July 16, 2012 -- Children who received a common type of dental filling had slightly worse social behavior five years later compared to those who had different fillings, according to new research.
"Some tooth-colored fillings known as composites were associated with worse social behavior in children age 11 to 16 at the end of the study," says researcher Nancy Maserejian, ScD, an epidemiologist and senior research scientist at the New England Research Institutes.
"The composites that were associated with these problems include a chemical called bisGMA," she says. The chemical bisphenol A or BPA is used to create bisGMA.
BPA has been widely used for decades in the making of hard plastic food containers, the lining of metal food and beverage cans, and other products. Some studies have suggested that BPA, because it mimics the effects of the hormone estrogen, may affect reproduction and development.
Environmental groups say it should not be used in any products children use. Over the past few years, it has been phased out of baby bottles and other products.
BPA is also found in the air, dust, and water, so exposure is widespread.
The finding was a surprise, Maserejian tells WebMD. However, Maserejian also says the research is preliminary and the differences found were small.
The findings, she says, should not affect dental practices at this time. "We need additional studies not only to replicate the findings but also to help understand why," she tells WebMD.
The study is published in Pediatrics.
Dental Fillings and Kids' Behavior: Study Details
The new study looks more closely at some of the data gathered during the New England Children's Amalgam Trial (NECAT).
This trial was set up to look at the effects of dental amalgam -- the silver fillings -- and compare them to other fillings, known as composite or tooth-colored -- over five years of follow-up in more than 500 children.
The researchers found no harmful effects of the amalgam. They published that report in 2006.
They did find worse behavioral outcomes for those who had fillings that weren't amalgams. For the new study, they looked more closely at these differences.
There were two types of composite fillings studied. Only one uses BPA to create the filling.
The researcher looked at social and behavioral functioning of 434 of the children in the original study.
The researchers assessed the children's behavior by parent report and, for older children, their own self-reports.
Those with the fillings created with BPA reported more anxiety, depression, social stress, and interpersonal relations problems.
The link was stronger when the fillings created with BPA were on chewing surfaces. When the fillings are on chewing surfaces, wear and tear of the filling over time may be more likely, the researchers say.
The researchers found a link, not cause and effect, and the differences were small, Masserejian says.
For instance, on an assessment where the average score is 50, children who had the BPA-releasing filling were about two to six points below average.
"You probably wouldn't notice in most children that small of a difference on a personal level," she tells WebMD.
Dental Fillings and Kids' Behavior: Perspectives
There is no cause for concern at this time, say two dental experts who reviewed the findings for WebMD.
More research is needed, says Paul Casamassimo, DDS, director of the American Academy of Pediatric Dentistry's Pediatric Oral Health Research and Policy Center.
"We need to be constantly vigilant with kids and look at what we do and find out if these are valid findings over the long term," says Casamassimo, chief of dentistry at Nationwide Children's Hospital in Columbus, Ohio.
"It's a surprise finding that needs to be verified," says Mary J. Hayes, DDS, a spokeswoman for the American Dental Association (ADA) and a pediatric dentist in Chicago.
According to the ADA, BPA can become part of dental fillings or sealants, typically as a byproduct of other ingredients that degrade over time or as a trace material when it is used as a starting ingredient.
The ADA says a typical one-time exposure of BPA from a dental sealant with bis-GMA in a typical child would be two to five times lower than the estimated daily exposure from food and the environment.
BPA doesn't belong in dental fillings for children, says Alex Formuzis, spokesman for the Environmental Working Group. "No product that is used on children or that children are exposed to should contain this toxic chemical."
A spokesperson for the Dental Trade Alliance, an industry group, declined to comment on the findings.
No response was received from Dentsply Caulk, a dental materials manufacturer.
Message for Parents
Maserejian and her team have begun a new study measuring urinary BPA levels in children who have received dental fillings
Until more research is in, Maserejian says, "parents can just try to prevent cavities."
According to the CDC, that is best done by starting good oral health habits early, including: