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How do germs make holes in the teeth?

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HealthWiki > Where There Is No Dentist > Chapter 4: School Activities for Learning about Teeth and Gums > How do germs make holes in the teeth?


Acid makes holes in the teeth. The acid is made when sweet foods mix with germs in your mouth.

It is not possible to prevent cavities or gum problems by trying to kill all of the germs in your mouth. There are too many — and some germs are good for you. The important thing is to keep the germs from getting together and making a film or coating on your teeth.

This film on the teeth is called plaque, but you do not need to use this word. Every morning we can all feel a ‘furry film’ on our teeth. This film must not be allowed to stay on the teeth! It will mix with sugar and make acid. Worse, if it stays in a group (or ‘colony’) for more than 24 hours, it will mix with saliva, harden, and make tartar.

The main reason for cleaning teeth is to break up these colonies so they cannot make acid. Also, if you forget to clean your teeth, tartar will form, and you will need a dental worker to scrape it off. This is why it is important to clean your teeth at least every 24 hours, so the tartar can never form on your teeth.


Here is a game called “Scatter!” that students can play outside. You need:

DENT Ch4 Page 50-1.jpeg
Children in Jocuixtita, Mexico, beginning a game of “Scatter!” The ‘decolonizer’ is the girl in the center with the broom.
  • Five ‘bases’ (a tree, rock, or the corner of a house can be a base) in a half circle, 12 meters apart. Each base must have a ‘monitor’ who stays at the base. Note: children who cannot run can be good monitors.
  • One person with a broom. This person is the ‘decolonizer

The Game:
20 students called ‘colonizers’ stand facing the decolonizer. When the decolonizer says “go!” they try to ‘form colonies’ around the bases before the decolonizer can touch them with the broom.

DENT Ch4 Page 51-1.jpeg
The 'decolonizer' (with broom) has lost the game. The children behind him have formed a 'colony'.
DENT Ch4 Page 51-2.jpeg
Here the decolonizer stops a boy from completing a chain.

The colonizers win if they make a colony. There are two kinds of colonies: (1) 15 people touching one monitor at a base, or (2) a chain of 12 people holding hands, touching two monitors.

Play two games: one with children trying to form the first kind of colony, one with the second kind. These photos are from the second game.

The decolonizer tries to stop the others by touching them with the broom. When the decolonizer touches a colonizer with the broom, the colonizer must leave the area for one minute.
(Give that child a task to do — run around the school-house or lie down and sit up 30 times.)

The decolonizer wins if no colonies form in 5 minutes.

a teacher speaking with students while he holds a large drawing of a circle.
How many germs do you see in this circle?
I don't see a thing!
That's right! They are much too small
to see!
To teach about things too small to see, look at the suggestion on page 11-29 of Helping Health Workers Learn.

After The Game:
Talk to the students about germs in their mouths and how small they are. Can anyone see germs? No, but they can feel them and taste them. Ask the group what their mouths feel like in the morning when they wake up. You may get these answers:

  • My teeth feel mossy.
  • My breath is bad.
  • I feel a coating on my teeth, but it goes away when I brush them.

Tell the students that this coating on the teeth is a ‘colony’ of germs. They are always trying to group together on the teeth or in spaces between the teeth — just as the ‘colonizers’ did in the game!

This page was updated:19 Feb 2018