中英文稿

當(dāng)一群考古學(xué)家最近發(fā)掘出?將近15000年前的人類骸骨時，?他們有了一個有趣的發(fā)現(xiàn)：?這些遠古人的牙齒上有許多蛀洞。?他們蛀牙的罪魁禍首和今天折磨我們的東西一樣，?那就是生活在我們口中的某些細菌。?這些細菌從出生時就開始伴隨著我們。?一般而言，它們是從母親的口中傳給孩子的。?當(dāng)我們的牙齒開始生長時，?它們便開始形成菌落。?我們所吃的食物?和我們所攝入的糖分，?可以使得某些細菌過度增殖并形成齲齒。?高糖飲食會導(dǎo)致我們口中?一種叫做"變形鏈球菌"的細菌爆發(fā)式的增長。?就像人類一樣，這些微生物喜歡糖類，?并將糖作為生長的基石和能量的來源。?當(dāng)細菌消耗糖類時，?它們會產(chǎn)生一種酸性的副產(chǎn)品，?比如"乳酸"。?"變形鏈球菌"可以免疫乳酸的腐蝕，?然而不幸的是，我們的牙齒并不可以。

?盡管我們每個人的牙齒上都有一層質(zhì)地堅硬，可以起到保護作用的"牙釉質(zhì)"，?但是這仍不是酸的對手。?隨著時間的推移，酸會侵蝕這層盔甲，溶解其中的鈣元素。?漸漸地，酸會為細菌侵蝕出一條通道，?直達被稱作"牙本質(zhì)"的牙齒內(nèi)層。?因為牙齒的血管和神經(jīng)都被保護在最深處，?在這個階段，逐漸擴大的齲齒并不會造成痛感。?但是一當(dāng)細菌繼續(xù)侵蝕，?超過"牙本質(zhì)"的范圍，?神經(jīng)就會被暴露，同時形成強烈痛感。?如果不加治療，整顆牙齒就會受到感染?并且需要拔除，?這都是由那些好糖類細菌導(dǎo)致的。?

攝入食物中的糖分越多，?牙齒受到的威脅就越大。?然而，那些山頂洞人幾乎不會饕餮甜食盛宴，?那么他們的齲齒是什么造成的呢？?在多肉的飲食中，形成齲齒的風(fēng)險較小，?因為瘦肉中包含很少的糖分。?但是我們的祖先不僅僅只吃瘦肉，?山頂洞人還會吃根類蔬菜，堅果和谷物，?這些食物都包含碳水化合物。?當(dāng)碳水化合物暴露在唾液中酶的環(huán)境時，?它們便會被分解更為簡單的糖，?這為那些貪婪的細菌提供了養(yǎng)分。?

所以盡管我們的祖先相較我們攝入了更少的糖分，?但他們的牙齒仍暴露在糖分之中。?雖然如此，這并不代表他們不能治療齲齒。?考古遺跡顯示在約14000年前，?人類已經(jīng)會使用磨尖的燧石去除爛牙。?遠古人甚至做了最原始的鉆頭?用于磨平留下的粗糙的齲洞，?并將蜂蠟注入蛀孔，就如今天的填充物一樣。?如今，我們有了更加成熟的技術(shù)和工具，?這是非常幸運的，因為我們需要面對更具破壞性的?更多糖分的飲食。?工業(yè)革命后，人類齲齒發(fā)生率飆升，?這是因為突然之間我們有了更加先進的技術(shù)?使得精煉糖變得更加便宜和易得。

?今天，92%的美國成年人有齲齒問題，難以置信。?某些人由于基因更易形成齲齒，?這些基因會導(dǎo)致如更軟的"牙釉質(zhì)"等問題，?但是對于大多數(shù)人而言，高糖的攝入才是罪魁禍首。?但是，我們已經(jīng)發(fā)展出了?降低糖類和淀粉攝入之外減少齲齒的辦法。?在大部分的牙膏和自來水中，?我們添加了少量的氟化物。?氟化物可以增強牙齒并促使牙釉質(zhì)生長?以抵抗酸的侵蝕。?當(dāng)齲齒已經(jīng)產(chǎn)生時，?我們利用牙齒填充物去填補并封閉被感染區(qū)域，?防止它們朝著更壞的方向發(fā)展。?

然而，預(yù)防齲齒的最佳方式仍是降低糖分攝入，?形成良好的口腔衛(wèi)生，?以消除細菌和它們的食物來源。?這包含日常的刷牙，?剔牙，?避免攝入糖類?淀粉?和在各餐之間會附著于牙齒上的粘性食物。?漸漸地，口腔中的好糖類細菌便會減少。?和以前的山頂洞人不同，?今天的我們擁有更多預(yù)防齲齒的知識。?我們只需運用它。

When a team of archaeologists recently came across?some 15,000 year-old human remains,?they made an interesting discovery.?The teeth of those ancient humans were riddled with holes.?Their cavities were caused by the same thing that still plagues us today,?specific tiny microbes that live in our mouths.?These microbes are with us soon after birth.?We typically pick them up as babies from our mothers' mouths.?And as our teeth erupt,?they naturally begin to accumulate communities of bacteria.?Depending on what we eat,?and specifically how much sugar we consume,?certain microbes can overpopulate and cause cavities.?Diets high in sugary foods cause an explosion of bacteria?called mutans streptococci in our mouths.?Like humans, these microorganisms love sugar,?using it as a molecular building block and energy source.?As they consume it,?the bacteria generate byproducts in the form of acids,?such as lactic acid.?Mutans streptococci are resistant to this acid,?but unfortunately, our teeth aren't.?While each human tooth is coated in a hardy, protective layer of enamel,?it's no match for acid.?That degrades the armor over time, leaching away its calcium minerals.?Gradually, acid wears down a pathway for bacteria?into the tooth's secondary layer called the dentin.?Since blood vessels and nerves in our teeth are enclosed deep within,?at this stage, the expanding cavity doesn't hurt.?But if the damage extends beyond the dentin,?the bacterial invasion progresses?causing excruciating pain as the nerves become exposed.?Without treatment, the whole tooth may become infected?and require removal?all due to those sugar-loving bacteria.?The more sugar our food contains,?the more our teeth are put at risk.?Those cavemen would hardly have indulged in sugary treats, however,?so what caused their cavities??In meat-heavy diets, there would have been a low-risk of cavities developing?because lean meat contains very little sugar,?but that's not all our early human ancestors ate.?Cavemen would also have consumed root vegetables, nuts, and grains,?all of which contain carbohydrates.?When exposed to enzymes in the saliva,?carbohydrates get broken down into simpler sugars,?which can become the fodder for those ravenous mouth bacteria.?So while ancient humans did eat less sugar compared to us,?their teeth were still exposed to sugars.?That doesn't mean they were unable to treat their cavities, though.?Archaeological remains show that about 14,000 years ago,?humans were already using sharpened flint to remove bits of rotten teeth.?Ancient humans even made rudimentary drills?to smooth out the rough holes left behind?and beeswax to plug cavities, like modern-day fillings.?Today, we have much more sophisticated techniques and tools,?which is fortunate because we also need to contend with our more damaging,?sugar-guzzling ways.?After the Industrial Revolution, the human incidence of cavities surged?because suddenly we had technological advances?that made refined sugar cheaper and accessible.?Today, an incredible 92% of American adults have had cavities in their teeth.?Some people are more susceptible to cavities due to genes?that may cause certain weaknesses, like softer enamel,?but for most, high sugar consumption is to blame.?However, we have developed other ways of minimizing cavities?besides reducing our intake of sugar and starch.?In most toothpastes and many water supplies,?we use tiny amounts of fluoride.?That strengthens teeth and encourages the growth of enamel crystals?that build up a tooth's defenses against acid.?When cavities do develop,?we use tooth fillings to fill and close off the infected area,?preventing them from getting worse.?The best way to avoid a cavity is still cutting down on sugar intake?and practicing good oral hygiene?to get rid of the bacteria and their food sources.?That includes regular tooth brushing,?flossing,?and avoiding sugary,?starchy,?and sticky foods that cling to your teeth between meals.?Gradually, the population of sugar-loving microbes in your mouth will decline.?Unlike the cavemen of yesteryear,?today we have the knowledge required to avert a cavity calamity.?We just need to use it.