Dental xrays are ok during pregnancy. They are a very low dose, are pointed directly at your head, and your abdomen is covered with a lead apron (my dentist even used 2 apron just to be safe). I was told this by multiple sources, including Mothersafe.

I wouldn't worry hun. Enjoy your super-clean mouth!
My dentists said that too. But they like to err on the side of caution and they don't do them on pregnant women.