Brushing your teeth effectively lowers your chances of getting a host of chronic diseases, as well as keeping your teeth and gums healthy. But the majority of us are doing it wrong.

有效刷牙可以大大降低患上多种慢性疾病的风险，同时也能保持牙齿和牙龈的健康。但我们大多数人刷牙的方式都是错误的。

In Sweden, one study found as few as one in 10 people practice the best brushing technique. The British health insurer Bupa found that almost half of respondents did not know how to brush their teeth properly in a survey of 2,000 people in the UK.

瑞典的一项研究发现，只有十分之一的人掌握了最佳的刷牙技巧。英国健康保险公司Bupa在一项涵盖了2000名英国人的调查中发现，近半数受访者不知道如何正确刷牙。

So what exactly are most of us getting wrong, and how can we change our routine to make sure we brush our teeth effectively? Here's how to properly brush your teeth, according to experts.

那么我们大多数人到底错在哪里？我们应该如何改变日常习惯以确保我们有效地刷牙呢？来看看专家建议的正确刷牙方法。

"Lots of patients understand that what they need to do is remove food remnants," says Josefine Hirschfeld, associate professor and specialist in restorative dentistry at the University of Birmingham in the UK. "That is only partially true. It's much more important to remove bacteria from the teeth."

英国伯明翰大学副教授、修复牙科学专家约瑟芬·赫希菲尔德说：“很多患者知道刷牙需要清除食物残渣。他们只说对了一半。事实上，清除牙齿上的细菌要重要得多。”

These bacteria and other microorganisms grow inside everyone's mouth, and form a claggy biofilm commonly known as dental plaque. It is made up of around 700 different species of bacteria, the second-greatest diversity in the human body after the gut, as well as a host of fungi and viruses. "They are living in the sticky film stuck to the teeth and also to the soft tissues," says Hirschfeld. "This sticky film can't be easily rinsed off – it really needs to be manually cleaned."

这些细菌和其他微生物在每个人的口腔内生长，并形成称为牙菌斑的粘稠生物膜。它由大约700种不同的细菌组成，细菌多样性在人类体内仅次于肠道，还有大量的真菌和病毒。赫希菲尔德说：“它们生活在粘附在牙齿和软组织上的粘性膜中。这种粘性膜不能轻易被冲洗干净——它真的需要手动清洁。”

The most important place to remove it from is not in fact the teeth, but the gumline. This is where microbes are best able to infiltrate the gum tissue and cause inflammation, and eventually conditions such as periodontitis. In fact, "brushing your teeth" is something of a misnomer. "Think of brushing your gumline, rather than the teeth themselves," says Hirschfeld. "The teeth will then be brushed automatically."

最该清洁的部位实际上不是牙齿，而是牙龈。这是微生物最容易入侵牙龈组织并引发炎症的地方，最终可能导致牙周炎等病症。实际上，“刷牙”这个词有点用词不当。赫希菲尔德说：“刷牙该刷的是牙龈，而不是牙齿本身。在刷牙龈时牙齿也会被刷到。”

Brushing too hard, especially with a firmer-bristled brush, can cause trauma to the gums. Small tears in the soft tissue caused by overzealous brushing are an opportunity for bacteria to enter the bloodstream. And grating the brush's bristles over the enamel can wear miniscule grooves in the tooth, which add up to significant erosion over time.

刷牙太用力，特别是使用硬毛牙刷，可能会对牙龈造成创伤。过度用力刷牙造成的软组织小撕裂让细菌有了进入血液的机会。而且，牙刷硬毛在牙釉质上磨擦会磨出微小的凹槽，随着时间的推移，这些凹槽会累积成显著的侵蚀。

There are some toothbrushes and toothpastes on the market that will literally "brush the teeth away", says Hirschfeld. Highly abrasive toothpastes, which are often marked as "whitening", and hard-bristled brushes are notorious for this, particularly when used together.

赫希菲尔德说，市场上有一些牙刷和牙膏真的会“把牙齿刷掉”。通常标有“美白”字样的高研磨性牙膏，如果再加上臭名昭著的硬毛牙刷，可谓是“事半功倍”。

Is it better to brush your teeth before or after breakfast? It depends on what you've had to eat. Acidic food and drink – such as citrus fruit, fruit juice and coffee – would be a reason to brush before rather than after breakfast.

早餐前还是早餐后刷牙更好？这取决于你早餐吃什么。如果你早餐要吃酸性食物和饮料，如柑橘类水果、果汁和咖啡，那么你应该在早餐前而不是早餐后刷牙。

Acids attack the enamel layer of the teeth and soften it for a certain amount of time. This strips out some of the key components of the enamel – calcium and phosphate – though these are replaced over a period of hours by minerals in the saliva. But if you don't wait for that self-repair to happen, then this eroded surface will become very susceptible to just being brushed off.

酸性物质会攻击牙釉质并使其软化一段时间。牙釉质的一些关键成分——钙和磷——会被剥离，过几个小时等唾液分泌出替代的矿物质才能恢复。但如果你不等牙齿的自我修复完成就刷牙，那么这个被侵蚀的牙釉质就会非常容易被刷掉。

More important than the breakfast question is the evening brush, which also has a simpler answer: it should always happen last thing before bed.

相比早餐前还是早餐后刷牙的问题，晚上刷牙的问题更重要，答案也更简单：刷牙永远应该是睡觉前做的最后一件事。

"Your saliva is your natural protective mechanism," says Nigel Carter, chief executive of the Oral Health Foundation in the UK, inhibiting bacterial growth and tooth decay. "The saliva flow reduces overnight, so that's why it's very important that all the plaque is cleared away before you sleep."

英国口腔健康基金会首席执行官奈杰尔·卡特说：“你的唾液是你的天然保护机制，”可以抑制细菌生长和蛀牙。“唾液流动在夜间减少，这就是为什么在睡觉前清除所有牙菌斑非常重要。”

Spitting out toothpaste when you're finished but refraining from rinsing helps the fluoride to hang around the teeth longer, for additional protection.

刷完牙后吐出残余牙膏和泡沫但不要漱口，可以帮助氟化物在牙齿上停留更长时间，从而提供额外的保护。

英文来源：BBC

翻译&编辑：丹妮

审核：齐磊、韩鹤