trinhhaidang2k1 3/14/2025 8:13:36 AM

(I) The cause of tooth decay is acid, which is produced by bacteria in the mouth. (II) The rate at which bacteria in the mouth produce acid depends on the amount of plaque on the teeth, the composition of the microbial flora, and whether the bacteria of the plaque have been "primed" by frequent exposure to sugar. (III) To keep your teeth healthy, a regular dental hygiene program should be followed. (IV)

Removing plaque with a toothbrush and dental floss temporarily reduces the numbers of harmful bacteria in the mouth, thereby lowering the risk of tooth decay. This practice also makes the surfaces of the teeth more accessible, which enables saliva to neutralize acid and remineralize lesions. If fluoride is present in drinking water when teeth are forming, some fluoride is incorporated into the enamel of the teeth, making them more resistant to attack by acid. Fluoride toothpaste seems to act in another way, by promoting the remineralization of early carious lesions.

In addition to a regular dental hygiene program, a good way to keep your teeth healthy is to reduce your intake of sweet food. The least cavity-causing way to eat sweets is to have them with meals and not between. The number of times you eat sweets rather than the total amount determines how much harmful acid the bacteria in your saliva produce. But the amount of sweets influences the quality of your saliva. Avoid, if you can, sticky sweets that stay in your mouth a long time. Also try to brush and floss your teeth after eating sugary foods. Even rinsing your mouth with water is effective.

Whenever possible, opt for foods with fiber, such as raw carrot sticks, apples, celery sticks, etc., that naturally scrape off plaque, acting as a toothbrush. Following these guidelines when consuming sweets and maintaining a thorough oral care routine can significantly reduce the risk of cavities and improve overall dental health.

(Adapted from https://www.verywellhealth.com/tooth-erosion)

Question 21. Where in paragraph 1 does the following sentence best fit?

"The acid removes minerals from tooth enamel, allowing tooth decay to begin."

A. (II)        B. (IV)        C. (III)        D. (I)

Question 22. The word them in paragraph 2 refers to______

        A. lesions        B. bacteria        C. teeth        D. drinking water

Question 23. Which of the following best paraphrases the underlined sentence in paragraph 2?

A. Toothbrushes and dental floss remove bacteria and plaque from the mouth, but in fact they do not reduce the risk of tooth decay.

B. The risk of tooth decay temporarily increases when plaque is not removed by dental floss and a toothbrush.

C. Cleaning teeth using a toothbrush and dental floss can help remove plaque and temporarily decrease the bacteria that cause tooth decay.

D. Using dental floss and a toothbrush permanently eliminates all harmful bacteria present in the mouth and prevents tooth from decaying.

Question 24. The word sticky in paragraph 3 is OPPOSITE in meaning to_____

A. loose        B. soft        C. dry        D. adhesive

Question 25. We can infer from the passage that one benefit of fluoride to healthy teeth is_______

A. It makes teeth whiter

B. It stimulates saliva production

C. It strengthens tooth enamel

D. It is a replacement for brushing

Question 26. Which of the following best summarises paragraph 3?

A. Eating more sweets with meals, avoiding sticky ones, and brushing can prevent cavities effectively.

B. Reducing sweets, avoiding sticky ones, and maintaining oral hygiene can lower tooth decay risk.

C. A balanced diet and fiber-rich foods can remove plaque and prevent decay better than oral hygiene.

D. Fiber-rich foods, increased sweets, and rinsing can help maintain oral health and prevent cavities.

Question 27. According to the passage, which of the following is NOT mentioned as a factor affecting the production of acid by bacteria in the mouth?

A. The frequency of sugar consumption

B. The amount of plaque on the teeth

C. The composition of the microbial flora

D. The amount of water consumed daily

Question 28. The author states that the amount of acid produced by the bacteria in your saliva increases________.

A. with the total amount of sweets you eat

B. with the number of times you consume sweets

C. if you consume sticky sweets on a regular basis

D. if you eat a lot of sweets with your meals

Question 29. The phrase scrape off can best be replaced by_______

        A. take on        B. check in        C. wipe off        D. build up

Question 30. Which of the following best summarizes the passage?

A. Fluoride use is a sufficient way for people to prevent tooth from decaying, without the need for brushing

B. The key to healthy teeth is avoiding all sweets and only using fluoride toothpaste to prevent decay.

C. Eating sweets with meals and brushing immediately after helps reduce the risk of cavities without fluoride.

D. Regular dental hygiene and a diet low in sugar help prevent tooth decay and promote healthy teeth.

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