Metal Fillings and Natural Toothpaste

My wife has been using natural toothpaste that she makes herself for about a year or two now. Recently she has been tasting metal in her mouth on the side of her metal filling. She is now paranoid about the filling falling out due to her toothpaste. Is that a possibility? Her toothpaste is made using neem bark, cinnamon, peppermint, xylitol, and baking soda.