If your crown has darkend a little what can you do to get them back to the natural color they were when you got them... .

It : It depends somewhat on the material that the crown is made of, but if it's not surface stain that can be polished off the usual remedy is to remake the crowns with an improved color. If the surface has been stained by food, coffee or smoking it is possible that polishing the stain off may improve the color.

One : One of the great things about modern dental materials is their color stability. One of the bad things about modern dental materials is their color stability. Truthfully, the only way to change the color of a crown is to make a new one.

Have : Have you teeth professionally polished to see if the darkening is due to surface staining. Otherwise, there is nothing you can do since porcelain doesnt change color. If the crowns were made of resin, then the staining is deeply embedded in the material and cannot be removed.