What does the best and most recent scholarly data tell us about the
optimal number of times to brush you teeth in a 24 hour period.

Hi philip...

Simply, how often you should brush depends on how often you eat
or drink something, other than water, that contains starches, or
especially, sugars.

The bacteria which form plaque, which holds acids produced by
these same bacteria against your teeth, thrive on sugar. These
bacteria begin producing acids from the sugar in your mouth
within minutes of its presence. They also double in numbers
about every 20 minutes.

Starches are complex carbohydrates, vs sugars, which are simple
carbohydrates. Starches are broken down into sugar by saliva
(this is one of the main functions of saliva - it predigests
starches for absorption in the later stages of the digestive
system, the acids of which are not designed to break down 
starches, so much as proteins). So carbohydrates which are
not removed from the mouth soon turn into sugar, and feed the
bacteria whose byproducts are the acids which cause decay.

So the latest wisdom is to brush, and, if possible floss, and
if neither is feasible, to at least rinse, after every instance
of ingesting sugar or starches, as well as after every meal.

Keep in mind, of course, that there may also be hidden sugars
in many proteins, such as lunchmeat with sugar added, and that
the bread commonly used in sandwiches is a starch.

Saliva can neutralize some of the acids from the bacteria,
but this is not effective is you are sipping a sweetened
beverage at frequent intervals throughout the day.


The following are quotes from websites which, both independently
and together, substantiate what I've written above:


From the Virtual Chemistry Book at Elmhurst College:

"Sugar, saliva, and bacteria lead to a formidable
 combination that may lead to tooth decay. After
 eating sugar, particularly sucrose, and even within
 minutes of brushing your teeth, sticky glycoproteins
 (combination of carbohydrate and protein molecule)
 adhere to the teeth to start the formation of plaque.
 At the same time millions of bacteria known as
 Streptococcus mutans also adhere to the glycoprotein.
 Although, many oral bacteria also adhere, only the
 S. mutans is able to cause cavities."

"In the next stage, the bacteria use the fructose in
 a metabolism process of glycolysis to get energy.
 The end product of glycolysis under anaerobic
 conditions is lactic acid. The lactic acid creates
 extra acidity to decrease the pH to the extent of
 dissolving the calcium phosphate in the tooth enamel
 leading to the start of a cavity."
http://www.elmhurst.edu/~chm/vchembook/548toothdecay.html


From Dr. Spiller's excellent page on the topic:

"If there were no fermentable sugars in your diet, you
 would never get a single cavity. This applies even to
 the rare person who's teeth are in fact "soft". This
 also holds even if you never brush your teeth!"
[He backs this up with an example of a woman he treated]

"Almost everyone who is prone to caries has a specific
 habit in which sugar soaks the teeth many, many times
 a day. These sugar habits account for perhaps 95% of
 all caries! If you can identify the habit, and
 substitute a diet drink, or a non sugared food in its
 place, the decay simply stops where it is."

"Brushing your teeth DOES help prevent dental caries.
 In order for the sugar to have the negative effect it
 does on the teeth, the bacteria (germs) that live in
 plaque must metabolize (digest) it to produce a
 dilute ACID which is the agent that does the real
 damage to the teeth. These germs live in your mouth
 and double their number about every 20 minutes. By
 brushing your teeth, you are reducing their number,
 and hence the amount of acid produced. This in turn
 reduces the rate of decay. Unfortunately, even if
 your oral hygiene is very good, millions of germs
 remain behind, and continue to reproduce throughout
 the day leaving plenty of them around to turn the
 multiple swigs of sugar into acid. In the presence
 of reasonable oral hygiene, multiple exposures of
 the teeth to sugar still produces decay, but much
 more slowly than if the teeth are not kept clean."

"Sugar at normal mealtimes does almost no damage
 whatsoever because the exposure to the sugar is
 not prolonged and the other foods you are eating
 at the same time tend to wash the sugar off the
 teeth. Fresh fruit is rarely a problem even though
 it contains natural sugars because of the detersive
 (washing) effect of the fruit fibers."

Much more on the page:
http://www.doctorspiller.com/Tooth_Decay.htm


From the National Institutes of Health site:

"Every time we eat foods containing sugars, we get an
 acid attack that lasts approximately 20 minutes. If
 nothing else containing sugars is eaten, the saliva
 in the mouth will fight off the acid attack. However,
 if we eat frequently, especially sugars and refined
 carbohydrates, the repeated cycles of acid attack
 will cause greater tooth demineralization to occur.
 Limiting between-meal snacks will reduce the number
 of acid attacks on your teeth. Also, eating or
 drinking sweet or starchy foods between meals is more
 likely to harm teeth than eating the same foods with
 meals. Saliva production increases during meals and
 helps buffer the acids and rinse food particles from
 the mouth. It?s best to eat sweets as dessert after
 a main meal instead of several times a day between
 meals."

"Some high-sugar foods, such as candy, cookies, and
 soft drinks, provide calories but lack the nutrients
 that our bodies need. Other foods, including fruits,
 milk, yogurt, bread, cereals, and vegetables, also
 contain sugars and starches, but these foods nourish
 the body by providing important vitamins, minerals,
 and fiber."
http://science.education.nih.gov/supplements/nih2/oral-health/guide/lesson5.html


In summary, to prevent cavities, eliminate any pattern
in which you teeth are exposed to frequent and sustained
doses of sugar or simple carbohydrates.

Brush (and preferably, floss) after every major meal
(within 20 minutes, for the best results), and after
every exposure to sugar or other simple carbohydrates
(white flour is a good example). At the minimum, rinse
thoroughly after any snack, and brush after major meals.

If rinsing is not an available option, you can use 
techniques, such as the yoga technique of clicking your
upper and lower teeth together, to increase saliva 
production, and hold it in your mouth, rinsing with it.
Imagining biting into a lemon might be useful, as well.

If you must snack, and can't brush or rinse adequately,
use snacks with sugar alternatives, which don't allow
the bacteria to produce acid. Read more about this on 
Dr. Spiller's page. Near the bottom of the page, read 
how one sugar substitute, xylitol, can even help in the
prevention of tooth decay.

Also see Dr. Spiller's page for an explanation of the
benefits of fluoridated water and toothpaste.


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Additional information may be found from an exploration of
the links resulting from the Google search outlined below.

Searches done, via Google:

"tooth decay" acid minutes brush
://www.google.com/search?q=%22tooth+decay%22+acid+minutes+brush

I really would have liked some research papers sited, rather than the
opinion of dentists or material on www sites.