Dentists Back Sealants, Despite Concerns
Cavities or chemicals? That’s the dilemma for parents worried about a controversial substance found in the popular sealants that are painted on children’s molars to prevent decay.
The chemical is bisphenol-A, or BPA, which is widely used in the making of the hard, clear plastic called polycarbonate, and is also found in the linings of food and soft-drink cans. Most human exposure to the chemical clearly comes from the food supply. But traces have also been found in dental sealants.
Although the Food and Drug Administration has reassured consumers that the chemical appears to be safe, it has received increasing scrutiny in recent months from health officials in the United States and Canada.
The National Toxicology Program, part of the Department of Health and Human Services, has raised concerns about BPA, particularly over childhood exposure to the traces that leach from polycarbonate baby bottles and the linings of infant formula cans. The 2003-4 National Health and Nutrition Examination Survey by the Centers for Disease Control and Prevention found detectable levels of BPA in 93 percent of urine samples collected from more than 2,500 adults and children over 6.
BPA has estrogenlike effects, and animal studies have suggested that exposure may accelerate puberty and raise a potential risk of cancer. This month, the journal Environmental Health Perspectives reported that the chemical might interfere with chemotherapy treatment. And last month The Journal of the American Medical Association reported that adults with higher levels of BPA in their urine were more likely to have heart disease or diabetes.
Despite these concerns, the American Dental Association remains strongly in favor of sealants. Dentists note that numerous studies show that any exposure they cause is negligible and temporary, lasting no more than three hours after the initial application. And other studies have found no detectable levels of BPA in most American-made sealants. Meanwhile, sealants have been shown to offer years of protection against cavities.
“This is such an enormously valuable tool to prevent tooth decay,” said Dr. Leslie Seldin, a New York City dentist and consumer adviser for the American Dental Association. “The BPA issue, I think, is so minuscule in impact that it doesn’t really warrant the attention it’s been getting.”
Dental sealants have the consistency of syrup so that they can seep into the crevices of molars. A light is used to harden the sealants, which are then buffed smooth. The coatings prevent the growth of bacteria that promote decay in the grooves of molars.
Just this month, a review of 16 studies by the Cochrane Collaboration, a nonprofit group that evaluates medical research, showed sealants offered significant protection from cavities. In the seven studies that compared sealants and regular brushing alone, the 5- to 10-year-olds who used sealants had less than half as much decay on biting surfaces four and a half years after the treatment. One study with a nine-year followup found that only 27 percent of sealed tooth surfaces had developed cavities, compared with 77 percent of unsealed surfaces.
The Cochrane review did not address BPA, but it did cite a March review article in The Journal of the Canadian Dental Association, looking at 11 major studies of BPA exposure from dental sealants. That review, financed by the nation’s health system and conducted by researchers with no industry ties, concluded that patients were not at risk for exposure to the chemical. And it noted that dentists and patients could further limit any exposure with simple steps like buffing tooth surfaces and gargling and rinsing after sealants are applied, all of which are standard practices in most dental offices.
The review also found that three products did not release detectable amounts of BPA: Helioseal from Ivoclar Vivadent; Seal-Rite from the Pulpdent Corporation; and Conseal f from SDI (North America). All carried the 2007 American Dental Association seal.
The amount of BPA exposure can vary depending on the sealant. In a 2006 article in The Journal of the American Dental Association, researchers from the United States Public Health Service and the Centers for Disease Control and Prevention studied the effects of two dental sealants on 14 men, based on saliva and urine samples. They found that patients treated with an Ivoclar Vivadent product called Helioseal F showed no change in urinary or salivary levels of BPA, while patients treated with Delton Light Cure sealant, from Dentsply Ash, were exposed to about 20 times higher doses of BPA.
Linda C. Niessen of Dentsply International said in a statement that the A.D.A. says sealants are safe, and she notes that any exposure from a sealant is “significantly lower and occurs infrequently” compared with other sources of BPA.
Parents concerned about BPA exposure should ask their dentists what type of sealants they use and whether it has been tested for BPA. But researchers from the Centers for Disease Control and Prevention offered this bottom line: “Sealants should remain a useful part of routine preventive dental practice.”