Tooth fairy

The Tooth Fairy is a fantasy figure of early childhood in Western and Western-influenced cultures. The folklore states that when children lose one of their baby teeth, they should place it underneath their pillow or on their bedside table and the Tooth Fairy will visit while they sleep, replacing the lost tooth with a small payment.
The tradition of leaving a tooth under a pillow for the Tooth Fairy or another fantasy figure to collect is practised in various countries.
Origins.
In Northern Europe, there was a tradition of "tand-fé" or tooth fee, which was paid when a child lost their first tooth. This tradition is recorded in writings as early as the Eddas (c. 1200), which are the earliest written record of Norse and Northern European traditions. In the Norse culture, children's teeth and other articles belonging to children were said to bring good luck in battle, and Scandinavian warriors hung children's teeth on a string around their necks.
The reward left varies by country, the family's economic status, amounts the child's peers report receiving and other factors. A 2013 survey by Visa Inc. found that American children receive $3.70 per tooth on average. According to the same survey, only 3% of children find a dollar or less and 8% find a five-dollar bill or more under their pillow.
During the Middle Ages, other superstitions arose surrounding children's teeth. In England, for example, children were instructed to burn their baby teeth in order to save the child from hardship in the afterlife. Children who did not consign their baby teeth to the fire would spend eternity searching for them in the afterlife. The Vikings, it is said, paid children for their teeth. Fear of witches was another reason to bury or burn teeth. In medieval Europe, it was thought that if a witch were to get hold of one's teeth, it could lead to them having total power over them.
The modern incarnation of these traditions into an actual Tooth Fairy has been traced to a 1908 "Household Hints" item in the "Chicago Daily Tribune":
Appearance.
Unlike Father Christmas and, to a lesser extent, the Easter Bunny, there are few details of the Tooth Fairy's appearance that are consistent in various versions of the myth. A 1984 study conducted by Rosemary Wells revealed that most, 74 percent of those surveyed, believed the Tooth Fairy to be female, while 12 percent believed the Tooth Fairy to be neither male nor female and 8 percent believed the Tooth Fairy could be either male or female. When asked about her findings regarding the Tooth Fairy's appearance, Wells explained: "You've got your basic Tinkerbell-type Tooth Fairy with the wings, wand, a little older and whatnot. Then you have some people who think of the tooth fairy as a man, or a bunny rabbit or a mouse." One review of published children's books and popular artwork found the Tooth Fairy to also be depicted as a child with wings, a pixie, a dragon, a blue mother-figure, a flying ballerina, two little old men, a dental hygienist, a potbellied flying man smoking a cigar, a bat, a bear and others. Unlike the well-established imagining of Santa Claus, differences in renderings of the Tooth Fairy are not as upsetting to children.
Depiction on coins and currency.
Starting in 2011, the Royal Canadian Mint began selling special sets for newborn babies, birthdays, wedding anniversaries, "Oh Canada" and the Tooth Fairy. The Tooth Fairy quarters, which were issued only in 2011 and 2012, were packaged separately.
In 2020, the Royal Australian Mint began issuing “Tooth Fairy kits” that included commemorative $2 coins. 
Belief.
Belief in the Tooth Fairy is viewed in two very different ways. On the one hand, children believing is seen as part of the trusting nature of childhood. Conversely, belief in the Tooth Fairy is frequently used to label adults as being too trusting and ready to believe anything.
Parents tend to view the myth as providing comfort for children in the loss of their tooth. Research finds that belief in the Tooth Fairy may provide such comfort to a child experiencing fear or pain resulting from the loss of a tooth. Mothers especially seem to value a child's belief as a sign that their "baby" is still a child and is not "growing up too soon". By encouraging belief in a fictional character, parents allow themselves to be comforted that their child still believes in fantasy and is not yet "grown up".
Children often discover the Tooth Fairy is imaginary as part of the 5- to 7-year shift, often connecting this to other gift-bearing imaginary figures (such as Santa Claus and the Easter Bunny).
Author Vicki Lansky advises parents to tell their children early that the tooth fairy pays a whole lot more for a perfect tooth than for a decayed one. According to Lansky, some families leave a note with the payment, praising the child for good dental habits.
Research findings suggest a possible relationship between a child's continued belief in the Tooth Fairy (and other fictional characters) and false memory syndrome.
Related myths.
The Ratoncito Pérez (or Ratón Pérez, "Pérez Mouse" in English) is a figure popular in Spanish and Hispanic American cultures, similar to the Tooth Fairy, originating in Madrid in 1894. As is traditional in some English-speaking countries, when a child loses a tooth it is customary for them to place it under the pillow, so that Ratoncito Pérez will exchange it for a gift. The tradition is almost universal in Spanish cultures, but takes different forms in different areas. He is known as "Ratoncito Pérez" in Spanish speaking countries, with the exception of some regions of Mexico, Peru and Chile, where he is called "el Ratón de los Dientes" (The Tooth Mouse), and in Argentina, Venezuela, Uruguay and Colombia, he is known simply as "El Ratón Pérez". The Ratoncito Pérez was used by Colgate marketing in Venezuela and Spain.
In Italy, the Tooth Fairy ("Fatina dei denti") is also often replaced by a small mouse, named "Topolino". In some areas the same role is held by Saint Apollonia, known as "Santa Polonia" in Veneto. (Saint Apollonia's legendary martyrdom involved having her teeth broken; she is frequently depicted artistically holding a tooth and is considered the patron saint of dentistry and those with toothache and dental problems.)
In France and French-speaking Belgium, this character is called "la petite souris" ("the little mouse"). From parts of Lowland Scotland comes a tradition similar to the fairy mouse: a white fairy rat who purchases children's teeth with coins.
In Catalonia, the most popular would be "" (little angels) and also "Les animetes" (little souls) and as in the other countries, the tooth is placed under the pillow in exchange of a coin or a little token.
In the Basque Country, and specially in Biscay, there is "Mari Teilatukoa" (Mary from the roof), who lives in the roof of the baserri and catches the teeth thrown by the children.
In Japan, a different variation calls for lost upper teeth to be thrown straight down to the ground and lower teeth straight up into the air; the idea is that incoming teeth will grow in straight.
In South Korea, the common practice is to throw both upper and lower teeth on the roof. The practice is rooted around the Korean national bird, the magpie. It is said that if the magpie finds a tooth on the roof, it will bring good luck or a gift like the Western Tooth Fairy. Some scholars think the myth derived from the word 까치(Ka-chi) which was a middle Korean word for magpies that sounds similar to "new teeth", or because of the significance of magpies in Korean mythology as a messenger between gods and humans.
In Middle Eastern countries (including Iraq, Jordan, Egypt and Sudan), there is a tradition of throwing a baby tooth up into the sky to the sun or to Allah. This tradition may originate in a pre-Islamic offering, and dates back to at least the 13th century. It is also mentioned by Izz bin Hibat Allah Al Hadid in the 13th century.
In popular culture.
In the 2010 film "Tooth Fairy", Dwayne Johnson plays as the titular character. The 2012 sequel stars Larry the Cable Guy.
A 2006 horror film, "The Tooth Fairy", features an evil Tooth Fairy. 
A killer nicknamed “The Tooth Fairy” (because of his nocturnal crimes) is featured in “Red Dragon,” part of the Hannibal Lecter franchise by Thomas Harris. He appears in the 1981 novel and the 1986 and 2002 movie adaptations. 
In episode 2 of "The Irregulars," a 2021 series on Netflix, the myth of the tooth fairy is an integral part of the plot. 