Science 8th grade
UNIT 2: Food and digestion 2.5 Teeth
Science 8th grade
UNIT 2: Food and digestion 2.5 Teeth
The mouth is the first part of the alimentary canal. Inside your mouth there are four different kinds of teeth - incisors, canines, premolars and molars.
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The four kinds of human teeth.
Questions
$A + I$: 1) 'Canine' means 'dog tooth'. What do dogs use their canine teeth for?
2) Explain how the shape of incisors helps them to carry out their function.
3) Explain how the shape of molars helps them to carry out their function.
The structure of a tooth
The diagram shows what an incisor tooth looks like if it is cut in half. The diagram also shows the gum and jawbonc. Teeth are held in the jawbone by strong fibres.
Caring for your teeth
The enamel on your teeth is very strong. However, it can be dissolved by acids. If that happens, you may get a hole in your tooth. This can be painful when the hole reaches the pulp cavity, where there are nerve endings.
This means that drinking lots of acidic fizzy drinks (like cola or lemonade) can harm your teeth. Even if you don't eat or drink acidic things, you may still get acid in your mouth. This is because bacteria in your mouth break down food remains left on and between your teeth - especially sugary things. The bacteria make acid when they break down the food remains.
To avoid getting holes in your teeth:
• Don't drink fizzy drinks, or eat sugary food, all day long.
• Clean your teeth thoroughly after breakfast and before you go to bed.
• Use a toothpaste containing fluoride. Fluoride helps to strengthen the enamel on your teeth
Activity 2.5 (How do fizzy drinks affect teeth?)
SE: You'll only be able to do this activity if you can find two teeth. Your teacher may be able to provide these.
1) Tie a piece of strong cotton around each tooth, long enough to hang over the edge of a beaker.
Tie the other end around a small stone or weight.
2) Pour some fizzy drink (for example, cola) into one beaker. Pour the same depth of tap water into the other beaker.
3 Hang one tooth in the fizzy drink, and the other tooth in the water.
4 Observe the teeth at least once a week for several weeks. Write down your observations and conclusions.
