My son lost his first tooth yesterday and the Tooth Fairy visited our home for the first time last evening. She left a few gold dollar coins and some sparkly dust from her wings. Needless to say the magic in the eyes this morning from both kids was priceless. I wish it would last forever. Unfortunately it won't. The 6 year old will find out eventually and will want to tell his younger siblings.
My concern is how to keep the magic alive for the young ones once the secret is out. Are baby brothers and sisters doomed to grow up real fast?

See if you can get him to participate. Explain that he won't be able to "help" if he tells. My parents did this with me for Santa. Presents arrived while we were at the Chirstmas Eve service at church. Truth is that mom "did dishes" while we toured the neighborhood Christmas Lights. Just enough time to load the dishwasher and unload prepped bags onto chairs and under the tree. I was invited to "help with dishes" right before I knew what was up. Since I was "in on it" I didn't care a bit. I'd think this would work for the Tooth Fairy, too. Covert Tooth Operations. What could be cooler?