Q. Our toddler has gray stains on her lower teeth. What causes this?

A. There are lots of possible reasons for gray-looking teeth. Did you take tetracycline or a similar antibiotic when you were pregnant? Doing so can affect the fetus's teeth and cause stains when they erupt.

The discoloration could also be due to trauma to the mouth. My eldest child, Michaela, did a face plant in the driveway when she was a toddler and had a gray front tooth until it was pulled later. Other possible culprits are poor dental hygiene (you should brush your daughter's teeth regularly as soon as they come in), food stains, past infections, and medications she's taken, such as liquid iron supplements. Some liver and blood diseases can also cause teeth to look gray. And while it's rare, problems with tooth enamel can sometimes be the explanation.

Bottom line: Talk to your doctor to figure out the cause. Together you can decide whether your daughter needs treatment and whether the stains can be removed.