Dental Plaque Tooth Decay and Gum Disease

Read about it in the Journal of The Royal Society of Medicine
There is a battle being fought for the ecological space in your mouth, a battle which is ongoing every day.  There are many microscopic organisms that thrive in moist warm places where there is plenty of “food” available.  The mouth is such a place. It is moist all the time, it is warm at blood heat, and there is an abundant supply of various foodstuffs left over from our diet, and importantly from the desquamated cells of the constantly shed mucosal lining of the oral cavity.

We could give the members of the army of occupiers that colonize our mouths names, like “Streptococcus mutans” and while it might be erudite it can possibly complicate unduly the basic message being communicated here.  It is impossible to eradicate bacteria from our mouths. Our bodies are covered with bacteria, they reside in every crevice, every nook, and cranny, every entrance to the body’s chambers.  They all have specific types of bacteria that thrive in each location, varying complements that balance each other and are especially well suited to each area sometimes supporting their mutual survival in a synergistic way.  The presence of one type of bacteria may enhance the opportunity for survival of another, and herein lies a particularly interesting conundrum.  While we might not want a particular bacteria in our body cavities, their presence actually prevents other organisms that would be much more harmful to us from colonizing the space in their stead.  A brief example of this can be drawn from the number of times we hear that so and so does not want to take antibiotics again, because every time they take them, they get a yeast infection.  This is a simple demonstration that if we disturb the naturally occurring bacterial complement by taking a medication, we run the risk of potentiating an opportunistic infection which was being kept at bay by the commensal bacteria that form the ground guard of that space.

Microscopic Organisms and Plaque

The bottom line then is that we need commensal colonizing organisms to prevent more hostile invasion and occupation by other more virulent and damaging life forms.  These might not be only bacterial, they can be yeasts and fungi and viruses.

So with this in mind, what is the problem for dentists and why would I bother to write this post for my patients and friends.  Basic biology teaches us that all living organisms have seven vital characteristics, they respond to stimulus, they grow and repair, they pass genetic material from one generation to another, they metabolize nutrient materials upon which the surviving, they move, they respire, and they excrete waste materials that they no longer need, these are the by-products of their life cycle.  It is this last vital characteristic, the excretion, that causes all the trouble for you and the dentists the justification for his job.

The bacteria in your mouth anchor themselves into position in the crevices between the teeth and gums and between the papillae on the rough tongue surface by secreting a mucopolysaccharide gel.  This gel, which is sticky, and binds all the bacteria together in a colony or plaque, is waterproof and requires mechanical stimulus to penetrate it and disturb it.  Into this plaque, the bacteria excrete all the waste products that would poison their cells.  This toxic waste is acidic and irritant to our tissues.  These physical properties are what damages the tissues in our mouths and are the primary reason why we need dentists.

Tooth decay and Dental Plaque

The acidic nature of the excreted waste from the bacterial life cycle is strong enough to dissolve out the minerals, the calcium salts, from which the crystals of the tooth enamel and dentine are composed.  The pH, the percentage of hydrogen ion, does not have to be very high to have a value of 5.5, but at this concentration, the minerals are literally dissolved out of the crystals.

The irritant characteristic of bacterial waste, produces an inflammatory response in our gums and makes them swell, and causes the blood vessels to dilate in an attempt to bring more protective body fluids to the area. The blood vessels bleed easily, and a critical signal is given which tells our bodies to start an inflammatory process.  This swelling of our gums makes the normally tight cuff of gingiva around each tooth loose and the pocket deeper.  There are two effects that then produce the changes we call gum disease or periodontal disease.  I would like to discuss them now before talking about plaque control.

The first important factor in protecting the teeth is that each tooth is surrounded by a tight cuff of gum tissue called the gingiva.  The depth of the cuff is usually about one to three millimeters deep, and each cuff is washed out by a flow of crevicular fluid which weeps out from the cells at the bottom of the cuff every time your heart beats.  At the height of each pulse of blood pressure that passes in a wave throughout our bodies, fluid flows into the cuff, and this fluid flushes out the cuff, preventing bacteria from entering, and washing out any excretory products.  When the gums are inflamed and swollen the pocket is deepened and becomes loose and wider. Then the flow of fluid is inadequate to flush the bacteria out.  This results in toxic materials accumulating in the cuff, and this damages the connection of the gum to the tooth and recession occurs.  The gums recede.

Our teeth are supported by bone in our jaws and held in place by a fine sling of white fibers called the periodontal ligament.  The bone, like all bone, is being remodeled continuously.  In fact, bone is completely remodeled in health about every one hundred and twenty days.  That is why our bones can be reset and mend after breaks.  However, in the presence of an inflammatory response the messages telling the cells to remodel and lay down new bone are interrupted, and while old bone is removed, new bone deposition is delayed.  The net effect is that the height of the bone supporting the teeth gradually recedes.  This is the factor that causes our teeth to become loose and eventually if left untreated, lost.

One other critical factor is that bacteria have a very short life cycle.  In twenty minutes they are formed by cell division, they metabolize and grow large enough to divide and double in number.  Threefold in an hour, thirtyfold in ten.

So now we see that we cannot eliminate dental plaque, nor would we want to.  We need the bacteria in our mouths to keep other organisms at bay. It is imperative that we control the plaque colony by diminishing its thickness and by disturbing it to the point where our saliva can neutralize the toxic and acid contents of the plaque colony.  That is what tooth brushing and flossing are all about.  They are designed to break up the colony and let saliva do its work.

A word about Saliva the miracle liquid.  Saliva is a supersaturated solution of calcium salts produced by special glands which allow us to save our teeth.  Saliva not only contains mucus that makes food slippery so that we can swallow it, and water so that our food can be dissolved and tasted.  It also contains immune- proteins that help against infection, and it is alkaline most of the time.  This alkalinity is what neutralizes the acidity of the bacterial plaque and stops the teeth from being dissolved.  The special ingredient calcium is what all the difference.   Some of us have bitten into a lemon and noted the rough feeling of the teeth immediately afterward.  What is the explanation for it?  Well, it is the result of citric acid that has etched into the tooth and produced microscopic indentations that make the tooth rough.  But two hours later the teeth will feel back to normal.  That is the repair process resulting from the saliva reconstituting the outer layer of the tooth. Saliva literally re-crystalizes the enamel on our teeth. We are wonderfully made, and this facet of human biology, the way our teeth are prevented from dissolving away is amazing.

All we have to do to save our teeth and prevent them from needing complicated treatment and repair is to brush and floss daily and see a dentist