Wikipedia:Reference desk/Archives/Science/2020 August 6

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August 6

What's more important brushing the teeth before sleeping or after waking-up?

Obviously, it's very important and healthy to brush teeth twice a day (or after meals), But my question is about importance. Which of these two is more important, if you have only one of them to choose? (before going to sleep or after waking up) --ThePupil (talk) 06:09, 6 August 2020 (UTC)

Brushing your tooth immediately after each meal (which some people do as if it is a religious duty) is overkill; the natural production of saliva will wash away most of the stuff the bacteria causing caries thrive on, as well as most of these bacteria when they start multiplying (which they can do very rapidly). I don't know if this has been the subject of any scientific studies, but I'd think that if your mouth and teeth are meticulously cleaned before bedtime, there is not much left for the bad bacteria as a growth medium. However, they do not need much, and at night saliva production slows down significantly, so just a little amount of carbohydrates (not just sugar!) can already give rise to a significant layer of dental plaque, which is why brushing in the morning is important: if left the plaque will eventually harden into calculus, which can no longer be brushed or flossed away. So I expect the verdict to depend on the meticulosity of the pre-bedtime cleaning of one's mouth and teeth, which is hard to control in a scientific study. If this pre-bedtime cleaning is an (even mildly) sloppy job, then brushing and flossing in the morning may give the better result. But if thoroughly done before going to bed, pre-bedtime cleaning may work out better.  --Lambiam 07:33, 6 August 2020 (UTC)

Do what your dentist tells you, not what anonymous persons on the internet tell you. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:15, 6 August 2020 (UTC)

I am with Baseball Bugs on this. I also note that the above comment is a perfect example of the right way to deal with medical questions and answers on the reference desks; no attempts to make up new rules of control other people, just good, sound "do what your dentist tells you" medical advice.

There is a dentist who writes the following on the Mayo Clinic website:

"The American Dental Association recommends brushing your teeth twice a day with fluoride toothpaste for two minutes each time... In choosing when to brush your teeth, you might also consider your diet. If you've eaten an acidic food or drink, avoid brushing your teeth right away. These acids weaken tooth enamel, and brushing too soon can remove enamel.

Besides brushing your teeth, to keep your mouth healthy, do the following:

• Floss daily.
• Use mouthwash after brushing and flossing.
• Drink plenty of water.
• Eat a healthy diet and limit sugary food and drinks.
• Avoid frequent snacking.
• Replace your toothbrush every three to four months, or sooner if the bristles are irregular or splayed.
• Schedule regular dental checkups with X-rays and cleanings."[1]

Needless to say, while the expert advice of a dentist on the Mayo Clinic webpage is better than the advice of a random person on the internet, the advice of an actual dentist who is looking at your actual teeth is even better. --Guy Macon (talk) 12:08, 6 August 2020 (UTC)

For those looking for academic research on the topic, this might be of use:[2] -Guy Macon (talk) 12:14, 6 August 2020 (UTC)

That study is only about oral hygienic behaviour and does not relate it to dental health.  --Lambiam 14:09, 6 August 2020 (UTC)

The very first sentence of the question ("Obviously, it's very important and healthy to brush teeth twice a day (or after meals).") makes it clear, IMO, that the questioner is not seeking advice but is posing a hypothetical scientific question, which I attempted to treat as such.  --Lambiam 14:09, 6 August 2020 (UTC)

And, the best source for information from that hypothetical scientific question is to ask their dentist. --Jayron32 18:31, 6 August 2020 (UTC)

@Lambian, thank you for your comment, I think you understood me properly. I looked for scientific support and explanation rather than for medical advice. I want to support the answer based on scientific source and logically explained (something that many dentist can't do, unfortunately), I can't refer by "my lovely dentist said to do so". I have a sense and I want to use it and get explanations if I have the possibility to understand it. Not looking for medical advice here, not only now but never.--ThePupil (talk) 00:00, 7 August 2020 (UTC)

Do leaf serrations that don't cut or scratch human skin increase fitness?

Sagittarian Milky Way (talk) 17:47, 6 August 2020 (UTC)

Can you rephrase the question? It's confusingly worded.--Jayron32 18:29, 6 August 2020 (UTC)

Do the serrations of leaf edges increase the plant's Darwinian fitness even if they're not stiff and sharp enough to scratch human skin? Sagittarian Milky Way (talk) 19:19, 6 August 2020 (UTC)

Quora - What's the evolutionary advantage of serrated leaves vs. smooth edged leaves?: "Some researchers have hypothesized that serrated (or toothed) leaves allow for earlier (spring) photosynthesis in their growing season in temperate forests, thus giving them more time for photosynthesis before fall and winter sets in. This could be one way for certain plants to be able to gain some evolutionary advantage in temperate conditions". Alansplodge (talk) 19:22, 6 August 2020 (UTC)

The Wikipedia article titled Serration also contains other likely advantages they provide. --Jayron32 19:24, 6 August 2020 (UTC)

And a lot of things other than humans might want to do things to plants. Many plant defenses against herbivory are targeted at small mammals or arthropods. Among these: caffeine and nicotine, which poison insects and can even be used as pesticides. In fact a whole class of manmade pesticides, the neonicotinoids, are based on nicotine's structure. --47.146.63.87 (talk) 20:55, 6 August 2020 (UTC)

Some beetles

These cockroach-like beetles have recently popped up at night in a living room, Warsaw, Poland. The length is about 2 cm, prefer to crawl or sitting still, but when disturbed they fly away. What's the species? Thanks in advance. Brandmeister^talk 22:23, 6 August 2020 (UTC)

The pictures aren't clear, but they rather remind me of certain types of Ground beetle. But most of those don't fly, so that may be a mistake. Iapetus (talk) 09:30, 7 August 2020 (UTC)

In the pictures I see rather something like a Common furniture beetle, a Red flour beetle or a Firefly. And I would say that Cockroaches look rather different: they have four transparent wings while your insect seems to have elytra, the hardened forewings of true beetles (Coleoptera). 2003:F5:6F0C:E600:487C:DA02:59F5:AE62 (talk) 21:06, 8 August 2020 (UTC) Marco PB