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  • 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.

When a team of archaeologists recently came across

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B2 US TED-Ed teeth bacteria tooth acid enamel

【TED-Ed】What causes cavities? - Mel Rosenberg

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    Lê Phước Đức posted on 2016/10/21
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