What if you didn’t brush your teeth for a year? - Justin Merritt · TED-Ed
本视频追踪长期不刷牙不使用牙线对牙齿、牙龈、微生物群及整体健康的影响。通过模拟时间线，揭示口腔菌群失衡如何导致口臭、牙菌斑、牙龈炎乃至龋齿。适合练习健康科普类听力与相关词汇。
10 out of 10 dentists agree that you should brush twice and floss once every day.
10位牙医里有10位都认为，你应该每天刷两次牙并用一次牙线。
But what if you just...
但如果你就是……
didn’t?
不这么做呢？
What would happen if you stopped doing any oral hygiene?
如果你完全不做口腔清洁会怎样？
And how long would it take for your mouth to get messy?
你的口腔需要多久会变得一团糟？
Let’s start with the last day you do brush and floss.
让我们从你最后一次刷牙用牙线的那天说起。
This routine doesn't actually clean your mouth completely.
这套流程其实并不能完全清洁你的口腔。
Rather, you’re maintaining a delicate balance between hundreds of microbial species.
相反，你是在数百种微生物之间维持一种微妙的平衡。
At any given time, most of these microorganisms fit into one of two groups: commensals and pathobionts.
在任何时候，这些微生物大多属于两类之一：共生菌和条件致病菌。
High quantities of commensals are good for oral health.
大量的共生菌对口腔健康有益。
They minimize inflammation, protect our mouths from harmful foreign microbes, and produce ammonia, which neutralizes tooth-decaying acids.
它们能减少炎症，保护口腔免受有害外来微生物侵害，并产生氨来中和导致蛀牙的酸性物质。
Meanwhile, an abundance of pathobionts is bad for oral health.
与此同时，过多的条件致病菌则对口腔健康有害。
Sugar-eating varieties produce acid that damages the mouths’ tissues, and meat-eating varieties thrive on the debris inflammation creates.
嗜糖类会产生酸，损害口腔组织；而嗜肉类则会在炎症产生的残渣中大量繁殖。
Thorough brushing and flossing remove members of both groups, but commensals can proliferate faster, so they tend to bounce back quicker.
彻底刷牙和使用牙线会清除两类细菌，但共生菌繁殖更快，因此往往恢复得更迅速。
This means daily oral hygiene keeps your commensal population higher than your pathobiont population.
这意味着日常口腔清洁能让共生菌数量持续高于条件致病菌。
Most oral disease is the result of this balance being disrupted, and that happens pretty quickly once you stop brushing and flossing.
大多数口腔疾病都是这种平衡被打破的结果，而一旦你停止刷牙用牙线，这种情况很快就会发生。
For the first 72 hours, the most notable side effect is supremely bad breath.
在最初的72小时内，最明显的副作用是极其严重的口臭。
But by day four, hordes of pathobionts have coated most of your teeth in a sticky film called dental plaque.
但到了第四天，成群的条件致病菌会在你的大部分牙齿上覆盖一层黏糊糊的薄膜，这就是牙菌斑。
Over the following days, the plaque triggers an immune response that causes your gums to bleed and inflame— an uncomfortable condition known as gingivitis.
随后的几天里，牙菌斑会引发免疫反应，导致牙龈出血和发炎——这种不舒服的状况被称为牙龈炎。
After a month, your booming pathobiont population may be releasing enough acid byproducts to break down enamel and begin causing cavities.
一个月后，激增的条件致病菌可能会释放出足够的酸性副产物，破坏牙釉质并开始导致蛀牙。
But the bigger problem is that your pathobionts far outnumber your commensals.
但更大的问题是，你的条件致病菌数量远远超过了共生菌。
Since both microbe communities grow at an exponential rate, even if you started brushing again, pathobionts would always have a numerical advantage.
由于两种微生物群落都以指数级速度增长，即使你重新开始刷牙，条件致病菌也始终会保持数量优势。
Researchers are investigating ways to add commensals back into the microbiome, but currently there’s no way to remodel a mouth that’s been overcome by pathobionts.
研究人员正在探索如何将共生菌重新引入微生物群，但目前还没有办法重塑一个被条件致病菌占据的口腔环境。
In this new world order, pathobionts divide and conquer.
在这种新的秩序下，条件致病菌会分裂并占领阵地。
Some pump out acids that dissolve the minerals in your teeth and drive dental decay, making them sensitive to pressure and temperature.
有些会释放酸，溶解牙齿中的矿物质并导致蛀牙，使牙齿对压力和温度变得敏感。
Others lead the gums to swell and recede, creating gaps that get colonized by yet more plaque.
还有一些细菌会导致牙龈肿胀萎缩，形成缝隙，让更多牙菌斑在此安家落户。
Over the following months, this cycle breaks down the gum’s soft tissues, advancing your gingivitis into first stage periodontitis— a painful infection of the gums.
接下来的几个月里，这种循环会破坏牙龈软组织，让你的牙龈炎发展成牙周炎初期——这是牙龈的一种疼痛感染。
This loose gum tissue feeds the meat-eating pathobionts, perpetuating their cycle of destruction.
这些松动的牙龈组织会滋养嗜食肉类的致病共生菌，让它们的破坏循环持续下去。
But the food you add to this environment also has a huge impact.
但你在这个环境中摄入的食物也有巨大影响。
The more sugar a diet contains, the more acid-producing pathobionts it supports— all of which release destructive waste that further inhibits the growth of commensals.
饮食中含糖量越高，就越容易滋生产酸致病菌——它们都会释放破坏性废物，进一步抑制共生菌的生长。
After roughly a year without brushing, your gums have been inflamed so long that the body’s immune response starts impacting the underlying bone.
大约一年不刷牙后，你的牙龈长期发炎，身体的免疫反应开始影响深层骨骼。
This process, called alveolar bone resorption, makes the jawbone recede and weakens the scaffolding holding your teeth, leaving them to wobble and fall out.
这个过程称为牙槽骨吸收，会导致颌骨萎缩，削弱固定牙齿的支撑结构，让牙齿松动脱落。
This kind of tooth and bone damage is permanent, but tooth loss isn't the end of this unhygienic journey.
这种牙齿和骨骼的损伤是永久性的，但牙齿脱落并非这段不洁之旅的终点。
In this advanced stage of periodontitis, areas of injured tissue have formed below the gum line that give pathobionts access to your bloodstream.
在牙周炎的这个晚期阶段，牙龈线下形成的损伤组织区域让致病菌得以进入你的血液循环。
From here, these bacteria can worsen health conditions throughout the body, including cardiovascular disease, kidney disease, diabetes, and arthritis.
从这里开始，这些细菌会加剧全身的健康问题，包括心血管疾病、肾脏疾病、糖尿病和关节炎。
In some cases, they can even exacerbate neurodegenerative diseases like Alzheimer’s and accelerate the growth of malignant tumors.
在某些情况下，它们甚至可能加重阿尔茨海默病等神经退行性疾病，并加速恶性肿瘤的生长。
Thankfully, there’s a simple way to avoid this grim outcome.
幸运的是，有个简单方法可以避免这种糟糕结局。
If you picked up these tools 2 or 3 weeks into our unhygienic experiment, you could have fully reversed the early stages of gingivitis and tooth decay and avoided all the permanent damage that followed.
如果你在我们这个不洁实验进行到第2或3周时拿起这些工具，本可以完全逆转牙龈炎和蛀牙的早期阶段，避免后续所有永久性损伤。
Better yet, brushing with even coverage for two minutes at a time will help your teeth make the most of your toothpaste’s fluoride, which replaces some of your exposed enamel with acid-resistant fluorine atoms.
更棒的是，每次刷牙两分钟且全面覆盖，能帮助牙齿充分利用牙膏中的氟化物——它会用抗酸的氟原子替换部分暴露的牙釉质。
So remember, brushing for two minutes twice a day will keep the pathobionts at bay.
所以请记住，每天刷牙两次、每次两分钟，就能让致病菌无从下手。