Tooth Decay Reading Comprehension Worksheet - Free Printable

Let's solve this Tooth Decay Reading Comprehension worksheet step by step using the diagram and the context of the passage.

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Step 1: Understand the Diagram

The diagram shows a cross-section of a tooth with labeled parts:
- Enamel: Outermost layer (white, hard)
- Dentine: Layer beneath enamel (orange)
- Pulp: Inner part containing nerves and blood vessels (pink)
- Nerves: Blue lines in the pulp
- Plaque: Yellow buildup on the tooth surface
- Tartar: Hardened plaque (green on the top of the tooth)
- Germ: Bacteria (purple dots)

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Step 2: Read the Passage and Fill in the Blanks

> __________ is formed by __________ in your mouth. Plaque is sticky and collects around your gum line and in grooves of your teeth. Untreated plaque forms __________. Plaque uses food we eat and drink, especially sugars, to form acids. These acids attack the outer layer of our teeth, the __________, eating it away. After a while, a small whole, called a __________, can form. When a cavity gets bad enough, it eats through to the __________, which is softer. Without treating the erosion, it will eat into the __________ where the __________ are, and this can be very painful.

Now, let’s fill in each blank based on the diagram and scientific knowledge:

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#### Blank 1: "__________ is formed by __________ in your mouth."

From the diagram, plaque is shown as a yellow substance on the tooth. It's formed by germs (bacteria), which are also shown in the diagram.

✔ So:
Plaque is formed by germs in your mouth.

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#### Blank 2: "Untreated plaque forms __________."

Plaque hardens into tartar, which is shown on the diagram as a green deposit above the gum line.

✔ So:
Untreated plaque forms tartar.

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#### Blank 3: "These acids attack the outer layer of our teeth, the __________..."

The outermost layer of the tooth is enamel, clearly labeled.

✔ So:
...the enamel, eating it away.

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#### Blank 4: "...a small whole, called a __________, can form."

When enamel is eaten away, a hole forms — this is called a cavity.

✔ So:
...called a cavity, can form.

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#### Blank 5: "When a cavity gets bad enough, it eats through to the __________, which is softer."

After enamel, the next layer is dentine, which is softer than enamel and shown in orange.

✔ So:
...to the dentine, which is softer.

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#### Blank 6: "Without treating the erosion, it will eat into the __________"

After dentine, the innermost part is the pulp, which contains nerves and blood vessels.

✔ So:
...eat into the pulp

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#### Blank 7: "...where the __________ are, and this can be very painful."

The nerves are located in the pulp. That’s why tooth decay reaching the pulp causes pain.

✔ So:
...where the nerves are...

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✔ Final Answer (Completed Passage):

> Plaque is formed by germs in your mouth. Plaque is sticky and collects around your gum line and in grooves of your teeth. Untreated plaque forms tartar. Plaque uses food we eat and drink, especially sugars, to form acids. These acids attack the outer layer of our teeth, the enamel, eating it away. After a while, a small whole, called a cavity, can form. When a cavity gets bad enough, it eats through to the dentine, which is softer. Without treating the erosion, it will eat into the pulp where the nerves are, and this can be very painful.

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📌 Summary of Answers:

1. Plaque
2. germs
3. tartar
4. enamel
5. cavity
6. dentine
7. pulp
8. nerves

This exercise teaches how tooth decay progresses from bacteria → plaque → tartar → acid → enamel erosion → cavity → dentine → pulp → nerve pain.

Let me know if you'd like a printable version or a teacher key!