Using mouthwash before brushing is safer for your teeth because using it afterwards can be counterproductive and reduce the cavity preventative effects.
Those two statements may sound extreme but once you understand our reasoning it will all make sense. You will start using a mouth rinse before you brush your teeth after you finish reading our explanation.
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Mouthwash before brushing is safer
Using mouthwash before brushing your teeth is safer for your enamel because it neutralizes mouth acids and raises the pH back to neutral. That can prevent enamel erosion especially if your mouth is in an acidic state such as after having acidic foods, acidic drinks, or vomiting.
Prevent enamel erosion by rinsing
Brushing your teeth while your mouth is in an acidic state can result in enamel erosion. That is why Columbia University recommends waiting at least 30 minutes before you brush especially if you consumed some type of acidic food.
Immediately after eating, the mouth will become very acidic due to two reasons:
The acid residue can be from the acidic foods or beverages you just consumed.
The digestive enzymes in the saliva will also lower the oral pH.
It's harmful to brush your teeth when there is a lot of residual acid in the mouth because you'll be brushing the acid directly into your enamel. That can be a recipe for eroded enamel (demineralization) because the acid is potent enough to dissolve your enamel.
Are you in disbelief?
Well there are plenty of enamel erosion examples that'll make you a believer.
Bulimia teeth damage. A major symptom of those suffering from bulimia nervosa is dental erosion. The constant vomiting results in potent stomach acid coming into contact with tooth enamel thus eroding it.
Morning sickness enamel erosion. Pregnant women suffering from severe morning sickness can end up with similar symptoms as those with bulimia. That is why the ACOG recommends that pregnant women rinse with baking soda to neutralize the stomach acids in order to protect the enamel from erosion.
Mouthwash neutralizes mouth acids
Mouthwash can neutralize acids in the mouth and protect your teeth via 3 mechanisms.
Buffering. The ACOG recommendation of using baking soda to neutralize acid was probably influenced by the body's natural bicarbonate buffering system in saliva. The mouth can be buffered by converting the acidic H+ ions into other types of molecules.
Diluting. Mouthwash will dilute the oral environment by introducing a large volume of water and liquids into the mouth.
Rinsing. The simple act of mouth rinsing will wash away residual acids from the teeth, gums, and mouth. The mouthwash will cleanse the surfaces of your teeth.
Studies have shown that even rinsing with an alcohol based mouthwash will raise the pH of the mouth and neutralize acids. Below is a chart showing the effects of various mouthwashes and their effect on oral pH after rinsing.
By reducing or eliminating acids from the mouth, it makes it safer for you to brush your teeth. You don't have to worry about inadvertently damaging them.
It is safer to brush your teeth in a neutral pH oral environment than an acidic one.
It is dangerous to brush your teeth in an acidic pH because it can erode your teeth.
Mouthwash after brushing is counterproductive
Using mouthwash after brushing your teeth is counterproductive for cavity prevention because it decreases the efficacy of your fluoride toothpaste.
How rinsing after brushing decreases fluoride toothpaste efficacy:
Non-fluoridated mouthwash washes away fluoride on teeth.
Fluoridated mouthwash has less fluoride than toothpaste.
The combination of these two factors will decrease the effectiveness of your fluoride toothpaste. An alternative way to think about this is that by rinsing after brushing, you're undoing the effort you just made to brush with a fluoridated toothpaste.
Washes away fluoride on teeth
After brushing your teeth with fluoride toothpaste, there will be residual fluoride left on the teeth to protect them from decay. If you rinse with a mouthwash immediately after brushing, you will wash away all of that beneficial fluoride on your teeth. Essentially you'll be undoing the effort you put in to brush with fluoride.
It is due to the rinsing away of fluoride from teeth that the NHS explicitly recommends that you should NOT rinse after brushing your teeth. Their reasoning was that rinsing will dilute and reduce the preventative effects.
To drive the point home, the NHS actually recommends that you should choose a different time to use mouthwash. If you brush in the morning, you should rinse at lunchtime. That is how seriously they take on not using any type of mouthwash immediately after brushing.
However, it is of our opinion that it is a bit excessive for the NHS to recommend not even rinse your mouth after brushing your teeth. We believe it is safer to rinse after brushing because swallowing toothpaste can be hazardous.
Mouthwash has less fluoride than toothpaste
Standard mouthwash does not have fluoride so rinsing with it will reduce the preventative effects from brushing with fluoride.
However, even using fluoridated mouth rinses will still decrease the effectiveness of tooth brushing as well. The reason is because the fluoridated versions tend to have a lower concentration of fluoride than regular toothpaste.
As you can see in the two examples above, the fluoride concentration in toothpaste is significantly higher than what is found in mouthwash.
In summary, the example above shows that toothpaste has over 7x the amount of fluoride in it than the mouth rinse counterpart. Therefore, even rinsing with a fluoridated mouthwash will still dilute the effects of toothpaste.
Rinsing with mouthwash before you brush is better than rinsing after you brush. It is safer for your teeth and it maximizes the preventative effect of your fluoride toothpaste.
If you do it the other way around, you will risk enamel erosion and also reduce the preventative effect of your toothpaste.
This is the the oral hygiene routine that our dentists in Long Island City recommend you follow in order to maximize the cavity preventative effects.
Floss your teeth.
Rinse with a mouthwash for 1-2 minutes.
Brush your teeth with a fluoride toothpaste for 2 minutes.
Do not eat or drink for at least 30 minutes afterwards.
Last but not least, don't forget to get your dental cleaning and check up twice a year!