Why brush twice a day?

You’ve heard it over and over.  Brush your teeth in the morning and before you go to bed.  Brush your teeth three times every day.  Did you ever wonder why?  Read on, because there really is a good scientific reason.

Brushing flossing and rinsing with mouthwash keeps our breath fresh and makes our mouth feel cleaner.  It accomplishes this by reducing the bacterial count in the mouth, which then reduces stains, removes food particles and slows disease development.  But why do it twice?  What is the real reason for frequent cleaning? 

In order to understand why twice a day cleaning is so important we have to look at something called biofilm formation.  What is biofilm?  It is that nasty slimy stuff that forms on hard surfaces like teeth, crowns and dentures in any warm dark wet bacteria laden environment such as the mouth.  You can really feel it when you first get up in the morning.  Biofilm is made up of bacteria and their byproducts.  Biofilm formation follows a very precise sequence, with different bacteria forming layer upon layer.  The first layer is made up of gram positive aerobes, Streptococcus and Actinomyces.  These are oxygen loving (aerobes) and non pathogenic.  In fact, they are considered beneficial, associated with healthy gums and aid in the first steps of digestion.  They do not cause gum disease.

Remember, the mouth is full of bacteria and other bugs.  Healthy gums are not sterile but colonized with healthy bacteria, the early colonizers. 

Once the biofilm is established by these early bacteria, the environment starts to change. Over the course of several hours to days, the biofilm matures to the point where it can support other types of bacteria.  These are the anaerobic (oxygen hating) bacteria that can cause gum disease.  These bacteria that cause gum disease are floating in the mouth.  While free floating they cannot damage the gum tissue. Once they can attach to the biofilm they can start to do damage. 

As the biofilm further matures, the bacteria that cause the gum disease grow stronger, and soon becomes the dominant component of the biofilm.  Signs of gum disease begin to appear.  At this point the biofilm is very strong and is not easily disrupted by the body. 

As we review the formation of the biofilm, it becomes obvious that the best way to prevent the gum disease bacteria from growing in the biofilm is to continually disrupt and remove the biofilm.  This keeps the early colonizers the predominant strain in the biofilm, and since these are not pathogenic, we prevent gum disease.

Clinically the best way to disrupt the biofilm within the time frame to discourage growth of pathogenic bacteria is to brush and floss twice each day.  Remember that the biofilm coats the entire tooth, and to break it up you must clean every single part of the tooth.  Done twice each day the pathogenic gum disease causing bacteria are kept floating in the mouth with no place to settle and grow.  This is the single most effective (not to mention cost effective) treatment to allow you to keep your teeth.  Happy brushing!

by Dr. Greg Dilger - May 26, 2011

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