Teething is the process during which an infant's teeth start to sequentially grow in. Teething can start as early as three months or as late, in some cases, as twelve months. It can take up to several years for all 20 deciduous (aka "baby" or "milk") teeth to emerge. The process of teething is sometimes referred to as "cutting teeth".

The infant teeth tend to emerge in pairs - first one upper incisor emerges then the other upper incisor emerges before the next set begin to emerge. The general pattern of emergence is:

1. Lower central incisors (2)
2. Upper central incisors (2)
3. Upper lateral incisors (2),
4. Lower lateral incisors (2)
5. First molars (4)
6. Canines (4)
7. Second molars (4)

Milk teeth tend to emerge sooner in females than in males. The exact patterns and initial starting times of teething appear to be hereditary. When and how teeth appear in an infant has no bearing on the healthiness or developmental ability of the child.

During teething, the new teeth are breaking through the surface of the gums. Signs of teething may include

• Poor mood
• Loss of appetite
• Chewing of objects
• Bruises/swelling in gums
• Excess salivation
• Slight fever

Infants chew on objects to aid in the teething process. This can be dangerous if the baby is allowed to chew on objects which are small enough to be swallowed or which could break while being chewed, creating a risk of choking. Teething rings and other toys are often designed with textures that will appeal to an infant during teething.

In cases where the infant is in obvious pain, some doctors recommend the use of anti-inflammatories or child-safe pain-relief treatments. Some infants gain relief from chewing on cold objects.

Dentists recommend brushing infants' teeth as soon as they appear. It is not necessary to wait for the teething process to complete. Dentists generally recommend against the use of toothpaste during teething.

See also dentition.