Dueling Docs: Are Dental Sealants Safe for Kids?

Five-to-10-year-olds who used sealants had less than half the tooth decay on biting surfaces five years after treatment than those who brushed regularly. But are they safe?
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The Issue:
Dental Sealants for kid

The Facts

Look Ma No Cavities! In an ad campaign worthy of Mad Man's Don Draper, Crest exhorted TV audiences of the 60s and 70s to use its Fluoristan-enriched toothpaste to help prevent cavities in kids. Now dentists have added a newer approach: seal children's back teeth with air-tight plastic shields known as dental sealants.

Sealants are meant for the chewing surfaces of molars, particularly those with many pits and fissures, though many dentists apply them routinely to all their young patients as soon as their pre-molars and molars erupt - at around age six and 12. According to the American Dental Association, sealants, which last for several years, work by "'sealing out' food and plaque... [because] toothbrush bristles cannot reach all the way into the depressions and grooves."

Indeed, a review study last fall by the Cochrane Collaboration, a group that evaluates medical research, found that 5- to 10-year-olds who used sealants had less than half the decay on biting surfaces five years after treatment than those who brushed regularly.

But are they safe? Hermetically sealing a tooth may sound odd, if not unnecessary, but what has concerned researchers through the years is that dental sealants can contain the same chemicals that caused controversy when present in plastic baby bottles: bisphenol-A (BPA) or its chemical cousin, bisphenol-A dimethacrylate (BPA-DMA). Though still investigating, the FDA currently deems these compounds safe, but some researchers have impugned them in everything from diabetes, cancer and - most alarming for children - to accelerating the onset of puberty due to estrogen-like effects.

The alarm over the BPA compounds was so fever-pitched that some sealant companies like Ultra Seal set out to study its own sealants and report they contain zero BPA. Other companies, like Dentsply still produce some of its Delton sealants with BPA-DMA, but new formulations aren't made with it. And 3 M says its Clinpro sealant is not manufactured with BPA either.

Are we safe yet?

Two experts debate the issue: Joel Berg, spokesperson for The American Academy of Pediatric Dentistry and chairman 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

The debate
Dr. Joel Berg:

Berg explains that the compound used in most sealants today is called bis-GMA, a product that derives from both BPA and BPA-GMA but has different properties.

"When you synthesize BPA and bisphenol A dimethacrylate, you get bis-GMA, a much larger compound. Generally larger molecules are much less likely to leach and much less absorbable in the mouth. Even if they did release into the mouth, there has never been any study showing any concern with these larger molecules It's the small molecules that you worry about. They can move around and attach. Not the large ones."

Berg concedes however that bis-GMA is not necessarily pure. "Using modern, highly sensitive tools, one can still detect trace amounts of BPA or BPA-DMA. But the question of toxicology is a question of dose. Trace amounts are the amount of things you breathe in the air, and in what you drink. You can find a few molecules per billions of BPA in dental sealants today. But it's like NYC drinking water. It's among the cleanest drinking water in the U.S., yet with sensitive tools, you can detect trace amounts of lead and mercury."

Meantime, says Berg, "I still strongly recommend sealants regardless of trace amounts of BPA. Not every child needs sealants. If a kid's molars are notably smooth, that child doesn't need sealants, but for the rest, if you don't seal a molar that would otherwise be susceptible to bacteria, it will probably need a filling and at some point the filling will fail. That tooth may then need a crown and root canal. The point is: sealants are preventing that whole process from the beginning."

What should parents do if their children received sealants that have the two questionable compounds? "We don't know," says Berg, "There is certainly more BPA and BPA-DMA released back in many of the old sealants than in most of them today. But even when those children were getting sealants, they still got more exposure of BPA and BPA-DMA from sources other than sealants, like vegetable cans and plastic. The volume in a lining of a can is large, covering the entire surface of a can and sits there leaching away. We don't know the true level of BPA that leeched out to kids and their level of exposure. What we know is that today, most sealants don't have those ingredients."

Berg reminds parents that "Plaque is like email - it comes in your inbox everyday, you delete it and it comes right back again." Even with sealants, you have to be diligent about brushing and flossing every day to remove plaque from the flat surfaces on the sides and in between teeth. Sealants prevent plaque from invading the pits and crevices on the chewing surfaces of molars where bacteria can go and eat away. Creating a barrier cuts off plaque's nutrient supply. Given that there may be only trace amounts of BPA in most sealants, the benefit of sealants probably far outweighs the potential risks."

Dr. Frederick S. vom Saal:

"It's absolutely right that the current compound used in many dental sealants, bis-GMA, is not biologically active. And I do agree that bis-GMA is a better product than the other two; it's definitely more stable. But don't tell me that trace amounts of BPA and BPA-DMA don't matter. That's not true for these chemicals. Even when it comes to parts per billion, it matters."

"At a meeting of National Institutes of Health in 2006, 36 international experts said with confidence that we believe trace amounts of these compounds pose a threat and anyone who is ignorant of that should not be making statements about its safety."

Generally, vom Saal sends strong warnings about BPA. He says, "BPA acts like an estrogen and the use of bis-GMA may still expose kids to estrogen. In animal studies, BPA is associated with prostate and mammary cancer and damage to the ovaries. Children have their teeth sealed at an early stage in life. With BPA, we are increasing estrogen in kids at a time when it shouldn't be there. We're dealing with a time in life when there is a lot of development and we just don't exactly know what the consequences are of adding something like this 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 to reproductive organs. This is why it is called an endocrine disrupting compound."

But, as far as bis-GMA, the larger compound found in most sealants vom Saal says: "If in fact bis-GMA is really stable and completely polymerized then I would like to see data from a real life situation, from checking in someone's mouth, then I'll say fine, I have no problem with bis-GMA. But we don't have that data."

"When someone says, 'Oh - just a little bit remains, don't worry about it. That's what they told you about lead - it's just not true. It's the current insanity of our risk assessment system that demands that the government make statements to the American public about what is safe, when those statements are based on assumptions and guesses. 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's producing the product."

"It is also not an appropriate response for someone in the public health sector to suggest that if there are other things in the world that are dangerous, like mercury in our water, then we shouldn't worry about the trace parts in the sealants. We should do what we can to reduce risk of exposure to chemicals known to be hazardous, particularly for our children."

However, says vom Saal: "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 that the dentist is doing everything to limit exposure during placement of the sealants. What is the exposure after chewing, we don't know. But every drug and every medical treatment typically has some risk. Parents need to weigh that risk against not doing anything."

"Bis-GMA is not new. For at least a dozen years, there's been a lot of argument over bis-GMA, too. Why isn't the dental industry doing really good studies and publishing finding for dentists? You don't just yell at each other. Scientists don't do that. Saying that trace amounts are harmless is just an opinion- but I want is a study. It is an obligation on the part of the medical community to continue to look into whether the product is achieving the goals it set out to achieve. But the dental industry has not aggressively sought data."

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