Two sets of teeth
You get two sets of teeth in your life. The first set is your baby teeth, also called primary teeth. There are 20 of them, and they start coming in when babies are about 6 months old.
Under your baby teeth, your grown-up teeth are already growing inside your jaw, waiting for their turn.
Grown-ups have 32 teeth. That includes four wisdom teeth at the very back, which usually come in between about ages 17 and 21. Some people never get them at all.
Losing baby teeth
Most kids lose their first baby tooth around age 6. Often the bottom front teeth go first.
Here's how it works: the grown-up tooth underneath pushes up, and the baby tooth's root slowly dissolves. The tooth gets wiggly and finally falls out. It usually doesn't hurt much.
Losing teeth happens bit by bit over several years. Most kids have lost all their baby teeth by about age 12 or 13.
Baby teeth matter even though they fall out. They help you chew and talk, and they save space for your grown-up teeth.
What's inside a tooth
The white outside of your tooth is enamel. It's the hardest stuff in your whole body, even harder than bone!
Under the enamel is dentin (DEN-tin). It's a bit softer and a little yellow.
In the middle is the pulp. It's soft and holds nerves and blood vessels. That's why a tooth can feel cold ice cream, or hurt when something is wrong.
The root is the part hidden under your gums. It holds your tooth tight in your jawbone, the way roots hold a tree in the ground.
Four kinds of teeth
Incisors (in-SIZE-ers) are the flat front teeth. They cut and bite, like when you bite into an apple.
Canines (KAY-nines) are the pointy teeth next to them. They grip and tear food. They're named after dogs, who have big pointy ones.
Premolars and molars are the wide, bumpy teeth in the back. They crush and grind food into mush. Baby teeth don't have premolars, only molars.
Try it: run your tongue over your teeth from front to back. Can you feel the flat ones, the pointy ones and the bumpy ones?
Brushing and keeping teeth strong
Germs called bacteria live in your mouth. When they eat bits of sugary food, they make acid that can wear tiny holes in your enamel. These holes are called cavities.
Brushing sweeps away the sticky stuff called plaque (PLAK). Brush twice a day, morning and night, for two minutes each time. Humming a song in your head helps you brush long enough.
Use toothpaste with fluoride (FLOR-ide), which helps make enamel stronger. Use just a small dab, the amount a grown-up shows you.
Floss once a day to clean between your teeth, where a brush can't reach. And visit the dentist for checkups.