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Teeth and the World of Microbes - Dental Care and Hygiene

Grade 4CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Human beings have two sets of teeth: Milk teeth (temporary set of 2020 teeth) and Permanent teeth (adult set of 3232 teeth).

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A tooth consists of three main layers: The outermost hard layer called Enamel, the middle layer called Dentin, and the innermost soft part called Pulp which contains nerves and blood vessels.

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There are four types of teeth based on their functions: Incisors for cutting (88), Canines for tearing (44), Premolars for cracking (88), and Molars for grinding (1212).

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Tooth decay occurs when bacteria react with sugar to produce acid: Sugar+Bacteria→Acid\text{Sugar} + \text{Bacteria} \rightarrow \text{Acid}. This acid dissolves the enamel, leading to cavities.

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Microbes are tiny organisms that can only be seen through a microscope. They include Bacteria, Viruses, Fungi, and Protozoa.

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Helpful microbes include LactobacillusLactobacillus, which converts milk into curd, and YeastYeast, which is used in baking bread.

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Harmful microbes, also known as germs, cause diseases like typhoid (bacteria), common cold (virus), and malaria (protozoa).

📐Formulae

Total Permanent Teeth=8 Incisors+4 Canines+8 Premolars+12 Molars=32\text{Total Permanent Teeth} = 8 \text{ Incisors} + 4 \text{ Canines} + 8 \text{ Premolars} + 12 \text{ Molars} = 32

Milk Teeth Count=20\text{Milk Teeth Count} = 20

Sugar+Bacteria→reactionAcid→Cavity (Tooth Decay)\text{Sugar} + \text{Bacteria} \xrightarrow{\text{reaction}} \text{Acid} \rightarrow \text{Cavity (Tooth Decay)}

💡Examples

Problem 1:

Calculate the total number of grinding teeth (Molars and Premolars) in a complete set of permanent teeth.

Solution:

2020 teeth

Explanation:

In a permanent set, there are 88 premolars and 1212 molars. Therefore, 8+12=208 + 12 = 20 teeth are used for grinding and crushing food.

Problem 2:

Identify the microbe responsible for the fermentation of dough in the kitchen.

Solution:

YeastYeast (a type of fungus)

Explanation:

YeastYeast is a fungus that reacts with sugars in the dough to produce CO2CO_2 gas, which makes the bread or cake soft and fluffy.

Problem 3:

Why do dentists recommend brushing twice a day in the context of pH levels?

Solution:

To prevent acid formation.

Explanation:

Brushing removes food particles and prevents Bacteria+Sugar→Acid\text{Bacteria} + \text{Sugar} \rightarrow \text{Acid} reaction, maintaining a healthy environment for the Enamel.