Of all the things that can go wrong with the human body, gum disease must rank among the least glamorous. One of its symptoms, after all, is bad breath.
But this prosaic ailment is beginning to get some respect.
Now that fluoride has quelled cavities, gum disease (formally called periodontal disease) is dentistry's biggest challenge. Researchers are attacking it with an armory of ingenious and powerful tools that range from drug-embedded string to nuclear isotopes. Even the introduction of competing bacteria--a kind of oral battle of the bugs--could someday be part of a trip to the dentist.
Why bother? Certainly not because it hurts. Periodontal disease is one of the most sneaky, insidious diseases imaginable.
Most Have Disease
Three-fourths of all adults have the disease, and they don't feel a thing until the damage is already done. However, the consequences are obvious enough. Periodontal disease makes people's teeth fall out. It is responsible for roughly 70% of all lost teeth. Because of it, about a third of all Americans over age 45 don't have a tooth in their heads.
With routine care--diligent brushing, flossing and professional cleaning--periodontal disease often can be avoided. That it still happens, and happens so often, reveals perhaps the dental profession's foremost task in fighting the disease: public education.
"We have a colossal problem of trying to communicate to the public that this is a disease that you cannot diagnose on your own until it's too late," says Dr. Harald Loe, director of the National Institute of Dental Research. "There has to be an awareness that they need to be checked routinely for the early stages of periodontal disease, when the treatment is relatively simple and we can save the teeth for a lifetime."
A Bacterial Infection
One enduring myth is that people lose their teeth as a natural and unavoidable part of growing old. They don't. Periodontal disease is a bacterial infection.
Even its common name, gum disease, is misleading. The first stage is indeed a gum infection called gingivitis. But the real trouble begins when the infection progresses to ligaments and bone that surround the teeth--a condition known as periodontitis. It literally erodes the bone until there is nothing left to hold up the teeth and they fall out.
Combatting the disease, once it gets going, is fraught with problems. One of the most troublesome is figuring out whether a patient actually has it.
Periodontal disease causes pockets to form around the teeth. These fill up with bacteria and perpetuate the destruction. Dentists can probe the gaps with instruments and tell whether someone has lost bone. But the disease flares up and dies down. Probing won't reveal whether someone has active disease.
Dentists Take X-ray
To learn this, dentists take an X-ray, wait a few months, and then take another one. If bone has evaporated between the two pictures, then they have a crude idea of what is going on inside their patient's mouth.
"It's like cardiology in the old days, when you just depended on your stethoscope," said Dr. Irwin D. Mandel, director of Columbia's Center for Clinical Research in Dentistry. "We want something that's the equivalent of the electrocardiogram."
Finding better ways to diagnose periodontal disease is one of the hottest areas of dental research. One approach, conceived by Dean Paul Goldhaber of Harvard Dental School, is nuclear medicine--or what, in this case, could be called nuclear dentistry.
The technique has been a mainstay of medical sleuthing for many years. Technicians chemically bond a radioactive isotope to material that will be selectively absorbed by some interesting part of the body, such as a bone fracture, damaged heart tissue or a tumor. If the thing they are looking for--such as a cancer--absorbs the material, it will show up as a hot spot on a scan.
A Quick Reading
At Harvard, Drs. Marjorie K. Jeffcoat and Ray C. Williams are adapting nuclear medicine to show areas around the teeth where bone is actively being lost.
Such a diagnostic tool would be useful to dental researchers, because it would give them a quick reading of whether an experimental treatment is working. But it also could assist the routine care of patients with advanced cases of periodontal disease.
For instance, it would be nice to know the health status of a single tooth if a dentist is planning to use it to anchor thousands of dollars worth of bridge work. A scan also could guide them in deciding when patients need antibiotics to wipe out their dental germs.
The apparatus seems to work well on lab animals, and the researchers hope to test its safety and effectiveness soon on people.
"It may greatly aid research efforts, and ultimately it might alter treatment of special cases," Williams said.
Identifying the Bacteria
Another goal is identifying the bacteria that do the damage. Some experts believe that periodontal disease is actually a cluster of ailments, each with its own microscopic culprits.
"Until you establish the causes of each of the diseases, you really are nowhere in terms of diagnosis or precise treatment planning," said Dr. Sig Socransky of the Forsyth Dental Center in Boston. "Step No. 1, in my mind, has to be to find the causative agents."
That the mouth is full of little living things has been known ever since Anton Van Leeuwenhoek scraped some white stuff off a tooth and peeked at it under his invention, the microscope.
"There are more animals living in the uncleaned matter in one's mouth than there are men in a whole kingdom," he noted 400 years ago.
Leeuwenhoek wasn't exaggerating. One tooth can be home to 150 million microbes. The white stuff he looked at was plaque, a film of bacteria.
But it was not until about 30 years ago that scientists definitely connected bacteria with periodontal disease. Now it is clear that germs are involved in destroying bone, but so too, ironically, are the body's own defenses against these bacteria.
Among other things, the bacteria make proteins called enzymes that speed up chemical reactions. One of the enzymes is collagenase, which breaks down collagen, an important building material in the body.
The body dispatches specialized white blood cells to fight the bacteria. But in the course of their duties, the cells also manufacture damaging enzymes, including collagenase. Another of the body's reactions is to produce prostaglandins and other chemicals that inflame the gums and erode the bone around the teeth.
Researchers at several institutions are developing tests that will reveal the presence of these enzymes and, they presume, active periodontal disease.
"Monitoring periodontal disease in the home is not an unlikely possibility in the future," Mandel said, "but I think a more immediate possibility is to expand the use of diagnostic techniques in the dental office."
Scientists are also interested in several approaches to preventing periodontal disease or stopping it once it starts.
One idea is the use of antiseptic mouthwashes. A substance called chlorhexidine has been available in Europe for about 15 years.
Not Approved in U.S.
This and similar antiseptics are being investigated in the United States, and although none has been approved for routine use, Loe said, "I cannot conceive of the possibility that the American public is not going to enjoy some of the technology that is available in other parts of the world."
One way of wiping out periodontal bacteria, at least temporarily, is with antibiotics, such as tetracycline. Laboratories also are examining the potential usefulness of a variety of other antibiotics, both those currently on the market and new ones being developed.
Many doctors, however, are reluctant to give people antibiotic pills for long periods of time. The drug kills all kinds of germs, not just those that are responsible for dental disease, and this hastens the growth of bacteria that are resistant to the drug.
At Forsyth, Dr. Max Goodson has developed a piece of plastic string that is embedded with tetracycline. The string is shoved under the patient's gums. There the antibiotic slowly dissolves, killing the dental germs but not journeying through the patient's body as ordinary pills do.
Another Forsyth researcher, Dr. Jeffrey D. Hillman, is toying with the "warring-bugs" approach. Ordinarily, all kinds of bacteria coexist in the mouth, but only some of them cause dental disease. There are, in short, good germs and bad germs, and they form a complex society, an ecosystem, where one variety keeps another from multiplying out of control.
In some people, it seems, the bad germs have gotten the upper hand. Hillman plans to implant two missing strains of good streptococcus bacteria, called sanguis and uberis, in these people's mouths.
"The idea is that when an individual presents us with that sort of microbiological picture--lots of bad guys and no good guys--we hope to implant some good guys and re-establish a normal ecosystem in their gums and prevent progression of the disease," Hillman says.
Still another drug approach is being tested at Harvard. Williams and his colleagues are giving patients flurbiprofen, a powerful anti-inflammatory drug that blocks the body's production of prostaglandins.
Ignoring the Disease
Even if some of the treatments turn out to be useful, they won't make much difference unless dentists pay more attention to periodontal disease. One federal survey found that dentists devote only about 5% of their time to the disease.
A report three years ago by the American Assn. of Public Health Dentists accused the profession of ignoring the disease and said: "The dental generalist has become, by default, part of the problem rather than part of the solution of periodontal disease."
However, Williams said this situation is changing. "Dentists are making a phenomenal push toward making sure their patients receive proper periodontal treatment," he said. "I see a real growth coming in the education of dentists about periodontal disease."