Virtually all gum disease involves plaque produced by bacteria.  Knowing about these plaque bacteria can show us why and how to keep them in check.  (See the Healthy Gums page for an overview of Gum health and gum disease to see why cooperating with nature’s bacteria is better than attempting to kill all the bacteria.)

Plaque is a biofilm that forms on the teeth, especially near where the teeth meet the gums.  On a microscopic level, it’s a transparent mat of bacteria, bacteria by-products,yeasts, viruses, white blood cells, protozoa and mycoplasmas.  It excretes substances that are both adhesive and protective.  It cements itself to the teeth and then hardens to such an extant (into a crystalline calcification called tartar or calculus) that it typically takes a dental hygienist with metal implements to remove it.  It can take as little as 24 hours for the formation of calculus (tartar) to start.

Beneath the hard protection of tartar, bacteria are safe to thrive, and they multiply prolifically in response to our modern sugar-rich diet and the resulting acidic environment.  As the bacteria feed, they release toxins that inflame the gum tissue and actually infect gum cells.  This inflammation is called gingivitis.  Usually there will be no pain sensation at all, making it easy to ignore.  But behind the lips the gums will become redder and start to get puffy, swollen or shiny.  They’ll bleed, especially when a dentist or dental hygienist cleans your teeth, and sometimes even when just brushing, flossing or eating a crisp apple or hard-crusted bread.

The development of disorganized bacteria into organized plaque is a little like when ice forms on an arctic bay as winter approaches.  At first the surface is covered with millions of individual tiny ice crystals, each only about an eighth of an inch across, and they pose no obstacle for even a kayak or canoe.  Then the ice crystals reach out to other crystals, forming and breaking and then reforming fragile bonds, until a continuous sheet of thin ice forms over a section of the bay, called nilas.  It starts off so thin that it’s transparent at first, and can still easily be broken up by a twig.  But if left undisturbed, water molecules that are newly isolated from the air start freezing themselves rapidly to the protected underside of the ice sheet, steadily turning the fragile transparent layer into a rigid barrier called sea ice.  It is so formidable that in a single winter it can become over a meter thick.  Not even a powerful motorboat could make its way through it.  The way to keep a path open for your boat is to keep breaking up the thin ice nilas before it thickens into sea ice.

On a microscopic level, plaque is similar, but its mechanism is driven by chemical attraction rather than by freezing.  An individual free-floating (planktonic) bacterium forms its own hard but tiny mineral shell, but it can’t do any real damage in that form.  The bacterium biochemically attracts the minerals of other bacteria, until chains and then clusters form.  They’re still not too threatening.  The clusters join together to form colonies, and the colonies form an even stronger attraction for each other.  Eventually there’s a continuous, delicate mat of bacteria and other microscopic material covering the gum and tooth margin, called plaque.  The bacteria in plaque thrive on an acid environment, and as they feed and multiply, the by-products of their feeding actually add to the acidity under the mat of plaque.  If left undisturbed, this mat steadily builds a hard protective shell of calcified minerals, called calculus.  Under the hardened calculus, the colonies of bacteria multiply rapidly.

While arctic ice may do no harm to the water underneath, calculus does affect the gum lining that it contacts, causing tiny lesions through which bacteria can invade into the underlying connective tissue.  A large colony of bacteria under the calculus also wields a strong appetite for biominerals, causing inflammation and depleting the surrounding tissue of minerals.  The body attempts to restore the mineral balance by leaching it from nearby “stockpiles”, particularly from the jaw bones that supports the teeth, making the body vulnerable to tooth loss.

The best time to deal with plaque bacteria is when they are fragile and vulnerable.  We can’t be without the bacteria; they’re part of the normal flora involved in our digestive process.  We can’t stop them from always joining up with each other to form plaque; they flourish in the sugary and acidic environment of our mouth.  But what we can do is break up and loosen the plaque before it crystallizes into hard, thick calculus.  This can be done by the mechanical action of brushing, flossing, interdental cleaning, and pocket irrigation.  When these mechanical actions also employ a suitable cleansing agent that neutralizes acidity as well as more thoroughly cleansing the teeth and gums, the effect is enhanced.

Since the gums are located between the underlying tooth-supporting tissues and the bacteria-rich mouth (see Healthy Gums page), they are capable of dealing with the occasional opportunistic infection by bacteria that’s bound to happen if the gum surface (epithelium) gets injured, gets irritated, or if the bacteria get too populous.  The gums are well designed for immune system activity.  The gum connective tissue beneath the gum lining funnels specialized cells to the infection site that devour the invading microorganisms (phagocytes, mostly in the gum lining) or that kill them (lymphocyte white blood cells, mostly in the gum’s deeper connective tissue).  As other live cells react to the toxins of the bacteria and to the microscopic battle taking place between immune system cells and bacteria, and as dead cells accumulate, the gum tissue at the infection site swells up.  When the source of the irritation (like calculus) is removed and the bacteria population is kept under control, our immune system can handle the remaining invaders and all we experience is a temporary and reversible flare up of gingivitis.  The situation starts getting serious if there are repeated bouts of gingivitis or if the gingivitis is allowed to continue unchecked.

With continual exposure to tartar and to the toxins secreted by the plaque bacteria, gum tissue starts to recede.  The small overlap between the gums and a tooth deepens to form a gum pocket, a relatively deep hollow where there’s detached gum tissue on one side and some bare tooth on the other.  Anaerobic bacteria (that cannot live in the presence of air) can thrive in gum pockets, producing their own addition of toxic byproducts to those of normal bacteria.  Inflamed surface (epithelial) gum tissue in the gum pocket also starts to develop additional openings where the bacteria can invade the gums, causing even deeper inflammation, not just to the surface of the gums but also to the underlying connective tissue (periodontal ligaments) that help support and bond the teeth to the bone.  As the pockets penetrate deeper along the tooth root, as the gums recede and as inflammation moves into deeper tissue, the tooth-supporting bone itself starts to recede.  There is evidence for cells dying off both from the toxins of the bacteria and from the immune system’s attempt to isolate chronic infection by “amputating” inflamed cells.  The infection does not necessarily progress evenly from the outside in.  Cells in the tooth-supporting bone and ligaments can start to die off faster than they can be replaced while the softer connective tissue of the gums is still fighting to stay viable.  (To see more detail on the mechanism of how bone cells die off and are replaced, click on Menopause and Gum Disease.)  This dying off and recession of tissue away from the tooth is called periodontal disease.  Eventually it leads to loose teeth and the loss of teeth.

Unfortunately there’s more at stake than our cosmetic appearance, than our breath’s scent or even than retaining our teeth.  Unhealthy gums have been associated with serious diseases such as heart disease, arterial plaque, stroke, diabetes-complications and even pancreatic cancer.

As gum disease takes hold and progresses, it gets more difficult to regain gum health.  But before the bacteria become organized, it’s not hard to deal with, before calculus (tartar) forms and before gingivitis, gum pockets and periodontal disease show up.  Prior to the formation of calculus, plaque is a relatively soft mat of microscopic matter.  Prior to the formation of the plaque mat, the bacteria are in relatively benign chains, and before that, the bacteria are pretty vulnerable as disorganized individual cells or spores.

While a mouth must necessarily contain bacteria, very close to the mouth is another body area, the brain, which by necessity must be totally free of bacteria in order to be healthy.  To help contain the bacteria, the soft and bony tissues of the mouth have developed intensely active immune system capabilities.  Multiple pathways exist to rush immune cells to the site of any mouth infection; inflammation can work feverishly to “amputate” chronically infected cells if necessary.  Even an infection that’s left unchecked for a long duration will have a hard time spilling over into the brain-even if it means the body has to sacrifice tooth-supporting cells to contain the damage to the mouth area.  Obviously, it’s best not to let the plaque bacteria get to this stage of having the upper hand.

To keep the plaque bacteria in check and to fend off gum disease, we need to cooperate with our body’s natural ability to heal itself and to stay in balance.  First accumulations of hardened calculus (tartar) should be removed by a dentist or dental hygienist.  Then while the calculus is gone and the plaque bacteria are in disarray, we must keep disrupting their organization before they can take harmful forms.  And we should keep supporting the health of our gum tissue to better resist bacterial infection.

Cells grow and are replaced in the mouth much faster than other body parts.  The mouth’s intensely active immune system and healing capability means it’s almost never too late to adopt practices to achieve gums, teeth, alveolar bone and periodontal ligaments that are free of the chronic infection.  And when the body isn’t preoccupied fending off chronic infection, it can grow healthy cells.

If you’re serious about fighting gum disease, read what it takes to have healthy gums and teeth.