Tooth, Thread, and a Doorknob

Abby's grandmothers (Grandma and Noni) both recommended that she tie a string around her loose tooth and a doorknob and shut the door. Well, Abby really wanted to try this. She insisted that we use white thread. We've tried several nights in a row, but the tooth just doesn't want to budge. (Or perhaps I simply don't know how to tie a piece of thread around a really little tooth!