字幕表 動画を再生する 英語字幕をプリント The average UK citizen will brush their teeth over 40,000 times in a lifetime using a staggering 80 liters of toothpaste. And such a routine parts of our everyday lives, but there is only I think about it is when it runs out. Now that’s a shame because toothpaste is fascinating stuff. Tooth care remedies have been around for thousands of years. The world’s oldest surviving formula is Egyptian and it was made from mint, flowers, salt and pepper. It dates to the 5th century AD and by all accounts it worked very well. Although it did have the nasty side effects of making your gums bleed. Having said that, it was far less hazardous than some 20th century brands. In the 2nd world war, German scientists from the nuclear industry developed a radioactive toothpaste with thorium for the domestic home market. It cleans. It kills germs. It’s radioactive. Fantastic! Now why didn't that catch on? Say thorium wasn’t a great idea but other additives were much more successful. In 1901, a dentist in Colorado Springs noticed that locals had far fewer cavities than was the norm. The reason was eventually tracked down to high natural levels of fluoride in the water. From this basic observation, fluoride quickly became the dental one additive of choice. So what goes into modern toothpaste? How does it work? Well the number one ingredient is something abrasive. You know something to scrub the pearly whites For this, toothpaste manufacturers typically use baking soda or chalk or even silica which is a refined type of sand and many add whitener, flavouring, something to make it foam. Something to bind it all together and finally fluoride. Now did you know you can make your own toothpaste out of simple household ingredients? For this recipe, all you need to do is mix three tablespoons of baking soda with 1 tablespoon of salt. Then add three teaspoons of glycerin. Mix them all together with a dash of water. And finally add 1 teaspoon of peppermint and hey presto! Do it yourself toothpaste. For a proper test of its effectiveness, I’m going to stain my teeth with licorice. I have some very sugary pop. Now it firms them up. Now my teeth feel awful so let’s put this home-made toothpaste to the test. I feel that! Gosh! Seriously, feel good. I feel much better. It tastes quite minty, very abrasive. It’s incredibly salty but it’s cleaning my teeth. I feel so much better. How about my teeth looks a little bit cleaner? Hmm. Home-made toothpaste! It works!