Yes! If you don’t have any white vinegar or baking soda handy, you can certainly use toothpaste to clean a burnt iron.
To do this, rub white toothpaste onto the soleplate and then leave it for a minute before wiping it off with a clean microfibre cloth.
Then, place your iron onto another cloth and fill up the water tank. Finish by turning it on and letting it steam for a few minutes.