Issue:
Dental sealants for children
Look Ma No Cavities! In an ad campaign worthy of Mad Man’s Don Draper, Crest urged television audiences of the 60s and 70s to use fluoride-enriched toothpaste to help prevent tooth decay in children. Now dentists have added a newer approach: sealing children’s back teeth with airtight plastic shields known as dental sealants.
Sealants are intended for the occlusal surfaces of molars, particularly those with many cavities and fissures, although many dentists routinely apply them to all their young patients once their premolars and molars have erupted – around the ages of six and 12. The American Dental Association, sealants, which last for several years, work by “sealing” food and plaque… [because] The bristles of the toothbrush can’t reach deep into the grooves.”
Indeed, a review study last fall by the Cochrane Collaboration, a group that evaluates medical research, found that children ages 5 to 10 who used sealants had less than half the decay in their biting surfaces five years after treatment in compared to those who brushed regularly. .
But are they safe? Hermetically sealing a tooth may sound strange, if not unnecessary, but what has concerned researchers for years is that dental sealants may contain the same chemicals that cause controversy when found in plastic baby bottles: bisphenol-A (BPA ) or its chemical cousin. bisphenol-A dimethacrylate (BPA-DMA). Although still under investigation, the FDA currently considers these compounds safe, but some researchers have questioned them in everything from diabetes, cancer, and—most worryingly for children—accelerating the onset of puberty because of effects that look like with estrogen.
The alarm about BPA compounds has been so feverish that some sealant companies such as Ultra Seal have begun to study their own sealants and report that they contain zero BPA. Other companies such as Dentsply still produce some of their Delton sealants with BPA-DMA, but no new formulations are made with it. And 3M says its Clinpro sealant isn’t made with BPA either.
Two experts discuss the topic: Joel Berg, spokesman for the American Academy of Pediatric Dentistry and chair of pediatric dentistry at the University of Washington in Seattle, and Frederick S. vom Saal, Ph.D. professor of Biological Sciences at the University of Missouri
Berg explains that the compound used in most sealants today is called bis-GMA, a product derived from both BPA and BPA-GMA but with different properties.
“When you combine BPA and bisphenol A dimethacrylate, you get bis-GMA, a much larger compound. Generally the larger molecules are much less likely to be washed out and much less absorbable in the mouth. Even if they were released in the mouth, there’s never been a study showing some concern with these larger molecules. It’s the small molecules you’re worried about. They can move and stick. Not the big ones.”
Berg admits, however, that bis-GMA is not necessarily pure. “Using modern, highly sensitive instruments, one can detect traces of BPA or BPA-DMA. But the question of toxicology is a matter of dose. Traces are the amount of things in the air you breathe and in the things you drink. You can find a few molecules per billion of BPA in dental sealants today. But it’s like New York drinking water. It’s some of the cleanest drinking water in the US, but with sensitive instruments you can detect traces of lead and mercury.”
In the meantime, says Berg, “I highly recommend BPA-free sealants. Not every child needs sealants. If a child’s molars are especially smooth, that child doesn’t need sealants, but for the rest, if they don’t need a molar seal that would otherwise be susceptible to bacteria, will probably need a filling, and at some point the filling will fail. That tooth may then need a crown and a root canal. The thing is: fillings prevent that whole process from happening.”
What should parents do if their children received sealants that have the two questionable compounds? “We don’t know,” says Berg, “There’s certainly more BPA and BPA-DMA released in many of the old sealants than in most of them today. BPA and BPA-DMA from sources other than sealants, such as vegetable containers and plastic. The volume in a box liner is large, it covers the entire surface of a box and sits there with a flush. We do not know the actual level of BPA given to the children and their level of exposure. What we do know is that today, most sealants do not have these ingredients.”
Berg reminds parents that “Tease is like email—it comes in your inbox every day, you delete it, and it comes back again.” Even with sealants, you need to be diligent with brushing and flossing every day to remove plaque from the flat surfaces on the sides and between the teeth. Sealants prevent plaque from invading the cavities and crevices on the chewing surfaces of the molars, where bacteria can go and eat. The formation of a barrier cuts off the supply of nutrients to the plaque. Since only traces of BPA may be present in most sealants, the benefit of sealants probably far outweighs the potential risks.”
Dr. Frederick S. vom Saal:
“It is absolutely true that the current compound used in many dental sealants, bis-GMA, is not biologically active. And I agree that bis-GMA is a better product than the other two, it is definitely more stable. But don’t tell me that trace amounts of BPA and BPA-DMA don’t matter. That’s not true of these chemicals. Even when it’s parts per billion, it matters.”
“At a meeting of the National Institutes of Health in 2006, 36 international experts said confidently that we believe traces of these compounds pose a threat, and anyone who ignores them should not make statements about their safety.”
In general, the vom Saal sends out strong warnings about BPA. He says, “BPA acts like estrogen, and the use of bis-GMA can still expose children to estrogen. In animal studies, BPA has been linked to prostate and breast cancer and ovarian damage. Children have been sealed teeth early in life. With BPA, we’re increasing estrogen in children at a time when it shouldn’t be there. We’re dealing with a time in life where there’s a lot of growth and we just don’t know exactly what the consequences are. Adding something like that at that time. That’s a hole in our understanding. In animal studies, if you expose BPA before puberty, you cause all kinds of changes in the reproductive organs. That’s why it’s called an endocrine disrupting compound.”
But regarding bis-GMA, the largest compound found in most sealants vom Saal says: “If in fact bis-GMA is really stable and fully polymerized, then I would like to see data from a real situation, from control someone’s mouth, then I’ll say well, I don’t have a problem with bis-GMA. But we don’t have that data.”
“When someone says, ‘Oh, there’s a little bit left, don’t worry about it. That’s what they told you about lead – it’s just not true. It is the current insanity of the risk assessment system that requires the government to make statements to the American public about what is safe when those statements are based on assumptions and guesswork. What the American people don’t understand is that when they’re told something is safe, it’s really someone’s guess — a guess that takes into account the cost to the industry that makes the product.”
“It’s also not an appropriate response for someone in public health to suggest that if there are other things in the world that are dangerous, like mercury in our water, then we shouldn’t be concerned about traces in sealants. We must do everything we can to reduce the risk of exposure to chemicals that are known to be dangerous, especially for our children.”
However, vom Saal says, “If your child, in consultation with the dentists, has a real need for them, based on a medical issue, then you want to make sure the dentist is doing everything possible to limit exposure when placing the sealants. What is the exposure after chewing, we do not know. But every drug and every medical treatment usually carries some risk. Parents have to weigh this risk against doing nothing.”
“Bis-GMA is not new. For at least a dozen years, there has also been a lot of controversy about bis-GMA. Why doesn’t the dental industry do very good studies and publish findings for dentists? you yell at each other. Scientists don’t they do that. Saying that traces are harmless is just an opinion- but I want is a study. It is the responsibility of the medical community to continue to examine whether the product is achieving the goals it set out to achieve. But the dental industry has not sought offensive data.’
