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托福听力练习-科学美国人60秒:氟对抗蛀牙

2017-03-09 15:02:00来源：科学美国人60秒

点击查看>>科学美国人60秒音频：氟对抗蛀牙

　　科学美国人60秒中英文翻译：氟对抗蛀牙

　　科学美国人60秒英文文本

　　Fluoride helps fight cavities. That's why it's in our drinking water and toothpaste. But how this mineral works its dental magic is still somewhat mysterious. Now, researchers offer an incisive solution. They find that fluoride treatment can loosen bacteria's grip on tooth enamel. The study is in the journal Langmuir.

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　　Scientists used to think that fluoride could harden tooth enamel, helping it retain the minerals that protect teeth from the acid produced by our oral flora. But recent work has shown that fluoride doesn't really penetrate past the tooth's thinnest outer layer, suggesting that something other than hardening is going on.

　　To drill deeper into this toothsome mystery, researchers whipped up a set of artificial choppers, made of the same stuff as teeth. And they used atomic force microscopy to take a closer look at how bacteria interact with this dental material. They found that three different strains of cavity-causing bugs cling less tightly to enamel that's been rinsed with fluoride.

　　The bacteria carry a net negative charge on their surfaces. So the negatively charged fluoride ions in the treated enamel may be literally repulsive to the bacteria. Which causes them to bite the dust.

　　中文翻译请点击下一页

本文关键字: 托福听力练习 科学美国人60秒

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