From a dental health perspective, it's best to brush your teeth after a meal. The bacteria that live in your mouth are particularly good at metabolizing sugar and by brushing your teeth after a meal, you're removing the food for the bacteria to eat. These bacteria can result in dental carries (cavaties), which is obviously bad for your dental health, but also increases the likely hood of inflammation throughout your body. This is the reason gum disease is linked to so many other diseases.

As for before a meal, there's no reason you can't give yourself a thorough water rinse or even a toothpaste-less brush if you just want to "freshen up" before breakfast.

Bonus points: brushing afterwards also decreases the chance that you'll eat more (because you'll have the toothpaste taste in your mouth) and so brushing after meals is also a great way to thwart grazing throughout the day.

Plaque that builds-up in the heart and arteries is the same plaque that lives on teeth. Brushing BEFORE breakfast would reduce the amount of plaque actually swallowed. Brushing again afterward removes the food so that the bacteria that remains (there will always be some!) will not have sugars to feed upon, and as a result the bacteria do not proliferate as fast or as much. jmho

While many of the answers are correct there is a alternative theory out there. Brushing before eating will reduce the existence of biofilm. Biofilm harbors the harmful bacteria waiting to feast on your breakfest. If the biofilm is removed there is nothing for your food to stick to. Unless, of course, you have open embrasusres, deep pits and fissures, or crowded teeth where food will impact and be waiting for those little buggers when they rebuild.

Brushing throughly twice daily and flossing once a day is usually the best defense. Before or after a meal. It's a case of biofilm and preference.

Brushing before eating breakfast has been proven to reduce the harmful plaque that causes tooth decay. Plus, you'll be able to taste your breakfast much better after brushing the germs out of your mouth and taste buds. Once you've eaten, just chew some sugar-free gum or swish your mouth out with water and you'll be just fine.

While I agree that brushing after breakfast is correct, I would just add that if you drink coffee or tea and are worried about staining, it is best to brush after a meal rather than before. That having been said, I always brush or at least rinse before breakfast as it makes my breakfast taste so much better.

It is important that you brush twice a day with a toothpaste containing fluoride. The best times are before breakfast and last thing at night before you go to bed.

Eating and drinking naturally weakens the enamel on your teeth, and brushing straight afterwards can cause tiny particles of enamel to be brushed away. It is best not to brush your teeth until at least one hour after eating.

It is especially important to brush before bed. This is because the flow of saliva, which is the mouth’s own cleaning system, slows down during the night and this leaves the mouth more at risk from decay.

So brush away in the morning and night. Try to limit yourself directly after meals.

Lots of interesting answers. So, it seems that brushing both before and after are beneficial. I wonder if there are any downside to brushing too often.

The best is to brush before and after your every meal ;) And it is important that you brush your teeth as the first thing in the morning as bacteria gets accumulated in the mouth. It won't be nice if we swallow them. You can also opt to brush your teeth before you go to sleep because the particles accumulated in the mouth especially in between the teeth will help bacteria to thrive there the entire night. It is said that saliva has the property to fight against bacteria. Unfortunately when we sleep the production of saliva is not possible. So, it is a must to brush twice when you wake up from bed and before you leave to bed :)

Brushing your teeth first thing in the morning is the best.  A lot of plaque builds up in your mouth while you sleep.  It needs to be cleaned off as soon as possible.  If you eat breakfast pretty soon after you wake up, then I would wait to brush my teeth until after breakfast.  But if you're up fo ra few hours before eating breakfast, be sure to brush first.

Brush teeth before bed, definitely. No sense in sleeping with plaque.  Morning, well that depends, if you forgot to brush your teeth the night before, than brush them in the morning after breakfast, having toast crumbs or scrambled eggs in between your teeth is not fashionable at this time. In between these times it's your call.  Brush if you feel it is necessary or rinse your mouth with mouthwash or clean water to clear the mouth of any odours that might occur during your meal times.  Flossing is also a wonderful and necessary companion to your tooth brushing regimen to help prevent possible food build-up that hides in between the teeth causing decaying odours.

I have to say the obvious response for most people would be brushing after you eat. However, in the case of breakfast, me personally I can't go two or three minutes after waking up without brushing, then after breakfast "if time allows for breakfast" I have to brush again before I leave the house. I would assume after sleeping we need to rid of the built up germs and bacteria as soon as possible; but I doubt it would hurt to brush more than just before or just after.

After every meal is best.

I think it would be better to brush your teeth after eating breakfast. Personally, I have experienced having a bad breath every morning and I just wash my mouth. After eating I brush my teeth because how many hours that I would face and talk to other people.

Just to be sure, brush before and after eating. But seriously, it is better to brush after eating. Imagine brushing before eating breakfast, than eating, then not brushing, then going to work. Imagine what you would feel going out after eating without brushing. Brushing after eating breakfast, or even lunch and dinner is the best way to take care of your teeth.

Brushing before you eat breakfast is best.  The brushing before not only removes the plague but the toothpast or cleasning product protects your teeth.  Brushing before you go to sleep is also good as it removes the plague accumulated through your day.  While you sleep the bacteria can work it's way into your gums causing potential future problems.   If you can't brush throughout the day, flossing helps or a carry a travel size mouthwash and swish.....

Iris

Brushing your teeth before eating breakfast is beneficial, it helps in keeping your mouth fresh and germ free

It is better to brush after breakfast - or any other meal. This keep bits of food from sitting between your teeth for hours until your next meal. If your mouth needs refreshing when you first wake up a quick swish with baking soda, on a brush or in water, will clear out morning breath. - If you notice an odd taste in the morning it could be the mix of vitamen C and Fluride (sp?) - again a rinse or brush with baking soda first will clear this away, and has the effect of bubbling the breakfast food particles loose.

I've written an article in response to this question:

Techniques for Properly Brushing Your Teeth

As adults, our teeth are pretty important. They don't grow back, and they let us really enjoy that steak dinner or air-popped popcorn for dessert. The most important rule of making your toothbrush time count is that the longer you go without eating or drinking after you brush, the longer your tee... — continue reading...

I've written an article in response to this question:

Is It Better to Brush Your Teeth Before or After Eating? It's a Case of Biofilm.

What exactly they are brushing off and why — continue reading...