A Mouthful of Evidence
What's the link between periodontal disease and low-weight babies?
Pre-term and low-weight babies enter a different world from normal newborns. "Preemies" begin their lives in a world populated with incubators to keep them warm, ventilators to help them breathe. Often, the infants are subjected to phototherapy, a special light that bathes their body to metabolize a reddish-yellow pigment that can cause jaundice.
The vessels of preemies are so fragile that brain-bleeding is possible, and infection is a constant risk. These are only some of the dangers. And working to avert them has a price tag: when a premature baby is admitted to a neonatal intensive care unit, it costs an average of $30,000 more than if the baby were healthy.
Nationally, an average of 12 percent of births are pre-term, and 8 percent of infants born have a low birth weight. In Kentucky, more than 4,000 infants are premature each year. Prematuritywhich has increased by 27 percent in the United States since 1981is the leading cause of death in this country within the first month of life.
Why some women cannot carry to full-term is not always clear.
Trying to connect cause & effect
Doctors will tell you that the cause of low-weight births may be biological, chemical, genetic, or a combination of factors. At the University of Kentucky, researcher Jeffrey Ebersole, associate dean for research in the College of Dentistry, believes there may be another cause: periodontal disease.
In previous studies, researchers found that expectant mothers with periodontal disease may have a three- to seven-times greater risk of giving birth to premature and low-weight babies, and these findings made Ebersole want to investigate this possible link.
While important, findings from these studies are only "associational," he says, and do not prove cause and effect. "There are little data distinguishing whether the two problems are linked by causation or due to the same underlying risk factors," says Ebersole, who also serves as director of UK's Center for Oral Health Research. Now, backed by a five-year, $3.3 million grant from the National Institutes of Health, he is working to find a link between periodontal disease and low-weight babies. "Our goal is simple: we want to help make it possible for mothers to give birth to healthy, normal babies."
In trying to establish this cause/effect connection, Ebersole first needs to understand the cause of periodontal disease, an inflammatory condition of the gums and bone supporting the teeth that can ultimately lead to an erosion of the gums and the loss of teeth, so he's starting with bacteria that live in the mouth.
As far as bacteria are concerned, the mouth, home for more than 400 types of bacteria, is the perfect host. Some of these bacterial guests are good guys that live in the mouth symbiotically and play a part in defending the body against infection by harmful bacteria. Other bacteria could kill us andif they found their way via the bloodstream superhighway to other parts of the body, such as the brain, liver and heartthey would.
Under certain circumstances, the harmful bacteria may cause periodontal disease. But precisely which factors trigger bacteria to cause this disease is still a scientific mystery, Ebersole says.
"For decades, there appeared to be an easy answer: If you didn't brush your teeth, you'd get periodontal disease. But we now know that this answer is generally wrong," he says.
"There's no doubt that if you brush your teeth and floss, you will improve the health of your gums. But there is clearly a portion of the population that has very poor oral hygiene and yet does not get periodontal disease. There is also evidence that some people can take very good care of their teethbrushing and flossingand still get this disease. So it's not just a matter of the amount of bacteria in the mouth."
In trying to solve the mystery of periodontal disease, scientists become detectives. First, they identify potential suspectsindividual bacteriaand examine them to determine their possible relationship with the disease. In this work researchers aren't starting from scratch. By now, the usual suspects in periodontal disease have been implicated in an array of medical problems.
Secondly, scientists are looking at known accomplices such as inflammation and genetics. The researchers hope these investigations will help them discover what causes periodontal disease, an important step to prove the further cause and effect between the disease and the incidence of pre-term and low-birthweight infants.
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