First, a number of sealants and composites contain BPA, a known endocrine disruptor. Recent studies have further detailed the health impact of this substance, (Source)
Obviously, this is of some concern, especially since these materials are used not just for fillings but sealants, which are often recommended for children at high risk of decay. Research suggests that BPA may affect how reproductive systems and brains develop. Exposure to this chemical has also been linked to a wide variety of problems, including early puberty, metabolic disorders such as obesity and diabetes, heart disease, infertility, thyroid dysfunction, and some cancers
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The latest research, the first large BPA study in humans, published last month by the prestigious Journal of the American Medical Association (JAMA), found a “significant relationship” between exposure to the ubiquitous estrogenic chemical and heart disease, diabetes, and liver problems. Long-standing research points to hormonal disturbances and a variety of cancers and neurological and behavioral problems in adults and children. Also, the National Toxicology Program, part of the Department of Health and Human Services (HHS), has raised concerns about BPA. Of particular concern is childhood exposure BPA that leaches 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 (CDC) found detectable levels of BPA in 93 percent of urine samples collected from more than 2,500 adults and children over the age of six. BPA may accelerate puberty and raise a potential risk of cancer and, this month, the journal Environmental Health Perspectives reported that BPA might interfere with chemotherapy treatment.
Additionally, a new review of the FDA’s “BPA is safe” rationale shows that to be flawed (Source)
Despite these concerns and overwhelming evidence pointing to its dangers, the American Dental Association remains strongly in favor of BPA composites and sealants. “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.” But, in actuality, 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 CDC studied the effects of two dental sealants on 14 men, based on saliva and urine samples and found vast differences based on the sealant used. In 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.
Even if BPA weren’t an issue, there are other problems with sealants. For starters, direct cured resins such as sealants and composites are never completely polymerized. Consequently, as research by Mark Latta has shown, the material is not fully inert even after placement and can damage any of the delicate periodontal tissues it touches (the gums). In some cases, it may trigger an allergic or immune response.
Further, sealants have been implicated in the development and aggravation of neurocutaneous syndrome (NCS). This disorder is characterized by pus-filled leisons on the skin and painful and irritating sensations on or just under the skin. The sores, of course, make the individual vulnerable to other infection. Dr. Omar Amin in particular has documented many, many cases of NCS over the years and has argued from his research that there is a direct cause-effect relationship between toxic dental materials such as sealants and the development of NCS. This is appears largely due to the presence of toxins such as zinc oxide and ethyltoulene sufonamide in sealants. (You can read more of Dr. Amin’s findings here [PDF].)
Most composite resins available today do contain this endocrine-disrupting chemical or related compounds. One recent study found that of the 130 products its authors looked at, over 86% were based on BPA derivatives. Just 18 composites were free of those compounds..
While we are able to excrete some BPA, were each exposed to so much of it every day, we may not be able to clear it so efficiently. BPA is a fat-soluble compound and may accumulate in the fatty tissues of your body.
Environ Health Perspect. 2009 May; 117(5): A210.
Bisphenol A, Chapter 2: New Data Shed Light on Exposure, Potential Bioaccumulation
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Bisphenol A (BPA), an industrial chemical used in a variety of consumer products, is ubiquitous in the modern environment, with residues found in the urine of an estimated 93% of Americans over 6 years of age, according to data from the 2003–2004 National Health and Nutrition Examination Survey (NHANES). Recent research indicates that BPA acts as an endocrine disruptor and may increase the risk of heart disease, diabetes, and liver problems in adults. Until now, most exposure was thought to occur through diet, and the chemical was thought to clear the body quickly and completely. But a new study shows that urine BPA levels of subjects who had fasted for several hours were not as low as expected, suggesting either nondietary exposures or accumulation in fatty tissue, or both [EHP 117:784–789; Stahlhut et al.].
Open Dent J. 2016; 10: 446–453.
Published online 2016 Aug 31. doi: [10.2174/1874210601610010446]
Bisphenol A Release: Survey of the Composition of Dental Composite Resins
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Bisphenol A (BPA) is an endocrine disruptor with potential toxicity. Composite resins may not contain pure BPA, but its derivatives are widely used. Several studies found doses of BPA or its derivatives in saliva or urine of patients after composite resin placement.
The aims of this study were to establish an exhaustive list of composite resins marketed in Europe and their composition, and to assess the extent of BPA derivatives used.
A research on manufacturers’ websites was performed to reference all composite resins marketed in Europe, then their composition was determined from both material safety data sheets and a standardized questionnaire sent to manufacturers. Manufacturers had to indicate whether their product contained the monomers listed, add other monomers if necessary, or indicate “not disclosed”.
160 composite resins were identified from 31 manufacturers and 23 manufacturers (74.2%) responded to the survey. From the survey and websites, the composition of 130 composite resins (81.2%) was: 112 (86.2%) based on BPA derivatives, 97 (74.7%) on bis-GMA, 17 (13.1%) without monomer derived from BPA (UDMA, sometimes with TEGDMA) and 6 (4.6%) with UDMA (only); 1 (0.8%) did not contain a BPA derivative or UDMA or TEGDMA. Pure BPA was never reported.
This work has established a list of 18 composite resins that contain no BPA derivative. Manufacturers should be required to report the exact composition of their products as it often remains unclear or incomplete.
Over the past decade, the BPA derivative known as Bis-GMA has been the predominant dental filler, going into the mouths of some 100 million Americans a year, according to one expert. And now a study in the journal Pediatrics is linking Bis-GMA fillings to worse behavioral outcomes in children.
This isn’t the first time dental fillings have come under scrutiny. These off-white plastic composites are the supposedly safe alternatives to silvery mercury amalgam fillings, which have raised a number of neurotoxicity concerns. The FDA considers mercury amalgams safe, although countries like Norway and Denmark have banned the use of mercury in fillings (PDF). For largely aethestic reasons, the composite fillings have exploded in popularity and now outnumber amalgam fillings 10 to 1.
The researchers actually set out to investigate the potentially adverse effects of the amalgams. To their surprise, it was the Bis-GMA composite fillings that were associated with worse scores on behavioral assessments in categories such as maladjustment and anxiety.
The five-year study surveyed the parents of 534 children, ages 6 through 10, who were randomly assigned either amalgam or composite fillings. The results were dose-dependent: Kids with a greater number of composite fillings scored worse than those with fewer—an effect not seen with amalgam fillings. This, along with the random assignment of filling types, helped the scientists rule out statistical confounders, bolstering the possibility of a causative link between the Bis-GMA and the lower behavioral scores.
Bis-GMA fillings may present problems for kids at risk of having behavioral problems.
The effect was subtle, however—just a few percentage points. “The average behavioral differences were very small, and they probably wouldn’t be noticeable in most children,” explains lead author Nancy Maserejian, a senior scientist at the New England Research Institutes. But Bis-GMA could present problems for children who are considered at risk for behavioral problems.
The mechanism by which Bis-GMA might affect behavior is unknown. As an endocrine disruptor, BPA has been linked to anxiety and depression, though it is unclear whether fillings made from Bis-GMA—which consists of a BPA molecule chemically bonded to a molecule called glycidyl methacrylate—actually release BPA over time. Another study, involving only 19 children, found elevated BPA levels in kids’ urine after they received Bis-GMA fillings—possibly the result them ingesting trace amounts of residual BPA during the procedure. The American Dental Association contends that this one-time exposure is two to five times lower than the estimated daily exposure from food and other sources.
Bis-GMA fillings do degrade over time—most last fewer than eight years. Studies during the 1990s showed that Bis-GMA may release endocrine disruptors, but those studies used fillings that since have been phased out, according to Jeffrey Stansbury, a professor of restorative dentistry at the University of Colorado-Boulder.
The FDA seems unlikely to ban Bis-GMA fillings, as it recently refused to ban BPA in food-can linings.
The existing alternatives to mercury amalgam and Bis-GMA composite fillings are seldom used. One of them is urethane dimethacrylate, which isn’t associated with any behavioral effects, but it looks less natural in the mouth and doesn’t last as long as the other types. It’s a tricky balance: Dental fillers must be pliable enough to pack into a cavity and get hard enough to withstand daily chewing—yet not too hard so as to wear down the enamel on neighboring teeth.
Stansbury says 3M makes a product called Filtek that could work as an alternative. But it requires a different technique to apply, and inertia in the dental community has kept it from gaining popularity. So unless the FDA bans Bis-GMA in dental fillings—not likely, since it recently refused to ban BPA in can linings—or patients start demanding better options, it’s likely to remain that way.