I have two points to bring out.
One is that nowadays, some people have their children's 4 top MILK TEETH banked with a special Science Lab, one is BioEden Baby Tooth Stem Cell Bank. Believe it or not, they are now finding that a child's baby teeth are the most important resources in getting LIFE SAVING STEM CELLS, similar to the Umbillical CORD BLOOD. For a fee, the company extracts the stem cells from the tooth for future use and preserves it indefinately. Should the child ever become sick in the future, it can literally be a life saver to have the stem cells... That being said... if you don't want to save the tooth for SCIENCE or medical purposes...
There is the TOOTHFAIRY's BABY BANK TOOTH... it is a TOOTH SHAPED BANK and surrounding it, are little holes to put all of the child's teeth IN ORDER, displayed for each tooth. Here is the link for it that I found online. http://www.tfairy.com/toothbank.html
As for my own personal experience with my kids, now grown...I was given a little red plastic case the size of a dime or penny, from my child's dentist. I put my child's tooth in that. When their teeth fell out, we put the tooth in the case, and I placed that in a little toothfairy pillow with a built-in pocket. It was the size of a 3 x 5 index card. I told my kids that the toothfairy would leave them money for the tooth. My daughter used to write a note with questions to the tooth fairy...(For some reason, she thought it was "Princess Di" back then in 1981-82.) I would write her a note back, disguising my handwriting, and answer all her questions. With slight of hand, like a Magician, I would pretend that I was slipping HER folded note into the Pillow Pocket, WITH the red tooth case, when I was actually palming her note and slipping in MY answers to the questions, with a folded bill or coins inside! I would also inspect the plastic box just before putting it into the pillow pocket, telling her I was making sure the tooth was secure, and would remove just the tooth without her knowing. I would place the tiny pillow under her bed pillow, informing her not to touch it or the tooth fairy would not come. By next morning, she would find the tooth missing, the note written by the tooth fairy, with money inside, and get all excited. This way I did not have to worry about being CAUGHT removing the tooth and replacing with payment, as she was a light sleeper. I STILL have the red case that the dentist gave me, with her tooth in it. I kept both of my kids first teeth, to this day. She is 32 and my son is 23.