Name: 為什麼要在水中添加氟化物？| 為什麼要在水中添加氟化物？ (Why is fluoride added to water? | #aumsum)
Uploaded: 2021-01-14T08:11:00.000Z
Duration: 1 min 4 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

基礎被動語態

When fluoride is added to public water supplies.

At an average concentration of about 1 part per million or slightly below, it prevents tooth decay.

Enamel is the hard outer covering of our tooth.

It is primarily made up of hydroxyapatite.

Hydroxyapatite is a compound of calcium, phosphorus and hydroxide.

Now, when bacteria in our mouth feed on food particles, they produce acid.

This acid dissolves the hydroxyapatite leaving behind a residue of calcium and phosphate ions.

Now, when we drink water containing fluoride.

The fluoride binds with calcium and phosphate ions forming fluorapatite.

As fluorapatite is less susceptible to acid attacks, it helps to stop the tooth decay process.

For more educational videos please visit http://www.SmartLearningforAll.com

Also, don't forget to subscribe to our YouTube channel.