Deciduous teeth, otherwise known as baby teeth, temporary teeth, milk teeth, and
now more commonly primary teeth, are the first set of teeth in the growth
development of humans and other diphyodont mammals. They develop during
the embryonic stage of development and erupt—that is, they become visible in
the mouth—during infancy. They are usually lost and replaced by permanent
teeth, but in the absence of permanent replacements, they can remain functional
for many years. Primary dentition stage
Primary teeth start to form during the embryo phase of pregnancy. The
development of primary teeth starts at the sixth week of tooth development as
the dental lamina. This process starts at the midline and then spreads back
into the posterior region. By the time the embryo is eight weeks old, there are
ten buds on the upper and lower arches that will eventually become the primary
dentition. These teeth will continue to form until they erupt in the mouth. In
the primary dentition there are a total of twenty teeth: five per quadrant and
ten per arch. The eruption of these teeth begins at the age of six months
and continues until twenty-five to thirty-three months of age during the
primary dentition period. Usually, the first teeth seen in the mouth are the
mandibular centrals and the last are the maxillary second molars.
The primary dentition is made up of central incisors, lateral incisors,
canines, first molars, and secondary molars; there is one in each quadrant,
making a total of four of each tooth. All of these are gradually replaced with
a permanent counterpart except for the primary first and second molars; they
are replaced by premolars. These are designated in the Universal Tooth
Designation System by the capital letters A through T. The replacement of
primary teeth begins around age six, when the permanent teeth start to appear
in the mouth, resulting in mixed dentition. The erupting permanent teeth
cause root resorption, where the permanent teeth push on the roots of the
primary teeth, causing the roots to be dissolved by odontoclasts and become
absorbed by the forming permanent teeth. The process of shedding primary teeth
and their replacement by permanent teeth is called exfoliation. This may last
from age six to age twelve. By age twelve there usually are only permanent
teeth remaining. Teething age of primary teeth:
Central incisors : 6–12 months Lateral incisors : 9–16 months
First molars : 13–19 months Canine teeth : 16–23 months
Second molars : 22–33 months Role
Primary teeth are considered essential in the development of the oral cavity by
dental researchers and dental professionals. The permanent teeth
replacements develop from the same tooth germs as the primary teeth, which
provide guides for permanent teeth eruptions. Also the muscles of the jaw
and the formation of the jaw bones depend on the primary teeth to maintain
proper spacing for permanent teeth. The roots of primary teeth provide an
opening for the permanent teeth to erupt. The primary teeth are also needed
for proper development of a child's speech and chewing of food.
Cultural traditions In almost all European languages the
primary teeth are called "milk teeth". In the United States and Canada, the
term "baby teeth" is common. In some Asian countries they are referred to as
"fall teeth" since they will eventually fall out.
Various cultures have customs relating to the loss of deciduous teeth. In
English-speaking countries, the tooth fairy is a popular childhood fiction
that a fairy rewards children when their baby teeth fall out. Children typically
place a tooth under their pillow at night. The fairy is said to take the
tooth and replace it with money or small gifts while they sleep. In some places
in Australia, Sweden and Norway, the children put the tooth in a glass of
water. In medieval Scandinavia there was a similar tradition, surviving to the
present day in Iceland, of tannfé, a gift to a child when it cuts its first
tooth. Other traditions are associated with
mice or other rodents because of their sharp, everlasting teeth. The character
Ratón Pérez appears in the tale of The Vain Little Mouse. A Ratoncito Pérez was
used by Colgate in marketing toothpaste in Venezuela and Spain. In Italy, the
Tooth Fairy is also often replaced by a small mouse. In France and in
French-speaking Belgium, this character is called la petite souris. From parts
of lowland Scotland comes a tradition similar to the fairy mouse: a white
fairy rat who purchases the teeth with coins.
Several traditions concern throwing the shed teeth. In Turkey, Cyprus, Mexico,
and Greece, children traditionally throw their fallen "milk teeth" onto the roof
of their house while making a wish. Similarly, in some Asian countries, such
as India, Korea, Nepal, Philippines, and the Vietnam, when a child loses a tooth,
the usual custom is that he or she should throw it onto the roof if it came
from the lower jaw, or into the space beneath the floor if it came from the
upper jaw. While doing this, the child shouts a request for the tooth to be
replaced with the tooth of a mouse. This tradition is based on the fact that the
teeth of mice grow for their entire lives, a characteristic of all rodents.
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. Some parts of China follow a
similar tradition by throwing the teeth from the lower jaw onto the roof and
burying the teeth from the upper jaw underground, as a symbol of urging the
permanent teeth to grow faster towards the right direction.
The Sri Lankan tradition is to throw the milk teeth onto the roof or a tree in
the presence of a squirrel. The child then tells the squirrel to take the old
tooth in return for a new one. In Pakistan, children bury their teeth
on their roof or in their garden in the hopes of a new sibling.
In some parts of India, young children offer their discarded baby teeth to the
sun, sometimes wrapped in a tiny rag of cotton turf. In Assam state of India,
children throw their milk teeth to the roof of their house and urge mouse to
take it and exchange with its teeth. The tradition of throwing a baby tooth
up into the sky to the sun or to Allah and asking for a better tooth to replace
it is common in Middle Eastern countries. It may originate in a
pre-Islamic offering and certainly dates back to at least the 13th century, when
Izz bin Hibat Allah Al Hadid mentions it.
In premodern Britain, lost teeth were commonly burnt to destroy them. This was
partly for religious reasons connected with the Last Judgement and partly for
fear of what might happen if an animal got them. A rhyme might be said as a
blessing: See also
Permanent teeth Tooth development
Tooth eruption Tooth fairy
References External links
Primary dentition - Baby teeth chart Morphology and eruption time of primary
teeth.