Will a silver crown that has fallen out and opened up be reused?

My #14 molarcrown came open when I blew on it to clean out some "debris". It looked like a little crab! I quickly put it back tog. I saw a dentist the next day; told his hygienist what happened. She could not make it reopen.Do silver crowns somehow reseal themselves? Will I get decay if a crack is still there?if decay forms, how long will that take to show up and what are the symptoms? It wad decided to reglue the crown in place. Thank you for your very kind response.