We are ALWAYS losing the cap to the toothpaste. Today, I had enough and just glued it on with floss. Just take some floss and tie it to the toothpaste tip and glue (with hot glue) the other end to the top of the cap. It must be the top of the cap so when you twist the cap back on it won't get tangled. I know it might seem silly, but it really works for us.