I've had this trick in my repertoire for years because it's portable and impromptu. I coincidentally
wound up with two of them which turned out perfect for enhancing the effect. When I decide to
perform this, I discreetly place one of the other coin pieces from my back up into my mouth which
can be loaded there while conversing and even eating and drinking if you're careful. When ready to
perform, after the bite is taken out of the coin, I can produce this extra piece on my tongue for
displaying to the spectator which totally convinces them you have indeed taken a bite out of the
coin.
When restoring the coin, just park the extra piece back under your tongue and "dispose" it
later when convenient.
As an aside, replacement bands can easily be obtained at your friendly
orthodontist at probably no cost to you. Over time, they will wear out or break. Hope these ideas
help