I want safest material; any metal is out of the question, Pure Gold is a extremely soft substance, I have some 999 pure gold jewelry, you can mould it like rubber; so gold has to be mixed with other metals to make it hard.
According to Dr Clark & the book' Tooth Truth' all metals in the body & mouth disrupt energies & create a battery in the mouth which interrupts the brain signals (communication with the body). Besides; all metals are hiding places for parasites & germs & fungus etc.