NOTHING TO SMILE ABOUT
Every parent frets over what kids put in their mouths. We should also be concerned about what dentists put in our kids' mouths -- as well as our own. Before we examine the contents of sealants and fillings, however, bear in mind the good news: by using basic prevention, we may not need any of this stuff at all.
"It's just remarkable -- I'm seeing child after child with a cavity-free mouth," says Harvey Karp, M.D., a Los Angeles pediatrician who credits brushing, flossing and fluoride. Currently, most health professionals and the National PTA agree that fluoride's benefits outweigh its risks, though the PTA cautions against swallowing fluoridated toothpaste. However, fluoride cannot prevent cavities if we don't also assiduously brush, floss and avoid sugar.
Dental sealants, thin plastic coatings painted on the chewing surfaces of the back teeth, are commonly recommended by dentists to seal teeth against decay-causing bacteria. The National Institute of Dental Research (NIDR) recommends that children get sealants on their permanent molars as soon as they come in (the first set appears between the ages of 5 and 7, the second set between 11 and 14). A NIDR brochure laments the fact that, although sealants have been used since the 1960s, fewer than 20 percent of children in the U.S. have them.
However, a study conducted by researchers at University of Granada in Spain published in Environmental Health Perspectives (March 1996), reports that plastic chemicals used in dental sealants -- bisphenol A (BPA) and a related substance, bis-GMA -- act like the female sex hormone estrogen. Significant quantities of bisphenol A leach into the saliva of treated patients, the study found. The researchers took saliva from college-age volunteers before and one hour after they had been treated with one of four commercial dental resins based on BPA -- Tetric, Charisma, Pekalux, and Delton -- and compared the samples. They found 3-30 micrograms of BPA per milliliter of saliva collected after (but not before) treatment. Studies are ongoing to determine for how long the chemicals may continue to leach from the sealant.
So how bad is that? It is known from laboratory studies that BPA, at levels lower than those measured at Granada, can stimulate human cells to grow in the same way that estrogen does. Numerous studies document that the fetus is highly sensitive to hormones and hormone-like chemicals, exposure to which can lead to reproductive disorders and some cancers. But the effects on children and adults are less clear, according to Frederick vom Saal, Ph.D., of the University of Missouri-Columbia, an expert on the effects of hormones.
Dr. vom Saal notes that, while the effects are not known, the younger the individual, the more sense it makes to avoid exposure. Thus, while some dentists also recommend sealants for baby teeth, especially if they have deep pits and grooves, parents might want to think twice. Dr. vom Saal said he was "stunned" at the quantities of BPA released by dental sealants as measured by the Spanish researchers. "I would be concerned about the possibility of high levels of this chemical getting into a child. And until we learn more about its biological effects, as a parent I would therefore err on the side of caution," he recommends.
Dr. vom Saal also notes that the concern is principally with dental sealants, even though BPA-based materials are also used in plastic resin composite fillings, and could be absorbed through tissue. "The amount released is a function of the surface area, and you are pinpointing a very small area in a filling, as opposed to using the material to coat teeth."
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Written by: Lisa Y. Lefferts, M.S.P.H. reprinted from The Green Guide.
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