英語聽力文摘 長蛀牙,怎么辦？
Don: Sorry, I'm late. I was brushing my teeth.
Yaël: Brushing your teeth! Right before A Moment of Science? Why?
D: I'm trying to get rid of a cavity.
Y: Get rid of a cavity? Are you stuck with a cavity once you have it?
D: It depends on how deep it is. Acid from bacteria in your mouth can cause your tooth to decay. First, the acid eats away the very hard outer layer of your tooth, called the enamel. Inside the enamel is the dentin. It’s spongy and has nerve endings, so your tooth might be sensitive to sweets or cold if the decay reaches there.
But the cavity doesn’t really start to hurt until it gets through the dentin to the soft pulp. That’s when you get a toothache.
Y: Ow!
D: Dentists sometimes will fill a cavity by putting in a filling while the decay is still in the enamel. But decay is reversible until it reaches the dentin. If it’s properly treated, the decay will stop, and the enamel will harden, although the tooth will never be perfect again.
Y: So, that's why you're brushing. Can you do anything else to help get rid of a cavity?
D: Dentists can help by giving you a fluoride treatment, but you have to brush and floss regularly. You might have to give up soda and sweets. So it’s not easy–and dentists know that. That’s why they sometimes fill a cavity in its early stages, before it starts to hurt.
Y: So, you’re not stuck with tooth decay once it happens.
D: Nope. But it’s better not to let it happen in the first place.
擺脫蛀牙的煩惱
D: 對不起，我遲到了。我剛剛刷牙去了!
Y: 刷牙!就在節(jié)目開始前!為什么啊?
D: 防止蛀牙啊!
Y: 防止蛀牙?你長過蛀牙嗎?
D: 這就得看牙被蛀得有多深了?？谇恢械募毦鷷a生一些腐蝕牙齒的酸性物質。酸性物質會先腐蝕掉牙冠表層的琺瑯質(也就是我們所熟知的釉質)?，m瑯質所包覆的便是牙本質。牙本質不如琺瑯質堅硬，其中還含有很多的神經末梢。因而，如果牙本質也受到了腐蝕，牙齒對甜食或是過冷的東西就會很敏感。
但是，要等到酸性物質通過牙本質，開始腐蝕牙髓了才會對牙齒造成本質的傷害。這個時候牙齒也就開始疼起來了。
Y: 肯定會很疼!
D: 當琺瑯質遭到腐蝕時，醫(yī)生有的時候會采取補牙的方式進行治療?？墒?，在牙本質遭到腐蝕之前，腐蝕隨時都會發(fā)生。如果治療得當，腐蝕將會停止，琺瑯質也會重新變硬，美中不足的是，牙齒不會像受腐蝕前那么完美了。
Y: 這就是你剛剛刷牙的原因!你還有其他防蛀牙的辦法嗎?
D: 醫(yī)生還可以為你做氟化物治療(在蛀牙部位涂上高濃度的氟化物，令初期蛀壞的部分還原)，但是，你必須定期洗牙，還要經常使用牙線清潔牙齒。另外，什么汽水啊，甜食啊，都必須戒掉。所以說，做這個治療并不容易——當然，醫(yī)生們也是很清楚的。這也是為什么醫(yī)生會在蛀牙初期的時候為病人補牙，防止酸性物質的繼續(xù)腐蝕。
Y: 這么說，你從來都沒有長過蛀牙。
D: 當然。但是，“防患于未然”總是好的啊!
