字幕列表 影片播放 列印英文字幕 Smart Learning for All Topic: Tooth decay. What causes cavities? A black sketch pen. No. Our mouth contains billions of bacteria which live on our teeth, tongue, etc. Most of these bacteria are usually harmless. Just like me, right? Now listen. A tooth consists of enamel, dentin and pulp. Enamel is mostly made up of minerals. Dentin is a layer underlying the enamel. Whereas, pulp has blood vessels and nerves. Now, when we eat foods containing sugars, some of these bacteria feed on the sugars producing acid. This acid starts to dissolve the minerals of the tooth enamel, causing tooth decay. Usually, our saliva restores these minerals, thus preventing further decay. But if we continuously eat sugary foods, then our saliva cannot keep up. Causing the bacteria to pass into the dentin and then eventually into the pulp, thus creating cavities. For more educational videos please visit http://www.SmartLearningforAll.com Also, don't forget to subscribe to our YouTube channel.