0:00:02 > 0:00:04- Are you ready for our Ouch Snips? - Snip.- Ouch!- Exactly.
0:00:16 > 0:00:19To find out why we have them and how they help us,
0:00:19 > 0:00:21I'm meeting entomologist, Vince Smith.
0:00:22 > 0:00:26We've got this parasite called a Demodex mite, and with these,
0:00:26 > 0:00:27the older that you are,
0:00:27 > 0:00:29the more likely you are to have them.
0:00:32 > 0:00:34So let's see if we can find some.
0:00:34 > 0:00:37Vince is scraping the skin around my eyes to try and collect enough gunk
0:00:37 > 0:00:41to test, but he doesn't get much, so we go into my ear.
0:00:41 > 0:00:43There's a good pile of gunk on there,
0:00:43 > 0:00:44so let's see what we can find.
0:00:44 > 0:00:46I'm sort of hoping he doesn't find anything.
0:00:48 > 0:00:50- You're loaded!- Ugh, look at that!
0:00:50 > 0:00:52- Ugh!- Wow.
0:00:53 > 0:00:55It's moving!
0:00:55 > 0:00:57- Absolutely incredible. - That just came out of my ear.
0:00:57 > 0:00:59In the daytime, those mites are
0:00:59 > 0:01:02living inside the little follicles of your hair cell,
0:01:02 > 0:01:06and then during the night-time, they come out and they're moving around,
0:01:06 > 0:01:09trying to find all their mates.
0:01:09 > 0:01:12So every night, there's a bit of a party in my ear.
0:01:12 > 0:01:14# You better get this party started. #
0:01:17 > 0:01:20So these mites are pretty disgusting, but actually,
0:01:20 > 0:01:21they're not doing me any harm.
0:01:21 > 0:01:23In fact, they're useful because
0:01:23 > 0:01:25they help clean the gunk from your ear.
0:01:25 > 0:01:28We're carrying around all of these passengers, and this is just
0:01:28 > 0:01:31the start. There are many other human parasites that we've got, too.
0:01:31 > 0:01:34Time to head to the lab to meet some of Chris' little passengers.
0:01:34 > 0:01:38This time, not so friendly bacteria living in his mouth.
0:01:38 > 0:01:40Ugh!
0:01:40 > 0:01:41Does my breath smell bad?
0:01:41 > 0:01:43Yes, it does, actually.
0:01:43 > 0:01:46I'm not surprised. I haven't brushed my teeth in two days.
0:01:46 > 0:01:49- But it's all for a good cause. Isn't it, Chris?- I hope so.
0:01:50 > 0:01:52In fact, it was my idea.
0:01:52 > 0:01:57Whilst I've been brushing my teeth twice a day, as you should,
0:01:57 > 0:02:00I haven't let Chris brush his at all for two days,
0:02:00 > 0:02:03but it's all in the name of medical research.
0:02:03 > 0:02:07- My teeth feel fuzzy.- That's because Chris has a layer of plaque
0:02:07 > 0:02:10building up on them. Open wide.
0:02:10 > 0:02:14I'm going to show you why plaque isn't something you want a lot of.
0:02:14 > 0:02:15When you go to the dentist,
0:02:15 > 0:02:18you'll have had your teeth scraped like this.
0:02:18 > 0:02:21- Going anywhere nice on holiday this year, Chris?- No.
0:02:21 > 0:02:25Oh, lovely, I've been there. It's wonderful at this time of year.
0:02:25 > 0:02:27Ugh, Chris, this is disgusting!
0:02:29 > 0:02:33Plaque is a mixture of food particles, acid,
0:02:33 > 0:02:35and bacteria.
0:02:35 > 0:02:37We've all got thousands of different bacteria living in our mouths,
0:02:37 > 0:02:39and most of them are harmless,
0:02:39 > 0:02:41but there are some bad ones that can
0:02:41 > 0:02:44turn the sugars in the food we eat into acid.
0:02:44 > 0:02:47And it's this plaque acid that's the real problem.
0:02:47 > 0:02:51It eats away at the tooth enamel, and that's what tooth decay is.
0:02:51 > 0:02:53- Please, can I have my toothbrush back now?- Soon!
0:02:53 > 0:02:55There's more to show you.
0:02:56 > 0:02:59We're both going to rinse our mouths with a special blue dye that will
0:02:59 > 0:03:03show up how much plaque we have on our teeth.
0:03:03 > 0:03:05It's my brushed gnashers first.
0:03:05 > 0:03:06Ta-da!
0:03:06 > 0:03:09- Ha, you look really funny. - You look funny.
0:03:10 > 0:03:13Now, even though Xander's been brushing regularly,
0:03:13 > 0:03:17you can see some dye has stuck to his teeth, and that's all plaque.
0:03:17 > 0:03:18That makes me a bit worried,
0:03:18 > 0:03:20because I haven't brushed my teeth for over two days.
0:03:20 > 0:03:23- Ugh! Why did you do that? - It was your idea.
0:03:24 > 0:03:27Well, after a quick rinse with the blue dye,
0:03:27 > 0:03:29it's time to check out the state of my un-brushed teeth.
0:03:31 > 0:03:33Ugh!
0:03:33 > 0:03:36There's plaque everywhere.
0:03:36 > 0:03:38How did you let this happen?
0:03:38 > 0:03:41And all that plaque has built up in just two days.
0:03:41 > 0:03:42That's gross!
0:03:42 > 0:03:44I feel quite disgusting.
0:03:44 > 0:03:46- I would like my toothbrush back. - Nope.
0:03:46 > 0:03:49I want to get a much closer look at your plaque, Chris.
0:03:49 > 0:03:51Look at this.
0:03:51 > 0:03:56Wow! So, these bacteria are the ones that live in my plaque,
0:03:56 > 0:03:58and although we can't tell which are
0:03:58 > 0:03:59the good ones and which are the bad ones,
0:03:59 > 0:04:03some of them are the ones that produce the acid that is rotting
0:04:03 > 0:04:04my teeth right now.
0:04:04 > 0:04:08Yes. And if you just leave plaque, it hardens like cement.
0:04:08 > 0:04:11That's called tartar and it builds and builds.
0:04:11 > 0:04:15It can damage your gums and give you rotting teeth that look like this.
0:04:16 > 0:04:18Not a good look.
0:04:18 > 0:04:20That's it. I've had enough.
0:04:20 > 0:04:23I am going to brush my teeth.
0:04:23 > 0:04:25No, he's not.
0:04:25 > 0:04:28We've shown you that we are all carrying little passengers around
0:04:28 > 0:04:32on our bodies. Most of them are there to help, but some,
0:04:32 > 0:04:35like the bacteria you find in your mouth, eat away at your teeth,
0:04:35 > 0:04:38which is why you need to brush twice a day.
0:04:40 > 0:04:42- See you next time. BOTH:- Bye!
0:04:42 > 0:04:45- Bye!- Bye!- Bye. Bye.
0:04:45 > 0:04:47BYE!