Deciduous teeth is the official term for baby teeth, milk teeth, or primary teeth. Deciduous teeth start developing during the embryonic stage and then commonly begin to come in about 6 months after birth.

There are typically 20 primary teeth — 10 upper and 10 lower. Commonly, most of them erupt by the time the child is about 2½ years old.

Typically, your baby’s teeth will start coming in when they’re about 6 months old. The first tooth to come in is usually the central incisor — middle, front tooth — on the lower jaw. The second tooth to come is usually right next to the first: the second central incisor on the lower jaw.

The next four teeth to come in are usually the four upper incisors. They usually start erupting about two months after the same tooth on the lower jaw comes in.

The second molars are usually the last of the 20 deciduous teeth, coming in when your baby is about 2½ years old.

Everyone is different: Some get their baby teeth earlier, some get them later. If you have questions or concerns about your child’s primary teeth, ask your dentist.

The American Academy of Pediatric Dentistry suggests that your baby’s first dental visit should be before they reach age 1, within 6 months after their first tooth appears.

Your child’s 20 baby teeth will be replaced with 32 permanent, or adult, teeth.

You can expect your child to begin losing their deciduous teeth around the age of 6. The first ones to go are commonly the first that came in: the central incisors.

Your child will usually lose the last deciduous tooth, typically the cuspid or second molar, around the age of 12.

The differences between primary teeth and adult teeth include:

  • Enamel. Enamel is the hard outer surface that protects your teeth from decay. It’s usually thinner on primary teeth.
  • Color. Deciduous teeth often look whiter. This can be attributed to thinner enamel.
  • Size. Primary teeth are typically smaller than permanent adult teeth.
  • Shape. Front permanent teeth often come in with bumps that tend to wear off over time.
  • Roots. Roots of baby teeth are shorter and thinner because they’re designed to fall out.

Deciduous teeth — also known as baby teeth, primary teeth, or milk teeth — are your first teeth. They start developing during the embryonic stage and start to erupt through the gums about 6 months after birth. All 20 of them are typically in by age 2½.

The deciduous teeth start falling out around age 6 to be replaced by 32 permanent adult teeth.