My teeth
Milk teeth and adult teeth, what different teeth do, and why sugar and germs are bad news for teeth. With an eggshell-in-vinegar experiment.
Read
A baby's first teeth start to come through when the baby is about six months old. They are called milk teeth or baby teeth.[4][5]
Children have 20 milk teeth. When you are about 6, they start to wobble and fall out one by one, and bigger adult teeth grow in their place. Grown-ups can have 32 teeth.[5][4]
Teeth have different jobs. Your flat front teeth cut food, your pointy teeth tear it, and your big back teeth crush and grind it.[5][4]
The outside of a tooth is covered in enamel. It is the hardest stuff in your whole body![5][4]
Tiny germs called bacteria live on your teeth. When you eat sugar, they make acid, and acid can slowly make holes in your teeth.[3]
So brush your teeth twice a day for about 2 minutes with fluoride toothpaste. Then spit, don't rinse, so the toothpaste keeps working.[1]
Try it: The egg in vinegar
You need
- 2 eggs (hard-boiled is less messy)
- 2 clear cups or jars
- Water
- White vinegar
- A magnifying glass (optional)
Safety
An adult pours the vinegar. Vinegar stings if it gets in your eyes, so don't rub your eyes and wash your hands afterwards. Wash hands after touching eggs. Do not eat the eggs. Check for egg allergies first.
What to do
- Look at the eggs. Tap them gently. Is the shell hard? Our eggshell is going to pretend to be the outside of a tooth.
- Put one egg in a cup and cover it with water.
- The teacher puts the other egg in a cup and covers it with vinegar. Vinegar is an acid.
- Look closely at both cups. Which egg gets tiny bubbles on it?
- Leave the cups until the next day. Then gently touch both shells. Which one has gone soft or thin?
What happens, and why?
An eggshell is made of a hard material called calcium carbonate, a bit like the hard outside of a tooth. Vinegar is an acid. The acid reacts with the shell and makes bubbles of a gas called carbon dioxide, and the shell gets thinner and softer. The acid that germs make from sugar attacks the enamel on our teeth in a similar way, only much more slowly.[10][11][3]
Play: Happy teeth?
Read each card. Does it help your teeth or harm your teeth? Pick the right box.
Your best score is kept only on this device. Nothing is sent anywhere.
Quiz
Other ages: Ages 10–11 · Ages 15–16