As Maine and other states are voting to ban BPA from baby food and formula, worry has surfaced about the effects of the now-notorious toxin in children’s dental fillings and sealants.
A new study—the first to analyze the effects on dental fillings on children’s mental health--links a widely used type of filling that contains BPA to worse behavioral and social functioning in kids five years after the filling is placed, compared to children whose cavities were treated with other materials.
The researchers found that kids ages 6 to 10 who received fillings with the BPA-based material had drops in behavioral scores on measurements of such issues as depression, anxiety, acting out, paying attention, attitudes towards teachers, and self-esteem. However, the decrease in behavioral scores after dental work was small.
Should parents worry about these fillings? To find out more, I talked to Jonathan Shenkin, DDS, MPH, a faculty member in health policy and pediatric dentistry at Boston University and a spokesperson for the American Dental Association (ADA).
There are two main types of fillings: metal ones known as amalgam and tooth-colored fillings called composites, that are made from glass or quartz filler and bonded into cavities. Because composites match the color of the patient’s teeth, they’ve become very popular, says Dr. Shenkin.
In the study, the problematic fillings were a type of composites that include the resin bis-GMA, which can contains small amounts of BPA (bisphenol-A), used in the manufacturing process. This dental material is also used in sealants (a protective covering that’s applied to kids’ teeth to reduce risk for cavities).
BPA was banned from baby bottles and sippy cups last year because it mimics the effects of estrogen, and may harm health. (The FDA expressed concern about the potential effects of BPA on the prostate glands, brains and behavior of infants and young children.)
Used to make plastics, BPA is found in some food packaging, which can include food or beverage cans. A recent study linked prenatal exposure to hyperactivity and anxiety, especially in girls. In addition, exposure to endocrine disrupting chemicals, including BPA, may be associated with autism spectrum disorder and ADHD, according to a literature review of 17 studies.
Children with higher levels of BPA in their urine were more likely to be obese, according to a study published in the Journal of the American Medical Association last year. BPA exposure in kids has also been tied to higher risk for kidney and heart problems.
The amount of BPA in composites is very small, says Dr. Shenkin. “The amount in dental material is only a fraction of what’s found in food containers. Usually, there’s only a one-time exposure to traces of BPA residue when the cavity is filled.”
According to the ADA, if a child gets six dental sealants containing bis-GMA, the estimated one-time exposure is about 5.5 micrograms, which is two to five times lower than the estimated daily exposure to BPA from food and environmental sources.
Another type of composites, which contain bis-DMA (which also uses BPA as a starting ingredient during manufacture), can cause ongoing exposure to BPA since salvia can break down that type of resin. However, bis-DMA composites are rarely used in dental practice, says Dr. Shenkin.
The study, published in the journal Pediatrics, looked at data collected from 534 children aged six to 10 in six different dental clinics between 1997 and 2005. (434 children were observed during the follow-up phase of the study.)
Kids with cavities were randomly assigned to be treated with amalgam (metal) or composite fillings, then were tracked via reports from their parents using checklists to rate emotional symptoms and psychological adjustment.
Compared to kids who received metal fillings, those treated with composites had:
"On average, the difference in social behavior scores were very small and would probably not be noticed for each individual child," lead study author Nancy Maserejian, ScD told HealthDay. "But imagine a huge group of children around the country; you'd probably notice a difference."
The behavioral problems were associated most strongly with higher exposure to BPA, and fillings in the back of the month. This may be because these fillings suffer the most wear and tear when kids chew their food. As the fillings wear down, they may release chemicals that are swallowed.
However, there could be another explanation for the findings, says Dr. Shenkin. “Typically, kids who get cavities drink a lot of sugary beverages, such as soda, from cans that can contain BPA, so if this chemical causes anxiety and other behavioral problems, the culprit could be the kids’ diet.”
The researchers didn’t measure BPA levels before and after the fillings.
Amalgam fillings are generally considered safe. Although they do release some mercury vapor, these levels are widely believed to be low enough to avoid brain and kidney damage, linked with higher amounts of the vapor. Therefore, there’s no need to replace this type of filling, a practice that’s grown in popularity due to fears about mercury.
“Removing sound amalgam fillings results in the loss of healthy tooth structure, and exposes you to additional mercury vapor released during the removal process,” the FDA explains on their website.
The best way to avoid having to make decisions about which fillings to use is to take steps to prevent cavities:
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