• 6/3/2007
  • Sacremento, CA
  • Dorsey Griffith
  • Sacramento Bee (www.sacbee.com)

A developing health science aims to prevent disease by focusing on mouth bacteria

You might be surprised to learn that the microscopic bugs around your teeth that cause gum disease may also contribute to tongue cancer, medical researchers recently reported.

Such a link would not, however, shock the legions of oral health professionals paid to clean teeth and gums, restore teeth and scare patients into flossing daily.

Mounting evidence linking gum disease and other physical ailments is bucking the long-held notion that the mouth and body should be treated as separate entities by different kinds of doctors.

“For a long time, dentists really saw themselves as drilling and filling and didn’t look at the ecological causes of oral health and how important it is in our total well-being,” said Jennifer Holtzman, associate professor at the University of Southern California School of Dentistry. “Dentists are now finding themselves in the position of being able to prevent tooth decay and really take a lead role in helping people manage their own health.”

Scientists already have associated periodontal disease with heart disease, diabetes, respiratory illness and several pregnancy-related problems including infertility, preeclampsia, and premature and low-birth weight babies.

The science is young and inconclusive, however. What’s not yet known is whether diseased gums actually cause or contribute to other illnesses, and whether prevention of periodontal disease — through regular exams, cleaning and good oral hygiene — could actually prevent or lessen the effects of other health problems.

Still, these associations are convincing enough to spur more aggressive general health screenings in dental offices and to prompt insurance companies to offer enhanced benefits for employees at higher risk for periodontal disease complications.

“This area is very exciting, leading to a growing awareness of the importance of good oral health, not just for appearance’s sake, but for longevity and life,” said Jeff Album, director of public and government affairs at Delta Dental, an insurance company with an enhanced periodontal benefit for pregnant members.

That said, Album noted, “We don’t have a causal link established between periodontal disease and any of these other conditions. It’s plausible that other risk factors will ultimately be shown to be the cause.”

What isn’t disputed is that the mouth is loaded with microorganisms, and is home to hundreds of species of bacteria that can be both useful – as in digestion – and destructive, as in gum disease.

These bugs collect to form sticky plaque, also called “biofilm,” which nestles between teeth and builds up along the gum line. Ignored, it can cause gingivitis (inflammation of the gums), and progress to periodontitis, an infection that causes disintegration of the bone and tissue that support teeth.

As the theory goes, untreated periodontitis can wreak havoc on other body systems, either through the spread of bad bacteria from the mouth to the rest of the body or because of the inflammation caused by that bacteria.

The inflammation occurs when bacteria give off toxins that stimulate the immune system to produce cytokines. Cytokines in turn induce inflammation.

Mine Tezal, a dentist and researcher at the State University of New York, believes either one of those mechanisms may be at work in tongue cancer development, and possibly other types of oral cancer, as well.

She notes that bacteria or viruses have been implicated in other malignancies, including cancers of the colon, cervix, lung and stomach.

Working with researchers at the Roswell Park Cancer Institute in Buffalo, N.Y., Tezal compared 51 white men with tongue cancer to 54 white men without tongue cancer. Mouth X-rays assessed each patient’s periodontitis by calculating bone loss in tooth cavities.

The researchers found that bone loss was markedly higher in the men with cancer. Even after adjusting for age, smoking history and number of teeth, they found a more than fivefold increase in the risk of tongue cancer in those with bone loss.

While Tezal can’t explain the possible association, she hypothesizes that the microorganisms or their products can cause mutations in genes leading to cancer or that they stimulate cytokine production, creating an environment for tumor development.

Tezal points out that her research, published in May in the Archives of Otolaryngology-Head & Neck Surgery, needs to be followed by larger studies before any solid conclusions are drawn.

Regardless of the state of the science, dentists today routinely look for evidence of other diseases before dealing with a patient’s periodontal problems.

“If they are diabetic, we want to know what their blood sugar readings are,” said Debra Finney, a periodontist in Folsom. “If their diabetes is out of control, their mouth will be out of control.”

The reverse also may be true. A Danish study conducted in rats found that having periodontal disease can contribute to the progression of Type 2 diabetes in susceptible patients.

Another recent study, this one adding to mounting evidence linking heart disease with gum disease, was published in the New England Journal of Medicine in March. It found that when severe gum disease is aggressively treated, there is eventual improvement in the function of blood vessel walls – at least in the brachial artery along the arm. Problems in coronary artery function can signal the onset of heart and vascular disease.

“That (finding) could be a major breakthrough in the management of (clogged arteries),” said Preston D. Miller Jr., president of the American Academy of Periodontology. “The problem is that we don’t know if the same thing occurs in the coronary artery. Until someone can show that … we cannot make that correlation.”

Carmichael dentist Laurie Hanschu, who closely follows the emerging science, said she is fascinated but wary about claims of links yet to be firmly established.

Still, she said, treating periodontal disease is likely beneficial to a patient’s overall health.

That’s why each of her new patients undergoes a thorough medical evaluation, including a lengthy medical questionnaire.

Tanya Boyd of Granite Bay sought out Hanschu for her first dental appointment in five years – something she avoided after a terrifying experience with a hygienist she said had a car mechanic’s touch.

For her first visit, she was scheduled for teeth cleaning and whitening. She left without either.

Instead, Boyd got an hourlong exam that included X-rays, photos, cancer screening, jaw joint checks and probing for tartar below the gum line, exposed roots and inflammation.

“I’ve never had an exam like that,” Boyd said with both surprise and relief when it was over.

Boyd also left with four more one-hour appointments for in-depth periodontal cleaning called root planing and scaling, in addition to the whitening.

The insurance industry also is paying close attention to the scientific findings, and generating some of its own. Insurance giant Aetna, in collaboration with Columbia University College of Dental Medicine, found that patients with heart or vascular disease or diabetes lowered their overall medical costs when they got early and regular dental care.

The company now targets members it considers at risk, encouraging them to take advantage of their dental benefits, which include enhanced services such as additional cleanings.

“We feel confident that the medical costs and long-term dental costs will eventually be lower,” said MaryLee Conicella, national director of clinical operations for Aetna Dental.