There are a lot of reasons why the Tooth Fairy might choose not to accept a tooth, and this letter can be used to list them.
Text of the letter:
Dear Susie,
This is a form letter notifying you that your visitation from The Tooth Fairy has been rejected for the following reason(s):
The tooth had a cavity/decay
The tooth was not properly cleaned (plaque)
The tooth was, upon further inspection, a corn kernel
Your room is too messy for The Tooth Fairy to enter
Your recent behavior has upset The Tooth Fairy
You were overheard, by credible sources, denying the existence of The Tooth Fairy
You stole or bought this tooth from your sibling/a friend/the black market
Your antics at that last dental appointment were appalling
Questions or comments about this rejection may be put into writing and left under your pillow. A Tooth Fairy representative will collect it (if your room is clean enough) and issue a response in 3 to 5 business days.
The Tooth Fairy