Baby Teeth

Baby Teeth

Also called: Deciduous Teeth, Primary Teeth, Deciduous Dentition

Reviewed By:
Kenneth Cheng, D.D.S.


Baby teeth, more accurately called primary teeth or deciduous teeth, are a person’s first set of teeth. They begin to form during the first trimester of pregnancy (first 12 weeks) and begin to emerge (erupt) through an infant’s gums around 6 months of age. All twenty primary teeth are typically fully erupted by the time a child is 3 years old and are later replaced by 32 permanent teeth.

Primary teeth have several functions. They help with biting and chewing, which contributes to good nutrition, and are crucial to a child’s ability to speak. They serve as a guide for permanent teeth to erupt and grow while maintaining the space. They also make a child look more attractive by supporting the shape of the face.

Proper dental hygiene is important for primary teeth, even though they eventually will be replaced by permanent teeth. Poor maintenance of baby teeth can cause them to fall out early, which in turn can cause permanent teeth to erupt prematurely and not in correct position.

If teeth are discolored when they erupt, it might indicate an underlying medical problem. Like permanent teeth, primary teeth are also vulnerable to plaque, a clear film that sticks to teeth and attracts bacteria and sugar. This can lead to cavities. Primary teeth are vulnerable to various injuries that can cause them to chip, fracture or completely come loose.

Proper care can help avoid many of the problems that sometimes affect primary teeth. After primary teeth begin to appear, they can be brushed with a soft children’s toothbrush. According to the American Dental Association (ADA), toothpaste should not be used until the child is 2 years old. As soon as two teeth erupt next to each other, they should be flossed at least once daily. Children who take good care of their teeth form habits that help keep their teeth healthy for a lifetime. Proper maintenance and care of all teeth remains crucial to maintaining good dental health.

About baby teeth

Baby teeth, more accurately known as primary teeth or deciduous teeth, are the first of two sets of teeth that people develop during their lifetimes. They begin to form during the first trimester of pregnancy and have fully formed by the time an infant is born. However, primary teeth usually remain hidden under the gums until they begin to emerge (erupt) between 5 months and 8 months of age. This process is known as teething. 

A human tooth is composed of several parts:

  • Crown. Part of the tooth that is visible above the gum line.
  • Enamel. The hard, translucent outer shell that covers the crown. The enamel is hard enough to handle the strain of a lifetime of biting, chewing and grinding. It also protects the tooth from bacteria and changes in temperature when eating hot or cold foods. Nonetheless, it is brittle and may crack or chip.
  • Root. Part of the tooth that pushes into the upper (maxilla) or lower (mandible) jawbone. Each root has a tiny opening at the bottom called the apical foramen. Blood vessels and nerves enter the root through this space.
  • Cementum. Hard shell that covers the root and attaches to fibers that fasten the root to the jawbone.
  • Dentin. Layer of the tooth found beneath the enamel and the cementum. It makes up most of the tooth’s structure and is responsible for the tooth’s color. It typically has a whitish to yellowish hue.
  • Pulp. Located beneath the dentin at the core of the tooth. It is made up of blood vessels, nerves and connective tissue. The blood supply of the pulp provides the nutrients that keep the tooth alive. The pulp is made up of two parts. The pulp chamber is found in the crown of the tooth. The root canal is the part of the pulp located in the root of the tooth, where blood vessels and nerves enter the tooth.

Twenty primary teeth – eight incisors (four front teeth on both the upper and lower jaw), four canines (located in the front of the jaw behind the incisors) and eight molars (larger teeth in the back of the mouth) – typically erupt by the time a child is 3 years old. Eruption of the lower teeth generally precedes eruption of the top teeth. Eruption times for girls are generally earlier than those for boys.

The following schedule for the top primary teeth was established by the American Dental Association (ADA):

  • Central incisor: 8 months to 12 months
  • Lateral incisor: 9 months to 13 months
  • Canine (cuspid): 16 months to 22 months
  • First molar: 13 months to 19 months
  • Second molar: 25 months to 33 months

Eruption of the bottom primary teeth occurs as follows:

  • Central incisor: 6 months to 10 months
  • Lateral incisor: 10 months to 16 months
  • Canine (cuspid): 17 months to 23 months
  • First molar: 14 months to 18 months
  • Second molar: 21 months to 31 months

The first primary teeth to emerge are usually the bottom two incisors, followed by the top four incisors and then the rest of the bottom incisors. After the incisors the rest of the primary teeth begin to fill the mouth, usually with two developing at a time. The roots of primary teeth are 50 percent formed when eruption first begins, and roots are completed by the time a child is between the ages of 18 months and 3 years.

Primary teeth have several roles. They help with biting and chewing, and are crucial to a child’s ability to speak. They may also make a child appear more attractive. Finally, primary teeth serve as a guide for permanent teeth. For this reason, primary teeth usually have more space between them to allow permanent teeth more room to erupt.

Primary teeth are smaller and whiter than permanent teeth. Some of the other ways in which primary teeth differ from permanent teeth include:

  • Crowns are shorter in primary teeth
  • Enamel depth is more consistent and thinner in primary teeth
  • Pulp chambers of primary teeth are larger relative to the size of the tooth
  • Roots are longer and more slender in primary teeth

Eventually, a child’s primary teeth begin to fall out. The middle teeth in front (incisors) typically fall out at age 6. Molars in the back are shed between the ages of 10 and 12. By age 13, children usually have their permanent teeth.

A total of 32 permanent teeth replace the original 20 primary teeth. Meanwhile, permanent first and second premolars (bicuspids) replace the primary first and second molars and permanent incisors and canines replace primary incisors and canines. The permanent molars which grow towards the back of the mouth do not replace baby teeth. This is why there are more teeth in permanent dentition.

Potential problems with baby teeth

Although a child’s baby teeth, or primary teeth, eventually will be replaced by permanent teeth, it is important to care for these initial teeth. When primary teeth emerge, they should be off-white or ivory in color. Teeth that erupt with a black tint or another color usually indicate an underlying problem. Most often, this is the result of plaque growing on the teeth due to a build-up of bacteria in the child’s mouth. Liquid medications containing iron, some antibiotics and certain supplemental vitamins also can cause this effect. Other potential causes of discoloration include:

  • Chronic illness or recurrent fevers
  • Excessive fluoride, which may cause bright white spots (fluorosis)
  • Injury to the teeth, which may cause pink or grayish discoloration
  • Jaundice in newborns, which may cause yellowish or greenish tint
  • Use of the antibiotic tetracycline by the mother during pregnancy

Poor maintenance of primary teeth can result in premature loss either naturally or by extraction. This can cause a change in the eruption schedule of the permanent teeth, which may lead to space problems for proper eruption. The permanent teeth may erupt crooked and misaligned. 

Primary teeth are also vulnerable to dental plaque, a clear film that sticks to teeth and attracts bacteria and sugar. As the bacteria feed on the sugar, they are broken down into acids that eat into the enamel of the teeth. This causes cavities in the teeth, which can be painful. In addition, plaque can cause gums to become red, swollen and sore. This condition is known as gingivitis, or gum disease. 

The first risk to a child’s primary teeth often comes in the form of baby bottle tooth decay (baby bottle syndrome or bottle mouth). This condition results from leaving a bottle in a baby’s mouth for long periods of time while the baby sleeps. Sugars from milk or juices that bathe and remain on the teeth for hours at a time begin to eat away at the enamel. Pocked, pitted or discolored front teeth are signs of the condition. In its most extreme form, this condition can lead to a need to pull a baby’s front teeth until permanent teeth grow in. As a rule, parents or caregivers should only allow a baby to have a bottle during meals, and to fill the bottle only with water if it is used at night.

As children grow older, the primary teeth remain at high risk for cavities. Cavities are one of the most common chronic conditions among children in the United States, according to the American Academy of Pediatrics. Among 3-year-olds, 18.7 percent have at least one tooth with a cavity that has yet to be treated. By the time a child is 8 years old, 51.6 percent have an unfilled cavity or at least one filling. Children who were born prematurely or who had a low birth weight are at increased risk for cavities. Other factors that increase the risk of cavities include:

  • History of ongoing health care needs
  • White spots or brown areas on teeth
  • Failure to regularly see the dentist
  • Inadequate brushing and flossing regimen
  • Poor socioeconomic status
  • Diet that includes too many sugary foods and drinks

Primary teeth are also vulnerable to injuries that can cause them to chip, fracture or completely come loose. Usually, an injury causes baby teeth to loosen rather than fracture. These injuries often occur as the result of falls, mishaps during play or accidents during athletics. If a child suffers an injury to the gums or a baby tooth that causes bleeding, parents may be advised to run cold water over a piece of gauze and apply pressure gently to the injury site. Sucking on an ice pop may be recommended to reduce swelling until the child can see a dentist.

Baby teeth that are knocked out do not require special care after they come loose, unlike permanent teeth, because they cannot be reimplanted. Reimplanting a baby tooth can damage developing permanent teeth and often results in death of the pulp.

Nonetheless, a child’s tooth injury usually requires a visit to a healthcare professional. In many cases, consulting the dentist is the best option. However, a visit to a hospital emergency room may be necessary if the child has suffered a blow to the head, which can be life-threatening, or an injury to another body part. In some cases of primary tooth loss, a dentist may use a space maintainer to keep the area open until the permanent tooth erupts.

Caring for baby teeth

Even before teeth appear, the infant’s gums should be wiped with a damp washcloth after each feeding. This can help prevent the build-up of bacteria that can discolor primary, or baby, teeth. After teeth begin to appear, they can be brushed with a soft children’s toothbrush. The brush can be made softer by soaking it in warm water for several minutes. Gauze can be rubbed over the teeth instead of using a toothbrush. This should be done at the end of the day to help prevent tooth decay. As soon as two teeth erupt next to each other, they should be flossed at least once daily.

Initially, parents or caregivers should be cautious about using toothpaste on their child’s primary teeth. Young children (especially those under age 6) tend to swallow toothpaste rather than spit it out. Too much fluoride can disrupt the formation of enamel in permanent teeth, a problem called fluorosis, which can cause minor discoloration and surface irregularities.

Children generally do not have the dexterity needed to thoroughly brush and floss before the age of 6 or 8. While it is often a good idea to let them practice, parents or caregivers are urged to remember that children require adult assistance to make sure teeth are properly brushed. It is recommended that parents or caregivers take their child for the first visit to the dentist at about age 1.

Children who take good care of their teeth form habits – such as eating a well-balanced diet, not overindulging in sweets, and regularly brushing and flossing – that can keep their teeth healthy for a lifetime. Proper maintenance and care of teeth remains crucial for maintaining good dental health.

Questions for your doctor regarding baby teeth

Preparing questions in advance can help patients to have more meaningful discussions regarding their conditions. Patients may wish to ask their doctor the following questions related to baby teeth:

  1. Should I be worried if my child’s baby teeth do not emerge by 8 months of age?
  2. What should I do if my child’s teeth erupt discolored?
  3. How old should my child be before I start using toothpaste when brushing his/her teeth?
  4. How old should my child be before I allow him/her to practice brushing and flossing?
  5. What should I do if my child’s teeth are injured?
  6. If my child loses a tooth, how will you help ensure that the emerging permanent teeth are not affected?
  7. What foods should my child avoid to help prevent tooth decay?
  8. What are some tips for encouraging my child to properly care for his/her teeth?
  9. I know some medications cause tooth discoloration. Is my child vulnerable to this effect?
  10. What are my child’s treatment options if he/she has baby bottle tooth decay?
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