In many countries, including the United States, the tooth fairy is popular – somewhat similar to the Easter bunny or Santa Claus. According to the custom, if a young child loses one of their baby teeth, and puts the tooth under their pillow, the tooth fairy will visit while they sleep and replace the tooth with a small gift.
There is a website called toothfairy.org, which has descriptions of 22 children’s books about losing teeth and the tooth fairy that you can buy on Amazon. On another website, you can read about where children of other countries put their lost baby teeth.
There’s an old Disney family movie for free on YouTube called Toothless about a dentist who had to act as the tooth fairy so she could be admitted into Heaven. Remember that on YouTube, you can turn on Closed Captions to read the words while you watch.