"Brush after meals." That's the message we've heard and repeated for decades. It's not just dentists and hygienists sharing this message, toothpaste companies also tell consumers to brush after meals. But is this idea based on science or simply a tradition that has been repeated so often it's become dogma, without any scientific substance? Research shows that if the meal consists of any high acid foods or beverages brushing right after eating can be detrimental. The acids in orange juice or soda pop will actually soften enamel and dentin enough to make them susceptible to abrasion when brushed with toothpaste. Based on these findings, researchers suggest waiting 60 minutes after eating to brush. Dr. Martin Addy and his research team at the University of Bristol in the U.K. who did the acid testing suggest brushing before eating rather than after to prevent acid production.
Plaque bacteria produce acid right away. According
to research published by Dr. John Featherstone of
University of San Francisco, acid production occurs
within seconds of bacteria's exposure to sucrose or fermentable
carbohydrates. This acid production will
drop the salivary pH from a neutral of 7 to an acidic
level of 4.5 within just five minutes. It then takes 30
minutes to return to a pH of 7. Waiting to remove
bacterial plaque biofilm until the meal is over allows
the bacteria ample time to produce acid.
Brushing and flossing first thing in the morning
to remove the plaque biofilm thoroughly before
introducing fermentable carbohydrates prevents acid
production. If you wait to brush and floss your teeth
until after breakfast, it's too late. Sure, you will now
remove both bacterial biofilm and food particles, but
if you've had orange juice or other acidic foods, it
might cause microscopic damage to the enamel.
According to Dr. Addy brushing after the acid is produced
is no longer preventive. Preventive interventions
occur before the event – in this case, prevention
would occur before acid production by Strep mutans,
not after.
To consumers, brushing after meals make sense
because they equate brushing to removing food particles;
however, toothbrushing research focuses on
plaque removal, not food removal. We have no
research suggesting that toothbrushing is effective
for food removal. Food particles generally remain
between the teeth, not on the facial and lingual surfaces
reached by the toothbrush. Rinsing works to
flush out food particles, so using an oral irrigation
device after eating makes more sense than brushing
after meals.
Another tradition without supporting science
suggests that brushing last thing at night is more
important than brushing in the morning. When
asked, Addy said that, although brushing before
going to bed might 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, both in
England and the United States, 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.
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 and floss first
thing in the morning or wait until after breakfast? Base
your decision on scientific evidence, not tradition. |