Tradition says, “Brush after every meal.” When do you suggest brushing should be done — before or after eating? You’re probably wondering why we are asking about brushing, when you know we believe cleaning between the teeth is more important than brushing. My guess is you agree and also spread the message of cleaning between the teeth first.


But we are puzzled by all the talk of brushing after meals. A quick Internet search on Google will pull up thousands of sites that tell the public to “brush after meals.” Many are dental office instructions to patients. Ask your family, friends, co-workers and patients when they should brush and the most popular answer will be “after every meal.” Is there any science behind this concept, or is it just a tradition?

When we have asked hygienists this question, some respond, “It all depends on why you brush. Are you brushing to remove plaque or food?” As a hygienist, they are thinking “plaque.” The public thinks “food” — so they brush after eating. They don’t like to brush before eating because the toothpaste flavor alters the taste of food, especially orange juice at breakfast!


The funny thing is that toothpaste research focuses on enamel abrasion, and toothbrush research looks at plaque removal, not food removal.

There seems to be a gap between research and reality. As professionals, we focus on plaque removal; but the message consumers hear is “brush after meals to remove food.”

Back to the question: Do you brush to remove plaque or food? The equation for caries is “plaque bacteria plus a fermentable carbohydrate equals acid.” We can break the equation by removing either the plaque or the carbohydrate. Removing the plaque thoroughly before introducing the carbohydrate prevents acid production. If you brush after eating to remove the food instead, it’s after the fact and, therefore, not prevention. Brushing after the acid is produced is no longer preventive. Preventive means intervention before the event — in this case, prevention would occur before acid production, not after.


Plaque bacteria produce acid right away. According to research published by Dr. John Featherstone of UCSF, acid production occurs within seconds of bacteria’s exposure to sucrose, and salivary pH drops from a neutral of 7 to acidic 4.5 within just five minutes. It then takes 30 minutes to return to 7; so waiting till the meal is over to brush allows the bacteria ample time to produce acid.


Need more convincing? Here’s another reason to brush before meals, especially when consuming acidic beverages like orange juice or soda. Dr. Addy and a team of researcher showed that enamel erosion caused by orange juice increases the susceptibility of enamel to toothpaste abrasion. The acid softens the tooth surface. Dentin is even more susceptible to erosion from acid drinks and toothpaste abrasion. Even brushing without toothpaste after ingesting orange juice resulted in loss of enamel and dentin. These researchers conclude that brushing immediately after consuming acidic beverages should be avoided. Better to brush before.

You’ve probably seen patients who eat lots of lemons, or put only vinegar on salad, and brushed their teeth right after eating, causing erosion and abrasion and, in some cases, sensitivity.

Another tradition without supporting science suggests that brushing last thing at night is more important than brushing in the morning.


When asked, Charles Zahedi, a current UCLA School of Dentistry (Periodontics) Faculty said that, although brushing before going to bed may be convenient, he’s not sure what it achieves except to remove acid softened enamel or dentin. Since soda and alcoholic drink consumption in the evening is a common practice, it makes more sense to brush when you get home from work, before having dinner, rather than after softening the enamel with acidic foods and beverages. Flossing and brushing before going to bed should not be neglected but at least 30 minutes after you had your last meal.


It looks like our brushing traditions are just that — traditions.

Based on what we do know, however, it makes more sense to brush before eating. That way, plaque is removed before ingesting sugars, and if acidic foods and beverages are ingested, we avoid compounding the erosion with toothpaste abrasion.


What about you? Do you brush before or after meals?