Teething is the process by which an infant’s first set of teeth erupt (emerge) through the gums. This first set may be referred to as primary teeth, deciduous teeth or baby teeth. The teeth typically emerge in a set pattern and at predictable intervals of time, although there are variations. If an infant’s teeth erupt in a pattern that is not typical, there is not necessarily anything wrong.

Tooth development begins before birth. Early teeth are present in an infant’s jaw, under the gums, at birth. As the infant ages, they continue to develop until they are ready to emerge through the gums. The age at which this occurs varies widely from infant to infant and depends largely on family history. Rarely, a tooth or two may be present at birth or erupt within the first month. However, the first teeth usually appear some time between the ages of 3 months or 4 months and 8 months to 10 months. The average age that teething begins is 6 months but a child may reach an age of 12 months to 16 months before the first teeth erupt. When a tooth is coming in, the surrounding gum may be raised, swollen and discolored (red to purple). The primary teeth are smaller than the teeth in an older child or adult’s mouth, but similar in shape and appearance. For example, an emerging incisor may look like a small, white peg. An emerging molar, on the other hand, will appear as a small, relatively flattened surface. Once the tooth emerges, any swelling or discoloration tends to fade. In some cases, an erupting tooth may cause a small amount of bleeding.

The typical pattern in which the first set of teeth erupts is as follows:

1. Lower central incisors. The two middle teeth in the front of the jaw are usually the first to emerge.
   
   
2. Upper central and lateral incisors. The four teeth in the front on the top tend to erupt a month or two after the lower central incisors.
   
   
3. Lower lateral incisors. The second pair of lower incisors, one on each side of the central incisors, generally appears about a month later.
   
   
4. First molars. The flat teeth in the back, two on top and two on bottom, tend to come after the lower lateral incisors.
   
   
5. Eyeteeth. The pointy teeth (canines) between the molars and incisors usually erupt next.
   
   
6. Second molars. The second set of flat teeth, two on top and two on bottom, usually come in last. They occur just behind the first set of molar and tend to appear at some point between the ages of 20 months and 30 months.

All 20 primary teeth are typically present by the time a child reaches 3 years of age. This set of teeth remains intact until the secondary (permanent) teeth are ready to erupt, which generally occurs somewhere around the age of 6 or 7 years.