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Human Body - Care of Teeth

Grade 4ICSE

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

🔑Concepts

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Human beings have two sets of teeth during their lifetime: Milk teeth (Temporary) and Permanent teeth. Milk teeth are 2020 in number, while a full set of permanent teeth contains 3232 teeth.

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The tooth consists of three main layers: Enamel (the hardest substance in the body containing Calcium CaCa and Phosphorus PP), Dentin (the layer below enamel), and Pulp (the soft innermost part containing nerves and blood vessels).

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There are four types of permanent teeth: Incisors for cutting, Canines for tearing, Premolars for cracking/crushing, and Molars for grinding food.

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Tooth decay occurs when bacteria in the mouth react with sugar to form acid. This acid dissolves the enamel, leading to cavities: Sugar+Bacteria→AcidSugar + Bacteria \rightarrow Acid.

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Proper care includes brushing twice a day, flossing, and consuming foods rich in Calcium (CaCa) and Vitamin CC to maintain gum and bone health.

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Plaque is a sticky, thin layer of bacteria that forms on teeth. If not removed, it can lead to tooth decay and gum diseases.

📐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

Dental Formula (Permanent)=21232123×2=32\text{Dental Formula (Permanent)} = \frac{2123}{2123} \times 2 = 32

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

💡Examples

Problem 1:

An adult has 44 quadrants in the mouth. If each quadrant has 33 molars, calculate the total number of molars in the mouth.

Solution:

1212 molars

Explanation:

Total molars = Number of quadrants×Molars per quadrant=4×3=12\text{Number of quadrants} \times \text{Molars per quadrant} = 4 \times 3 = 12.

Problem 2:

Why is Calcium (CaCa) important for our teeth?

Solution:

It strengthens the enamel.

Explanation:

The enamel is the outermost protective layer of the tooth and is primarily composed of minerals, mainly Calcium (CaCa), making it the hardest part of the human body.

Problem 3:

Identify the number of premolars in the set of milk teeth (temporary teeth).

Solution:

00

Explanation:

The milk teeth set consists of incisors, canines, and molars, but it does not contain any premolars. Premolars only appear in the permanent set.

Care of Teeth - Revision Notes & Key Formulas | ICSE Class 4 Science