and any void in the crown margin can harbor odor-producing bacteria. If I were your doctor, I would inspect the margins of both crowns.  If nothing can be found, I would likely recommend removing one or both crowns, cleaning the underlying tooth, then placing a new crown. I would expect this to solve the issue of the smell.  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 is hard to give a reason without a full clinical picture and x-rays. It could be a crown margin that is open or overhang, decay, or a deep pocket. This odor is usually caused by a hidden area that is not reachable with cleaning. 

There
could be either decay on the root below the crown margin or a gap at the margin
of the crown. Either of these would be a more likely cause than the crown
material. If decay gets under a crown through a gap in the margin it’s a serious
problem that could cause you to need a root canal or even lose the tooth.

A bad odor between two crowns is definately not normal. It usually means that one or both of the crowns are leaking and bacteria is getting under the crown. The material that crowns are made of does not cause an odor. Bacteria cause odors. I suggest having a closer look taken of your crowns. It sounds like one or both may need replacement.

The odor could be due to food impaction between the crowns. If the contact between the crowns is not tight enough, then food and bacteria can get trapped between the crowns and wedged in the gums. Another reason could be if the crowns are defective or have open margins, which could also cause food/bacterial accumulation. I would recommend talking to your dentist about the issue.