Why should I brush my teeth in the morning? My teeth are just going to get dirty again when I eat breakfast 5 minutes later. Plus, I've already done an extensive cleaning (floss, brush, mouthwash) the night before. My teeth should not be getting dirtier as I sleep.

I've heard people say their breakfast tastes better after brushing their teeth. I've never experienced bad taste from not brushing. I only care about the hygiene reasons for brushing in the morning.

  • As an aside, I recently learned that flossing is extremely important in preventing infection (that's what gingivitis is) and losing your teeth! Commented Apr 21, 2011 at 6:21
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    In addition to the other answers, not disputing them but I don't want to add on to them, there is a coating applied from toothpaste that protects your teeth from subsequent bacterial infection. There are antibiotic agents in toothpaste to protect the toothpaste itself from spoilage but also inhibit growth on the teeth themselves. This is manifested by a slipperiness you can feel.
    – geoO
    Commented Mar 26, 2013 at 0:59
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    "My teeth are just going to get dirty again when I eat breakfast 5 minutes later." So brush after you eat rather than before
    – Alexander
    Commented Mar 26, 2013 at 5:32
  • @KonradRudolph - Classic! Don't suppose you have a pic you could link to of that pamphlet?
    – user66001
    Commented Aug 13, 2014 at 20:24
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    Because when your mother asks if you've brushed your teeth this morning you don't want to lie. Commented Nov 18, 2018 at 15:57

2 Answers 2


Brushing at night is the most important. Saliva naturally fights the growth of bacteria on your teeth. Your mouth dries out at night and reduces your mouth's ability to do this. Ideally, you would keep your teeth clean at all times but that's of course not realistic. A while back I read many websites and opinions about this very question. The main consensus seemed to be that people brush in the morning because it makes them feel good to start their day with a clean mouth (not because it's the best time to do it).

Here is a discussion about it on Ask MetaFilter:

During the day, you're flapping your jaw, drinking water, chewing gum, and moving your tongue, all of which help to clean things off of your teeth. At night, your mouth is much less active, which allows bacteria more time to grow without being mechanically sloughed off.

Many years ago my orthodontist told me that it was most important to brush your teeth before going to sleep (I guess either for the night, or for a nap). Saliva production is down, and if you happen to sleep with your mouth gaping open, your teeth dry out and don't have that protective layer of saliva. Just the lack of movement of your lips and tongue while sleeping gives decay more of an opportunity to do its dirty work.

Here is an article by Dr. H.S. Chawla:

Brushing before meals: Most people normally brush their teeth in the morning before breakfast. That is beneficial, as you have reduced the number of bacteria before exposing them to food. The amount of acid production is expected to be less, and so would be the damage to the teeth. You get an additional benefit if you use fluoride tooth paste, as the fluoride gets incorporated into the enamel and makes it strong and resistant to the effect of acid. (Fluoride converts the hydroxyl-apatite of enamel to calcium fluor-apatite).

If you are going to brush in the morning, it may actually be better to brush before you eat rather than after.

brushing right after eating is not at all advised, as the acid produced [by bacteria] has already begun the process of eroding enamel. If you brush promptly after a meal, you rub off part of the dissolved minerals of the enamel.

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    Brushing teeth is a medical intervention. Medical interventions generally need controlled studies to be accepted. Your post simply lists a bunch of pseudoscientific discussion. Could you provide real sources?
    – Christian
    Commented Apr 21, 2011 at 13:16
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    I agree that brushing at night is most important, though the next sentence is BS:"your teeth dry out and don't have that protective layer of saliva" since bacteria can't live in a dry environment. Having completely dry teeth would actually be a very effective way to keep them from rotting.
    – user4513
    Commented Aug 17, 2011 at 10:43
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    A web forum discussion and a link to a blog from an institute that develops "mind power" are not good sources. Would you be willing to back this up with proper sources? Commented Oct 31, 2011 at 1:13
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    I am so confused about why this post has upvotes...Isn't this the type of post we want to downvote?
    – Jase
    Commented Dec 26, 2012 at 2:13
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    Weak, I'm downvoting for poor sources. OOps, can't, not enough rep.
    – geoO
    Commented Mar 26, 2013 at 0:59

Expanding on Logicbird's answer, here is what the British Dental Health Foundation says:

Acidic foods and drinks, such as oranges, grapefruit and fruit juices that are often eaten at breakfast time, soften the enamel on your teeth.

Brushing immediately afterward wears the enamel away, and can cause dental erosion, which may lead to pain and extreme sensitivity in the teeth, and also lead to cosmetic problems.

The saliva in your mouth neutralises the acidity and restores its natural balance. However research has shown that this can take up to an hour.

Their tips for avoiding dental erosion are:

  • brush teeth before breakfast if you have fruit or fruit juice, or

  • wait one hour after eating or drinking anything acidic before

  • use a straw when drinking acidic drinks to reduce contact with teeth

  • drink water and milk between meals in preference to juice and fizzy drinks

  • chew sugar-free gum - this will produce more saliva to help cancel
    out acid in your mouth

  • finish a meal with cheese or milk to help neutralise any acids

The NHS says the same:

Brush your teeth in the morning before breakfast and last thing at night before you go to bed (and ideally at least an hour after your evening meal).

Brushing your teeth straight after a meal can damage your teeth, especially if you've had fruit, fizzy drinks, wine or any other food that contains acid. This is because tooth enamel is softened by the acid and can be worn away by brushing. Waiting an hour gives your saliva chance to neutralise the acid.

  • If I brush my teeth before I drink an acidic juice, that means there's little plaque or saliva to prevent the juice from breaking down the enamel. So why brush before drinking?
    – JoJo
    Commented Apr 21, 2011 at 22:13
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    @JoJo - Brushing actually induces salivary secretion
    – Oliver_C
    Commented Apr 22, 2011 at 9:24
  • It says here at one point enamel get softer. Does that means that it gets harder again if you leave it alone or...?
    – user5957
    Commented Feb 1, 2012 at 22:41
  • @Amer - My dentist said that fluoride (e.g. in toothpaste) would help harden it.
    – ChrisW
    Commented Feb 2, 2012 at 0:43
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    @Amer - Here is a study saying: Rehardening effects following milk or saliva exposures respectively were evident, presumably due to deposited organic and mineral material on the enamel surface.
    – Oliver_C
    Commented Feb 3, 2012 at 15:17

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