It is rare that a scientific paper blows me away, but a recent paper in the journal General Dentistry (2011 Vol. 59, #5, pp 367-368) by Dr. Ken Southward, entitled “The Systemic Theory of Dental Caries” did just that.  (Remember, caries is the scientific name for tooth decay.)  Right click on the link to read a copy.

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It explains in detail some of the body’s defense mechanisms for preventing tooth decay and how it is under hormonal control.  The main irritant causing the damage is acid, produced by bacteria, but the body can fight back!  Teeth are hollow inside and there is a pressure gradient through the tooth that causes fluid to flow from the center, through the dentin and enamel rods and “wash” the tooth clean. This directed pressure gradient is called centrifugal flow.  This nourishing and protective fluid flow is under the control of a hormone made in the parotid gland called parotid hormone.  Who knew that the parotid gland had an endocrine function?  I didn’t.  The release of this hormone is part of a feedback system that is controlled at the level of the hypothalamus.  Guess what blocks this feedback loop, leading to a stoppage or even reversal of the flow?  That’s right, sugar!  Acting at the level of the hypothalamus.  This blockage is the initiating mechanism of tooth decay.

In my lecture, I used to state that all disease in the body is mediated by the inflammatory response except one: tooth decay.  I can no longer say that.  This paper ties tooth decay directly to the inflammatory response.  This theory is not new but the evidence proving it is.  In the 1940’s, Dr. Schatz proposed what is now called the proteolysis chelation theory.  Unfortunately, the theory fell out of favor and the theory that carried the day was the Acid Theory, by Dr. Miller.  This is not a big deal for one reason, and yet a very big deal for another.

On one hand, acid is still the main irritant and this does not change the current treatments.  So this is not that dramatic a change.  On the other hand, we have been treating tooth decay with an INCOMPLETE THEORY for the last 70 years!  A correct and complete theory will allow us to not only better understand the process but to target correct treatments to solve the problem, not to mention better ways to institute preventive measures.

The next mistake in the comedy of errors is that Crest toothpaste with fluoride became the first toothpaste to receive the ADA seal of approval.  Proctor and Gamble was able to use this advantage to market Crest and dominate the toothpaste market.  Its competitors tried and eventually received the same certification.  Anyone who is familiar with the American marketplace knows what happens when marketers receive a “seal of approval” from a respected organization.  A paradigm is established and it becomes the “conventional wisdom.”  Once such a paradigm is established it becomes very hard, if not impossible, to change.  Anyone who challenges it is attacked.

Dr Southward states it best:

“This endorsement was granted with a limited understanding of the caries process based on the Acid Theory.  Acid is now understood to be only an initiator of enamel erosion and stimulator of an uncontrolled inflammatory response in the dentin.”

I had always suspected that acid was not the entire story but had no evidence.  In twenty years of practicing dentistry I have seen a number of patients who exhibit signs of past or current bulimia. Bulimia causes an erosion of the enamel of the tooth and since the body cannot replace it, once it is gone, it is gone for good.  If you have ever seen a rocky shoreline at low tide where the rocks are washed away and undermined by the action of the tides, that is what bulimia does to teeth.  It is very distinct.  Under the enamel layer there is another layer called dentin.  The dentin has a much lower mineral content than the enamel but a much higher collagen content.  Collagen is impervious to the actions of acid.  In bulimia patients, the enamel “washes” away but the collagen is much more resistant to the acid and the dentin stands.  I always wondered why the dentin did not vanish as well. Now I understand that it is the inflammatory reaction that takes out the collagen as the acids take the mineral content away.  This is caries.

As it is becoming understood that the basis of tooth decay is inflammation, it makes sense that anti-oxidants will have a protective effect on the human dentition.   They act locally as an electron donor, neutralizing the reactive oxygen species (ROS) or free radicals that lead to the inflammation.  No inflammation = no loss of dentin = no decay. Foods that contain a high level of anti-oxidants include green tea, lemons, and dark chocolate.  One of the most powerful anti-oxidants is oil of clove, or eugenol.  Dentistry has been using this essential oil for hundreds of years.  Its anti-oxidative power is so high it can relieve dental pain.  This also explains how in the early 20^th century, when Dr. Weston Price traveled the world examining cultures, where he found cultures eating traditional diets low in sugars and high in anti-oxidants, dental problems were few.

In the low carbohydrate community fluoride is considered controversial.  In the dental community it is considered standard operating procedure.  As long as people continue to eat a standard American diet, I believe that there will be a need for fluoride.  Anyone who knows me knows that I often express my frustration for educated people who refuse to examine new paradigms.  Taking fluoride away from dentists will make most of their heads explode. I am not ready to give up on fluoride, I am however, ready to give up on the standard American diet.  Today I believe it is a patient’s choice whether or not to have fluoride applied to their own or their children’s teeth.  Remodel the diet and along with decay, the need for fluoride will disappear.  That will require changing the paradigm.  Who’s with me?