Teeth anatomy: Baby teeth (primary dentition)


An Introduction to Teeth

Children’s teeth play an important role in digestion and reserving spaces for permanent teeth. Children’s teeth are also known as primary teeth. Due to the smaller jaw size of a child, there are only 20 teeth in total. In comparison, there are 32 teeth in an adult’s mouth. Children are not born with teeth. Teeth usually begin to erupt from 10 months of age and finish around 29 months of age. The primary teeth consist of incisors (cutting teeth), canines (tearing teeth) and molars (grinding teeth). The tooth consists of a crown and root, and the tooth is composed of different materials that aid in strengtheningpreserving and maintaining its function. Purpose of Teeth

  • To breakdown food into smaller pieces to aid in the process of digestion.
    • Children have 20 teeth in their mouth.
    • There are 10 teeth on both the top and bottom jaw.
    • Each jaw consists of specific teeth, which are incisors (cutting teeth), canines (tearing teeth) and molars (grinding teeth).
  • From the midline of one side of each jaw consists of 2 incisors, 1 canine, and 2 molars. Maintains a space for permanent teeth to come through.

Classification and Location of Teeth

Primary Teeth Eruption Sequence

  • It begins around 10 months and ends around 29 months.
  • Specific eruption times are:
    • Incisors= 10 months (8-13 months).
    • Canines= 19 months (16-22months).
    • 1st Molars= 16 months (13-19 months).
  • 2nd Molars = 29 months (25-33 months).

Tooth Structure

  • The anatomy of the tooth consists of root (hidden in the gum) and crown (visible part of the tooth).
  • The root of the tooth functions as an anchor for the tooth and allows for blood and nerve supply to enter the tooth to maintain its viability.
  • The crown is the surface that allows for food breakdown as opposing teeth are brought together when chewing.
  • The crown and root consists of hard and soft tissue.
  • The hard tissue covering the crown is called enamel, a hard mineral surface, whereas the root is covered by cementum, a hard mineral surface, however, it is softer compared to enamel.
  • The next layer under both enamel and cementum is dentin, the main bulk of the tooth. Dentin is considered a hard tissue, however, it is much more porous than either of the other hard tissues to allow nutrients to be transferred through the tooth layers.
  • The next layer under dentin is the pulp tissue that is housed in a pulp cavity. The pulp cavity has a rich blood supply and nerve supply, which is essential for maintaining tooth health.
  • The root of the tooth is embedded in bone, which is covered in tissue called gingiva. The root is held in place by strands of tissue that originated from the surrounding bone and embedded into cementum. These strands of tissue are called periodontal ligaments.

The following chart shows when your child’s primary teeth (also called baby teeth or deciduous teeth) should erupt and shed. Eruption times vary from child to child.

As seen from the chart, the first teeth begin to break through the gums at about 6 months of age. Usually, the first two teeth to erupt are the two bottom central incisors (the two bottom front teeth). Next, the top four front teeth emerge. After that, other teeth slowly begin to fill in, usually in pairs — on each side of the upper or lower jaw — until all 20 teeth (10 in the upper jaw and 10 in the lower jaw) have come in by the time the child is 2 ½ to 3 years old. The complete set of primary teeth is in the mouth from the age of 2 ½ to 3 years of age to 6 to 7 years of age.

   Primary Teeth Development Chart  

  Upper Teeth  When tooth emerges  When tooth falls out  

  Central incisor 8 to 12 months 6 to 7 years  

  Lateral incisor 9 to 13 months 7 to 8 years  

  Canine (cuspid) 16 to 22 months 10 to 12 years  

  First molar 13 to 19 months 9 to 11 years  

  Second molar 25 to 33 months 10 to 12 years  

  Lower Teeth        

  Second molar 23 to 31 months 10 to 12 years  

  First molar 14 to 18 months 9 to 11 years  

  Canine (cuspid) 17 to 23 months 9 to 12 years  

  Lateral incisor 10 to 16 months 7 to 8 years  

  Central incisor 6 to 10 months 6 to 7 years  

  Other primary tooth eruption facts:

  • A general rule of thumb is that for every 6 months of life, approximately 4 teeth will erupt.
  • Girls generally precede boys in tooth eruption.
  • Lower teeth usually erupt before upper teeth.
  • Teeth in both jaws usually erupt in pairs — one on the right and one on the left.
  • Primary teeth are smaller in size and whiter in color than the permanent teeth that will follow.
  • By the time a child is 2 to 3 years of age, all primary teeth should have erupted.

Shortly after age 4, the jaw and facial bones of the child begin to grow, creating spaces between the primary teeth. This is a perfectly natural growth process that provides the necessary space for the larger permanent teeth to emerge. Between the ages of 6 and 12, a mixture of both primary teeth and permanent teeth reside in the mouth.

Why Is it Important to Care for Baby Teeth?

While it’s true that baby teeth are only in the mouth for a short period, they play a vital role. Baby teeth:

  • Reserve space for their permanent counterparts
  • Give the face its normal appearance.
  • Aid in the development of clear speech.
  • Help attain good nutrition (missing or decayed teeth make it difficult to chew, causing children to reject foods)
  • Help give a healthy start to the permanent teeth (decay and infection in baby teeth can cause damage to the permanent teeth developing beneath them)

To understand the problems that decaying baby teeth can cause permanent teeth, see Oral Health Problems in Children.

We love our patients and love to help them form healthy dental life that will last them a lifetime. For more information call us today to answer all of your questions so get an appointment.