为什么一天刷两次牙不一定是最好的？

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🤔️小作业：

1. According to the article, which statement best describes Dr Sharma's stance on brushing frequency?

A. Brushing twice daily is mandatory for preventing enamel erosion

B. Brushing once thoroughly can be more beneficial than brushing twice superficially

C. Brushing three times a day guarantees healthier gums

D. It is unnecessary to brush in the morning if brushing before bed is done correctly

无注释原文：

Why brushing teeth twice a day is not always best

From: BBC

We all think we know how to brush our teeth - a scrub morning and night, a rinse with water and maybe a minty mouthwash for good measure.

But according to dental experts, even the most diligent brushers might be making a few mistakes that could be undoing their good work.

Dr Praveen Sharma, from the school of dentistry at the University of Birmingham, says that half of adults in the UK will have gum disease at some point and an early sign is bleeding gums.

"If your gums are bleeding or swollen it's a sign you need to brush better," he says.

As well as regular dentist visits, here are things he and BBC's What's Up Docs podcast hosts Dr Xand and Dr Chris van Tulleken, say many of us are currently getting wrong which if we change could improve the health of our teeth.

1. Brushing once well is better than twice quickly

It's one of the great dental commandments - brushing twice a day - and that's what the NHS recommends.

But Dr Sharma says the real key is quality, not quantity.

"If you can find time, then yes, brush properly twice a day," he says. "But it's better to do it once a day well and once quickly for two minutes.

If you only have time to brush and floss properly once a day then he recommends it be in the evening.

Of course, no one likes flossing, but Dr Sharma says using interdental brushes can make it easier and less painful.

When it comes to the method, each tooth has an outer, biting and inner surface and all three need to be brushed.

Dr Sharma advises small circular motions over each surface without applying too much pressure. He also says to pay particular attention to the junction between the tooth and the gum as that's where gum disease can occur.

Dr Xand says it's important to "focus on the sensation of the bristles" and approach tooth brushing mindfully, not scrolling on your phone at the same time.

2. Brush before breakfast, not after

Many people brush their teeth right after eating, but that might not be doing your enamel any favours.

"Ideally, brush before breakfast," Dr Sharma says. "You don't want to do it after something acidic.

"If you do brush after, then you need to leave some space between eating and brushing."

That's because acids from foods and drinks, especially fruit juice or coffee, can soften tooth enamel and brushing too soon afterwards can wear it away.

Dr Chris suggests rinsing your mouth with water after eating to get rid of some acid and then waiting at least 30 minutes if you are brushing after breakfast.

3. Don't rinse after brushing

If you've been spitting, rinsing and gargling after every brush, you might want to rethink that last step.

"You spit but don't rinse with water," Dr Sharma advises. Rinsing your mouth washes away the concentrated fluoride in the remaining toothpaste.

That means simply spitting out the excess toothpaste and leaving the thin layer of fluoride behind to continue protecting your teeth.

If you want to rinse your mouth after brushing, use a mouthwash.

- ◆ -

注：完整题目见本文开头；中文文本为BBC官方译文，仅供参考

含注释全文：

Why brushing teeth twice a day is not always best

From: BBC

We all think we know how to brush our teeth - a scrub morning and night, a rinse with water and maybe a minty mouthwash for good measure.

我们都以为自己知道如何刷牙──早晚各刷一次，用水漱口，再加上清新的薄荷漱口水，似乎万无一失。

scrub /skrʌb/ 可以作名词也可以作动词，1）表示“（尤指用硬刷、肥皂和水）擦洗，刷洗”，英文解释为“to rub something hard in order to clean it, especially using a stiff brush, soap, and water”举个🌰：She scrubbed (at) the mark on the wall for a long time, but it wouldn't come off. 她花了很长时间擦洗墙上的印迹，但仍然没有擦掉。

2）表示“取消（原计划）”，英文解释为“to decide not to do something you had planned to do”举个🌰：We had to scrub our plans when I lost my job. 我失业了，我们不得不取消计划。

rinse /rɪns/ 作动词，表示“（用清水）冲洗，涮洗，漂洗”，英文解释为“to use water to clean the soap or dirt from something”举个🌰：First apply shampoo to hair and then rinse thoroughly. 先把洗发剂涂抹在头发上，然后冲洗干净。

📍rinse, repeat 指的就是某个过程，某些事情需要不断重复地做（used to indicate the continual repetition of an action or sequence of events, typically in a way regarded as tiresomely predictable），源自洗发水上的使用说明，Lather, rinse, repeat（挤出泡沫、冲水、重复）。

作名词，表示“冲洗；涮洗；漂洗”，英文解释为“the process of using water to get rid of soap or dirt”举个🌰：He gave the soapy dishes a rinse. 他把满是肥皂沫的盘子冲洗了一下。

minty /ˈmɪn.ti/ 表示“有薄荷香的；有薄荷味的”，英文解释为“tasting or smelling of mint (= a herb with a strong, fresh flavour)”举个🌰：I loved the fresh minty taste. 我喜欢清新的薄荷味。

But according to dental experts, even the most diligent brushers might be making a few mistakes that could be undoing their good work.

但根据牙科专家的说法，即使是最勤奋刷牙的人，也可能犯下一些错误，抵消了他们的努力成果。

1）表示“认真刻苦的，勤奋的，勤劳的”，英文解释为“careful and using a lot of effort”如：a diligent student 用功的学生。

2）表示“细致的，潜心的”，英文解释为“done in a careful and detailed way”举个🌰：The discovery was made after years of diligent research. 这一发现是数年潜心研究的成果。

Dr Praveen Sharma, from the school of dentistry at the University of Birmingham, says that half of adults in the UK will have gum disease at some point and an early sign is bleeding gums.

英国伯明翰大学牙医学院的普拉文·沙尔玛博士（Dr Praveen Sharma）指出，英国有一半的成年人一生中某个时期会患上牙龈疾病，而早期征兆之一就是牙龈出血。

gum /ɡʌm/ 1）表示“齿龈，牙龈，牙床”，英文解释为“either of the two areas of firm pink flesh inside the mouth that cover the bones into which the teeth are fixed”如：sore gums 牙龈疼痛。

2）表示“口香糖（同 chewing gum）；泡泡糖（同 bubble gum）”，英文解释为“ chewing gum or bubble gum (= a soft sweet that you crush with your teeth but do not swallow)”

"If your gums are bleeding or swollen it's a sign you need to brush better," he says.

“如果你的牙龈在出血或肿胀，那代表你需要更好地刷牙。”他说。

swollen /ˈswəʊlən/ 表示“肿胀的；肿起来的”，英文解释为“(of a part of the body) larger than normal, especially as a result of a disease or an injury”举个🌰：Her eyes were red and swollen from crying. 她哭得两眼又红又肿。

As well as regular dentist visits, here are things he and BBC's What's Up Docs podcast hosts Dr Xand and Dr Chris van Tulleken, say many of us are currently getting wrong which if we change could improve the health of our teeth.

除了定期看牙医外，他与BBC播客节目的主持人──双胞胎医生山德与克里斯·范·图勒肯（Dr Xand 和 Dr Chris van Tulleken）──总结了我们常犯的错误。若能改正，将有助于改善牙齿健康。

1. Brushing once well is better than twice quickly 一次认真刷牙胜过两次草率刷牙

It's one of the great dental commandments - brushing twice a day - and that's what the NHS recommends.

几乎所有牙医都会叮嘱——每天刷两次牙——这也是英国国民保健署（NHS）的建议。

commandment /kəˈmɑːnd.mənt/ 表示“命令，指示；戒条”，英文解释为“an order”

But Dr Sharma says the real key is quality, not quantity.

但沙尔玛博士说，关键在于品质而非次数。

quantity /ˈkwɒn.tə.ti/ 表示“（尤指可测量或确定的）量，数量，分量”，英文解释为“the amount or number of something, especially that can be measured”举个🌰：We consumed vast quantities of food and drink that night. 那天晚上我们大吃大喝了一通。

"If you can find time, then yes, brush properly twice a day," he says. "But it's better to do it once a day well and once quickly for two minutes.

“如果你能抽出时间，那当然最好每天早晚都好好刷牙；但若只能选一次，那就保证有一次刷得彻底，另一次快速刷两分钟即可。”

If you only have time to brush and floss properly once a day then he recommends it be in the evening.

若只能在一天中挑一次时间彻底刷牙和使用牙线，他建议最好安排在晚上。

floss /flɒs/ 表示“用牙线清洁（牙缝）”，英文解释为“to clean between your teeth using dental floss”举个🌰：It's important to floss every day. 每天用牙线清洁牙缝很重要。

Of course, no one likes flossing, but Dr Sharma says using interdental brushes can make it easier and less painful.

当然，多数人不喜欢用牙线，但他建议可以改用牙缝刷，较容易使用也不那么疼痛。

interdental /ˌɪn.təˈden.təl/ 表示“牙齿间的；在牙齿间使用的”，英文解释为“between the teeth or for use between the teeth”如：interdental spaces 牙间隙。

When it comes to the method, each tooth has an outer, biting and inner surface and all three need to be brushed.

在方法上，每颗牙都有外侧、咬合面与内侧三个面，这三个面都需要刷到。

Dr Sharma advises small circular motions over each surface without applying too much pressure. He also says to pay particular attention to the junction between the tooth and the gum as that's where gum disease can occur.

他建议使用小圆圈的刷牙动作，不要太用力，并特别注意牙龈与牙齿交界处，那是牙周病最容易发生的地方。

circular /ˈsɜːkjʊlə/ 1）作形容词，表示“圆形的”，英文解释为“Something that is circular is shaped like a circle.”如：a circular hole 圆洞。

2）表示“（旅行或路线）环行的”，英文解释为“A circular journey or route is one in which you go to a place and return by a different route.”举个🌰：Both sides of the river can be explored on this circular walk. 沿着这条环形步行道走，河的两边就都可以看得到了。

3）表示“循环论证的；迂回而无效的”，英文解释为“A circular argument is one that keeps returning to the same points and is not effective.”

4）作名词，表示“（同时发给很多人的）通知，通报，传单”，英文解释为“A circular is an official letter or advertisement that is sent to a large number of people at the same time.”举个🌰：The proposal has been widely publicized in press information circulars sent to 2,345 newspapers. 通过向2345份报纸发送新闻通告，这项提议得到了广泛地宣传。

junction /ˈdʒʌŋkʃən/ 表示“联结点；枢纽；（公路的）交叉口；（铁路）联轨站”，英文解释为“a place where things, especially roads or railways, come together”举个🌰：You should slow down as you approach the junction. 接近交叉口时你应该减速。

Dr Xand says it's important to "focus on the sensation of the bristles" and approach tooth brushing mindfully, not scrolling on your phone at the same time.

山德医生补充说，刷牙时要“专注于牙刷刷毛接触的感觉”，不要边刷牙边滑手机，应该有意识地进行。

sensation /senˈseɪ.ʃən/ 1）表示“轰动；哗然；引起轰动的人（或事物）”，英文解释为“very great surprise, excitement, or interest among a lot of people; the person or the thing that causes this surprise”举个🌰：The band became a sensation overnight. 一夜之间，这支乐队名声大振。

📍此前，戳爷Troye Sivan被传已分手数月？文中出现过，pop sensation可以理解为“流行巨星”，“流行天王”。还有，63岁中国爷爷成油管网红文中标题就是Master carpenter's ancient Chinese skills are a YouTube sensation.

2）作可数名词，还可以表示“感觉；知觉”，英文解释为“a feeling that you get when sth affects your body”如：a tingling/burning sensation 刺痛/烧灼的感觉。

3）作不可数名词，可以表示“感觉能力；知觉能力”，英文解释为“the ability to feel through your sense of touch”举个🌰：She seemed to have lost all sensation in her arms. 她的两条胳膊好像完全失去知觉了。

🎬电影《困在爱中》（Stuck in Love）中的台词提到：I was overcome by the oddest sensation. 我像是被一种怪异的冲动（感觉）驱使着。

📍词根“-sens-”来自拉丁语“sensare”，表示“感觉”。近义词：phenomenon（现象），同根词：sensitive（敏感的），常用短语：cause a sensation（引起轰动）

bristle /ˈbrɪs.əl/ 表示“刷子毛”，英文解释为“The bristles of a brush are the stiff hairs or pieces of plastic that are connected to it.”举个🌰：My toothbrush has blue and white plastic bristles. 我的牙刷上有蓝白塑料刷毛。

作名词，scroll /skrəʊl/ 表示“长卷纸，卷轴”，英文解释为“a long roll of paper or similar material with usually official writing on it”举个🌰：The ancient Egyptians stored information on scrolls. 古埃及人把信息记载在卷轴上。

作动词，表示“滚动；滚屏”，英文解释为“to move text or other information on a computer screen in order to see a different part of it”举个🌰：Scroll to the end of the document. 滚动至文件的最后。

🎬电影《兔子洞》（Rabbit Hole）中的台词提到：Scroll down with your finger. 用手指向下滑动。

2. Brush before breakfast, not after 早餐前刷牙，而不是之后

Many people brush their teeth right after eating, but that might not be doing your enamel any favours.

许多人习惯在吃完早餐后刷牙，但这样可能会损伤珐瑯质。

enamel /ɪˈnæm.əl/ 表示“（牙齿的）珐琅质，釉质”，英文解释为“the hard, white, shiny substance that forms the covering of a tooth”

"Ideally, brush before breakfast," Dr Sharma says. "You don't want to do it after something acidic.

“理想的情况是早餐前刷牙，”沙尔玛博士说，“尤其不要在吃过酸性食物后立刻刷。”

acidic /əˈsɪd.ɪk/ 表示“酸性的”，英文解释为“containing acid”如：acidic soil 酸性土壤；或表示“很酸的”，英文解释为“very sour”如：a slightly acidic taste 微酸的味道。

"If you do brush after, then you need to leave some space between eating and brushing."

“如果你一定要在饭后刷牙，你应该在吃完东西与刷牙之间间隔一段时间。”

That's because acids from foods and drinks, especially fruit juice or coffee, can soften tooth enamel and brushing too soon afterwards can wear it away.

这是因为食物和饮品中的酸性成分，特别是果汁与咖啡，会软化牙齿表面的珐瑯质，而太快刷牙会把它磨掉。

Dr Chris suggests rinsing your mouth with water after eating to get rid of some acid and then waiting at least 30 minutes if you are brushing after breakfast.

克里斯医生建议，可以先用清水漱口去除部分酸性，再等至少30分钟再刷牙。

3. Don't rinse after brushing 刷完牙不要漱口

If you've been spitting, rinsing and gargling after every brush, you might want to rethink that last step.

如果你每次刷完牙都会吐掉牙膏、用水漱口、再喉咙一漱——可能该重新思考这个步骤。

gargle /ˈɡɑː.ɡəl/ 表示“（尤指为清洁口腔或止痛）漱口，漱喉，含漱”，英文解释为“to move a liquid around in your throat without swallowing, especially to clean it or stop it feeling painful”

"You spit but don't rinse with water," Dr Sharma advises. Rinsing your mouth washes away the concentrated fluoride in the remaining toothpaste.

“你应该吐掉，但不要用水漱口。”沙尔玛博士说。因为漱口会冲掉牙膏中浓缩的氟化物。

fluoride /ˈflɔː.raɪd/ 表示“氟化物”，英文解释为“a chemical substance sometimes added to water or toothpaste (= substance for cleaning teeth) in order to help keep teeth healthy”

That means simply spitting out the excess toothpaste and leaving the thin layer of fluoride behind to continue protecting your teeth.

这意味着只需吐掉多余的牙膏，留下薄薄一层氟化物继续保护牙齿即可。

If you want to rinse your mouth after brushing, use a mouthwash.

如果真的想漱口，可以改用漱口水。

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