What can I do about my canker sores

If you get canker sores, you are one of the "lucky" few.  Only about 1 out of 10 people develops canker sores.  The real name for this condition is aphthous ulcers.  Canker sores are actually a mild auto-immune reaction.  First, I should explain how a canker sore comes about.

There are several stages to the life cycle of a canker sore.  Canker sores are thought to be caused by a physical injury to the soft tissue.  On suseptible people, instead of the body immediately acting to repair the damage, certain elements of the immune system declare the injured area as a foreign body.  After injury, the immune system attempts to destroy the "foreign body" and kills cells in the area.  When the sore gets large enough (usually about 3-5 millimeters in diameter), then another part of the immune system recoginzes that a mistake has been made by the immune system, stops killing cells in the area, and healing begins.  By the time healing begins, bacteria from the mouth have begun to invade the area and also has to be cleared out.  Little can be done with today's technology to stop the immune system's foreign body type reaction in the area.  However, either or both of the other stages of the sequence (physical injury and bacterial invasion) can be shortened or eliminated.

Physical injury to the soft tissue can come in several ways.  Of course, there is the injury that can come from eating sharp foods like corn chips, or a biting injury, or injury to the soft tissue from a blow to the mouth, or even a burn.  These types of injuries are common.  One type of injury you may not have considered is the injury that results from the acid in plaque.  If plaque is not brushed or flossed away a couple of times each day, the soft tissue that comes in contact with the plaque is continually bathed in mild acid.  In time, this acid can easily cause injury.  Sometimes I see patients who have developed canker sores along the edge of the tongue (lateral border).  The most obvious cause of these sores is plaque buildup on the inside surface of the lower teeth.  For some people, acidic foods like tomatoes can cause canker sores.  If you know you get canker sores after eating certain foods, it's best to either avoid eating those foods or brush after eating them.  Even a vigorous swish with water after eating the offending food should help to avoid canker sores.  If you don't brush much and you get a lot of canker sores, try brushing every day.  As for the jabbing, cutting, or burn injuries, usually we have already attempted to avoid the behaviour that resulted in injury.

The autoimmune portion of the life cycle of a canker sore usually lasts about 4-5 days while the bacterial colonization portion usually lasts a week or more.  Little can be done to stop the autoimmune portion of the process with today’s technology, but the bacterial portion can be greatly shortened or even eliminated.  There are several products that kill enough bacteria to nearly eliminate the bacterial stage of canker sores.  All are prescription products except one--Listerine.  For Listerine to work, it must be used full strength, and swished for 30 seconds several times every day.  A very extensive and impressive study from a few years ago which compared the bacteria-killing ability of more than a dozen of the most common over the counter (non-prescription) mouthwashes found Listerine to be by far the best.  The same study also found that all of the bacteria-killing capability of Listerine comes in the first 30 seconds.  Because of this, there is no need for a longer rinse time.  All three flavours have the same active ingredients and work the same.  If you are like me, you will need to swish with cool water after swishing with Listerine.


If you are one of the “lucky” few who are plagued with canker sores, ask your dentist for personalized advice for your case.      


