Bisphenol A (BPA) has hit the news once again, and the ADA has confirmed that many popular root canal sealers contain BPA.
Last month Health Canada declared BPA toxic, making it easier for the government to regulate the use of the chemical. And earlier this year, the U.S. National Institute of Environmental Health Sciences launched 11 new animal studies to investigate the possible effects of BPA, and the FDA issued new cautions to consumers recommending they limit their exposure to BPA.
What is BPA? It is an organic compound that contains two phenol groups. It combines with salivary enzymes and is used increasingly in dental sealants, resin fillings, and root canal cements. It is cumulative from many sources and is absorbed systemically.
BPA is found in plastics, such as baby bottles and all containers that have Nos. 6 and 7 on the bottom. It is linked with breast cancer (Hormones and Cancer, June 2010, Vol. 1:3, 146-155), prostate cancer (Reproductive Toxicology, October 7, 2010), heart disease, and diabetes, and sexual dysfunction was a major problem with male employees in Chinese factories that use BPA in making epoxy resins.
BPA has also been associated with changes in behavior, prostate and urinary tract development, and early onset of puberty. A 2008 study in the Journal of the American Medical Association describes the association of urinary BPA concentrations with medical disorders and laboratory abnormalities in adults and the risk of other metabolic disorders (September 17, 2008, Vol. 300:11, pp. 1303-1310).
The ADA in its fall 2008 issue of the Professional Product Review (the publication of the ADA Council on Scientific Affairs) lists BPA and bisphenol A glycidyl methacrylate (bis-GMA) resins in these products: AH Plus Jet (Dentsply), Epiphany root canal sealant (Pentron Clinical Technologies), EZ-Fill (Essentil Dental Systems), RealSeal sealer (SybronEndo), and Resinate sealer (Obtura Spartan).
Dentists should inform their patients of the dangerous potential of these root canal sealers. Would you want them used on your spouse, children, or grandchildren? We do not know if the amount used in making these conventional sealers contain minimal amounts of BPA or dangerously toxic levels. Who knows at this point what dangerously toxic levels are? Any amount may be dangerous, since BPA is located in so many products that each one adds to the accumulated level that will cause cancer and other serious problems.
In the Professional Product Review, several dentists and educators discuss endodontic filling and sealer materials. One panelist said sealers have been shown to be very inflammatory when freshly mixed, and it is the goal of dentists to keep filling materials confined within the canals. But we all know that, on occasion, depending upon the case or the type of techniques, sealers are being extruded beyond the apex of the root canal. In other words, it is extruded into the tissues. BPA cannot be controlled enough to be certain it remains within the canal -- no matter what technique is used. And before a root canal cement sets, it is still soft and in contact with apical tissue to which it is exposed.
The ADA recommends that after using a sealant and fixing it with the curing light, practitioners should wipe the unpolymerized layer with a cotton applicator. Where does the unpolymerized layer start and where does it end? In fact, a trace amount of BPA can be detected in the saliva after sealant placement.
Do we have the right not to inform our patients that the root canal sealer containing BPA will be used and sealed into their tooth canals or is being used on our pediatric patients as sealants? In 20 years, will our children or grandchildren have a high incidence of cancer, caused by the dental profession? Are our dental researchers letting us down? If so, what is the motive? Incompetence? Ignorance? Or financial gain overcoming scientific knowledge?
These are the questions dentists should be asking about BPA.
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