你应该多久刷一次牙？以下是专家的一些提示

A lot of us are familiar with the advice that we should brush our teeth twice a day, and for at least two minutes each time. Many of us overestimate how long we brush our teeth for -- by as much as a whole minute in some cases. And yet there's some evidence that even two minutes of teeth brushing may not be enough.

According to research, to remove as much plaque as possible more is better -- with the best results at three to four minutes. Does that mean we should double our brushing time?

Dentists began recommending we should brush our teeth for two minutes in the 1970s, and later on, to use a toothbrush with soft bristles. However, today's consensus is mostly based on studies published since the 1990s, which looked at brushing times, techniques and toothbrush type.

These studies showed two minutes of brushing led to good (but not excellent) plaque reduction. But, while brushing longer than two minutes is shown to remove more plaque, there's still a lack of research which has looked at whether more than two minutes of brushing is linked with better long-term oral health compared with two minutes.

However, based on what we know of the harms of plaque overgrowth, it's likely that removing more of it each time we brush is linked to better oral health. It's also important to note that this lack of evidence is because long-term studies can be difficult to conduct.

When we brush our teeth, we do so with the main aim of removing microbes (known as dental plaque) from tooth surfaces. This plaque is an accumulation of bacteria, fungi and viruses that live together in a community known as a microbial biofilm. Biofilms are very sticky and can only be removed by brushing.

Many things can make it easier for these microbes to grow, including rough areas on the tooth's surface (such as from some fillings), being unable to reach certain areas with a toothbrush (like the spaces between teeth) or having braces. In fact, plaque biofilms re-grow on our teeth within hours of brushing -- which is why we're advised to brush twice a day.

Not brushing our teeth properly or for long enough can lead to higher levels of plaque, which may ultimately activate our body's immune response -- eventually leading to inflammation and conditions such as gingivitis. Inflammation is usually not painful, but often causes bleeding gums when brushing and sometimes bad breath. Biolfilms can also cause tooth decay.

Proper technique

The aim of brushing our teeth is to reduce as much plaque on each tooth as possible.

Current evidence suggests that spending more time brushing -- up to four minutes each time you brush -- leads to cleaner teeth. This longer brushing time means we can more effectively clean our teeth and get those hard-to-reach places.

But be careful not to brush too often (such as more than two times a day) and avoid brushing hard or using abrasive toothpastes and brushes, as this can also cause damage to our teeth and gums -- especially when using a toothbrush with hard bristles or abrasive toothpastes.

There are many different brushing techniques you can use to brush your teeth properly. One of the most recommended ones is the modified "Bass" technique, which is intended to clean at and below the gum line -- the area where plaque forms first and is most likely to cause inflammation.

You should always brush your teeth with a gentle force -- though precisely how hard this should be is currently not conclusive. Gentle brushing is preferred so that we don't damage the hard and soft tissues in our mouth.

Many factors can affect which type of technique, brush and toothpaste or floss you use. For example, people who may have damaged the surface of their teeth from drinking too many acidic fizzy drinks may have weaker teeth.

This may mean they're more susceptible to further tooth damage if they use abrasive toothpastes and harder bristles. It's worth consulting your dentist to know what you should use to brush.

Interdental cleaning -- which most of us know simply as flossing -- is also recommended alongside brushing our teeth. Studies have found that both tooth decay and gingivitis can be reduced by flossing.

The most effective way of flossing is sliding the floss between the gums and tooth and holding it firmly against the tooth -- such that the floss "hugs it" -- and rubbing along the surface of the tooth in a gentle up and down motion, gently advancing the floss beneath the gum line.

Interdental brushes, which can be pushed between the teeth at the gum level, can be even more effective. Less is known about other cleaning aids -- including toothpicks, water jets or tongue cleaners -- and how effective they are.

While we may be used to the advice that we should brush our teeth twice a day for two minutes each time, it's important that we also concentrate on using proper technique to ensure that we're brushing thoroughly and properly. Brushing for longer than two minutes may also help us ensure that we remove more plaque from our teeth -- which will likely lead to better dental health.

Josefine Hirschfeld is an academic clinical lecturer in restorative dentistry at the University of Birmingham.

Republished under a Creative Commons license from The Conversation.

你应该多久刷一次牙？以下是专家的一些提示

我们很多人都熟悉每天刷牙两次，每次至少两分钟的建议。我们中的许多人高估了我们刷牙的时间——在某些情况下甚至高估了整整一分钟。然而，有一些证据表明，即使刷牙两分钟也可能不够。

根据研究，去除尽可能多的牙菌斑会更好——在三到四分钟内取得最佳效果。这是否意味着我们应该将刷牙时间加倍？

牙医在 1970 年代开始建议我们应该刷牙两分钟，后来使用软毛牙刷。然而，今天的共识主要基于 1990 年代以来发表的研究，这些研究着眼于刷牙时间、技术和牙刷类型。

这些研究表明，刷牙两分钟可以很好地（但不是很好）减少牙菌斑。但是，虽然刷牙时间超过两分钟被证明可以去除更多的牙菌斑，但仍然缺乏研究，看看与两分钟相比，刷牙时间超过两分钟是否与更好的长期口腔健康有关。

然而，根据我们对牙菌斑过度生长危害的了解，每次刷牙时清除更多牙菌斑可能与更好的口腔健康有关。同样重要的是要注意，缺乏证据是因为长期研究可能难以进行。

我们刷牙的主要目的是去除牙齿表面的微生物（称为牙菌斑）。这种斑块是细菌、真菌和病毒的积累，它们共同生活在一个称为微生物生物膜的社区中。生物膜非常粘，只能通过刷子去除。

许多事情可以使这些微生物更容易生长，包括牙齿表面的粗糙区域（例如某些填充物）、无法用牙刷触及某些区域（例如牙齿之间的空间）或佩戴牙套。事实上，牙菌斑生物膜会在刷牙后数小时内重新生长在我们的牙齿上——这就是我们建议每天刷牙两次的原因。

不正确刷牙或刷牙时间不够长会导致牙菌斑水平升高，这可能最终激活我们身体的免疫反应——最终导致炎症和牙龈炎等疾病。炎症通常不会引起疼痛，但经常会导致刷牙时牙龈出血，有时还会导致口臭。生物膜也会导致蛀牙。

正确的技术

刷牙的目的是尽可能减少每颗牙齿上的牙菌斑。

目前的证据表明，花更多的时间刷牙——每次刷牙最多四分钟——会使牙齿更干净。更长的刷牙时间意味着我们可以更有效地清洁牙齿并清洁那些难以触及的地方。

但要注意不要刷得太频繁（比如一天两次以上），避免用力刷牙或使用磨砂牙膏和刷子，因为这也会对我们的牙齿和牙龈造成伤害——尤其是在使用硬毛牙刷时或磨砂牙膏。

您可以使用许多不同的刷牙技巧来正确刷牙。最受推荐的方法之一是改良的“Bass”技术，旨在清洁牙龈线及其下方——牙菌斑首先形成且最有可能引起炎症的区域。

您应该始终以轻柔的力量刷牙——尽管目前尚无定论。最好轻柔地刷牙，以免损伤口腔中的硬组织和软组织。

许多因素会影响您使用哪种技术、刷子和牙膏或牙线。例如，因饮用过多酸性碳酸饮料而损坏牙齿表面的人可能牙齿较弱。

这可能意味着，如果他们使用磨蚀性牙膏和较硬的刷毛，他们更容易受到进一步的牙齿损伤。值得咨询您的牙医以了解您应该使用什么刷牙。

牙间清洁——我们大多数人简称为使用牙线——也建议与刷牙一起使用。研究发现，使用牙线可以减少蛀牙和牙龈炎。

使用牙线最有效的方法是在牙龈和牙齿之间滑动牙线并将其牢牢固定在牙齿上——这样牙线就会“拥抱它”——然后沿着牙齿表面轻轻上下摩擦，轻轻推进牙龈线下方的牙线。

可以在牙龈水平的牙齿之间推动齿间刷，甚至可以更有效。对其他清洁辅助工具——包括牙签、喷水器或舌头清洁器——以及它们的有效性知之甚少。

虽然我们可能习惯于每天刷牙两次，每次两分钟的建议，但重要的是我们还需要专注于使用正确的技术来确保我们刷得彻底和正确。 刷牙时间超过两分钟也可以帮助我们确保从牙齿上去除更多的牙菌斑——这可能会导致更好的牙齿健康。

Josefine Hirschfeld 是伯明翰大学修复牙科的学术临床讲师。

根据 The Conversation 的知识共享许可重新发布。