Taking a bite out of gum disease Researchers teach old drugs new tricks for teeth.

February 02, 1993|By Boston Globe

Using familiar old drugs in surprising new ways, researchers are making inroads against one of humankind's most ancient and universal diseases -- periodontitis, or inflammation of the supporting structures of the teeth.

For instance, some scientists are exploiting a newly discovered property of the old standby antibiotic tetracycline -- a property that has nothing to do with the drug's germ-killing ability -- to block the tissue destruction that causes teeth to loosen and fall out.

Others are using antibiotics in the traditional way to kill bacteria. But to deliver the drug they're impregnating fibers with it and stuffing the fibers into patients' gums for controlled-release doses. Another group of scientists is putting common arthritis drugs similar to ibuprofen, the active ingredient in Motrin or Advil, into experimental mouthwashes and toothpastes.

The advances, all of which are in human trials, may also have important implications for other major human ailments, such as rheumatoid arthritis, osteoporosis and even cancer, researchers say.

But the recent innovations in periodontal disease are important in their own right.

Nearly four out of five adults suffer from some degree of periodontal disease, according to federal government surveys, and about one in six people between the ages of 60 and 64 has advanced periodontal disease. The number of affected people can only grow, researchers say, as dentists' success in combating tooth decay leaves more teeth vulnerable to periodontal disease.

Periodontitis starts with painless bacterial infection of the gums that is often undetectable to the sufferer. The infection triggers immune reactions that, researchers now know, results in destruction of the connective tissue that suspends teeth in their sockets. The process can end with erosion of the underlying bone and supporting structures so severe that teeth simply fall out. To save and replace teeth, periodontitis sufferers must spend thousands of dollars and endure considerable discomfort.

Conventional treatment relies on mechanical interventions such as probing of gums to diagnose periodontitis and scaling or root-planing of teeth to remove bacteria-laden deposits. But that often comes too late to prevent much of the bone loss that loosens affected teeth.

Scientists have known for decades that periodontitis is a bacterial disease, at least at its inception. And since the 1960s they have pinned down the half-dozen or so bacteria that are largely responsible, out of the 300 or more species that inhabit the human mouth.

The emphasis on the role of bacteria has led to the widespread use of antibiotics as an adjunct to the scraping of calcified bacterial deposits called tartar from the teeth. But antibiotics have their risks, such as the rapid development of antibiotic-resistant bacteria.

This problem has led Dr. J. Max Goodson of the Forsyth Dental Center in Boston to devise a method to deliver antibiotics directly to the site of inflammation. Synthetic fibers resembling dental floss are impregnated with tetracycline and wrapped around affected teeth, and the antibiotic slowly leaks out to affected tissues.

In a multicenter study of 107 patients published in 1991, Dr. Goodson and his colleagues tested the tetracycline fiber therapy against conventional scraping alone, fibers not containing antibiotic and mere improved home dental hygiene. Patients who got the antibiotic-impregnated fiber did significantly better on a number of measures, such as decreased depth of periodontal "pockets" -- abnormal spaces between gum and tooth that are a hallmark of the disease -- and lessened bleeding.

The California-based Alza Corp. is awaiting action by the U.S. Food and Drug Administration on its 4-year-old application for tetracycline fiber therapy as a new 10-day treatment for periodontitis, according to spokeswoman Laura Mills.

Meanwhile, other researchers have shifted their focus from the bacteria themselves to the body's damaging reactions to periodontal infection. Scientists call this the "host response," the host being the patient and the guest the bacteria.

Considerable evidence has accumulated in the past decade supporting "the belief that the host response causes the actual destruction" or periodontitis, reports Dr. Ray C. Williams of the Harvard School of Dental Medicine. It's as if an irate host trashed his own house in a vain effort to get rid of unwelcome guests. Armed with this insight, scientists are focusing on methods to calm the host.

One way is to employ anti-inflammatory drugs already widely used to damp down chronic inflammatory diseases such as rheumatoid arthritis. These drugs -- called NSAIDs for nonsteroidal anti-inflammatory drugs -- block prostaglandins, potent inflammation-inducing chemicals that flock to the site of bacterial infections.

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