Women aren't allowed to show their hair to non-mahrams. What about wigs?

Women aren't permitted to show their hair to non-mahrams. Lets say that there was a wedding, and lots of non-mahram men were present. Will the woman be allowed to wear a wig (and style it) so she does not show her hair to non-mahrams? Not necessarily at a wedding, but just in public. Can a woman wear a wig to cover her hair instead of some sort of scarf (hijab)?