Peace be upon you. Is it permissible for a woman to cover her teeth with gold?

There is no objection to a woman covering her teeth with gold. The basic principle is that gold is permissible for women, based on the Prophet's (peace and blessings be upon him) saying: "Wearing silk and gold is forbidden for the males of my Ummah and permissible for their females." Scholars have only made an exception for what goes beyond the norm to the extent of extravagance.