It is permissible to put veneers and the like on the teeth, for the purpose of protection and beautification, or to correct deformities. The presence of veneers on the teeth does not affect Wudu.

There is a concession allowing a woman to wear a wig if all of her hair has fallen out. If you wear a wig because of that, then you may wipe over it when doing wudu. However, you must take it off when doing ghusl, because it is obligatory to make the water reach all of the skin. For more, please see the detailed answer.