Tooth Development
Because a baby's teeth form in the jaw, a tooth must grow through bone before pushing through the gum. It's not uncommon for the area of gum where a tooth is coming through to become red and swollen. This goes away after the tooth comes in. Once a baby tooth has erupted through the gum, it takes an average of 18 months for the roots of the tooth to form. The first teeth to come in are usually the two lower middle teeth. These teeth generally come in when a baby is about 6 months old. However, some babies get their first tooth when they are as young as 3 months. Because teething age varies, other children may not get that first tooth until they are 18 months old. Heredity plays a key role. The age at which teething begins often depends on how old Mom and Dad were when they got their first tooth. Children get 20 primary teeth in all. Most have come in by the time a child is 4. Even so, the time frame and order in which the teeth come in can differ.
Prenatal
A baby's first teeth begin to form prior to birth. According to the American Dental Association, what a woman eats during her pregnancy affects the development of her unborn child's teeth. Tooth development begins between the third and sixth months of pregnancy. For this reason, pregnant women should eat a well-balanced diet that includes adequate amounts of calcium and phosphorous, protein and vitamins A, C and D. These are the nutrients needed for the fetus to develop healthy teeth. Although tooth enamel begins to form intrauterine, the enamel does not complete hardening until several months after birth.
Function
When the crown of a tooth first breaks through the gum, it's covered by what is known as enamel cuticle, which is formed when the tooth is developing. This thin layer of film covers a newly erupted tooth. Chewing and tooth brushing eventually wear away this coating on young tooth enamel. The first front teeth that come in are sharp; they're meant for biting and not chewing. The back teeth are the teeth for chewing. A baby's first molars start to come in at approximately 12 to 16 months of age. The second molars, which can be painful when coming in, don't begin to erupt until sometime around a child's second birthday. The upper and lower cuspids or canines come in after the first molars but before the second molars, usually when a baby is about 1 1/2 years old.
Positioning
Maintaining the health of a child's primary teeth is necessary for permanent teeth to develop healthy. The lips, gums and cheeks affect how teeth are positioned and spaced. Proper alignment of primary teeth generally leads to permanent teeth lining up correctly in the mouth. Although the tongue pushes outward on the teeth, the lips and cheeks provide an inward balance. Primary teeth hold the space for the permanent teeth so that they come in correctly positioned. Primary teeth also help the upper and lower jawbones and muscles to develop normally.
