It's a relatively small change - a rewritten page buried deep in the Food and Drug Administration Web site that will list possible health hazards from the use of mercury in dental fillings.
But for a small, vocal group of advocates, it's the culmination of a 32-year battle against the dental establishment, as well as a 10-year lawsuit against the government to force official recognition of their position that these common dental repairs may be a cause for concern.
FOR THE RECORD - A photo caption in a HealthToday article about mercury-based dental fillings yesterday incorrectly stated the length of time Dr. Michael Baylin has been practicing in Pikesville. He has been there 33 years.
The Sun regrets the errors.
"I'm really glad that people are starting to wake up to this and realize that putting mercury toxins into our bodies has consequences, and that we need to protect the public," said Gabrielle Hart, a Northwood mother of two and member of Moms Against Mercury, which has struggled with the FDA over the issue.
Under the terms of a lawsuit settlement reached in June, the FDA agreed to finish "classifying" dental mercury and the amalgam fillings that contain it by July 28, 2009 - an agreement that critics call a victory for their cause.
It means the agency will officially investigate and list the possible hazards involved with mercury-based fillings, a process it has delayed for those 32 years. The results will be posted on the FDA Web site.
The American Dental Association, which represents 156,000 American dentists, insists that dental fillings containing mercury are safe. The group cites repeated studies which, it says, prove that such fillings have no ill effects.
The organization also discourages dentists from routinely replacing sound, mercury-based fillings with materials that contain less toxic ingredients.
Still, critics note that dental amalgam is composed of 40 percent to 50 percent mercury, a neurotoxin that can damage the immune system and cause a variety of speech, hearing and vision problems.
Young children are especially vulnerable to its effects, and the government has warned pregnant women and young children to limit their consumption of fish with relatively high mercury levels.
Manufacturers have also removed the mercury-based preservative thermiosol from most children's vaccines. For years, vocal parents have charged that the mercury in vaccines caused autism and other problems in their children, an assertion the government and most scientists vehemently dispute.
For dental use, mercury is mixed with an alloy powder of silver, tin, copper and zinc, and in this so-called "encapsulated" form, most dental authorities say it is perfectly safe.
Dentists in the United States have used it for more than 150 years because it's durable and relatively easy to work. The main alternative filling material is a white resin, which is more aesthetically pleasing because it matches tooth color but generally does not last as long.
According to the trade publication Dental Products Report , 67 percent of dentists use amalgam filings, and most people with fillings have one or more made from amalgam. But critics cite other surveys showing that 72 percent of dental patients aren't aware their fillings contain mercury. This bothers even some who say they believe amalgam is safe.
"Patients need to know what's being placed in their mouths," said Dr. Howard E. Strassler, director of operative dentistry at the University of Maryland Dental School. "Tens of millions of Americans have amalgam in their mouths."
Critics say there are still plenty of concerns about dental amalgam, particularly regarding the developing fetuses of pregnant women.
As a byproduct of the amalgam fillings, small amounts of mercury are released in vapor form, particularly among patients who grind their teeth. The question is how much of a danger this represents.
Dr. Shane S. Que Hee, a professor of environmental health sciences at the University of California, Los Angeles School of Public Health, said the risk "depends on how eroded [the filling] is." As amalgam fillings get old, they deteriorate, increasing the chance of mercury leeching out.
"If they're pretty new, they're pretty safe," said Que Hee. It takes five to 10 years for a filling to start showing signs of wear, he said.
There is little scientific evidence of direct mercury poisoning from amalgam fillings. In 2006, the Journal of the American Medical Association published the results of a five-year study concluding that there was no significant difference in the average IQs of children with amalgam fillings and those with resin fillings.
"Studies over and over again show no long-term effects," said Dr. Caroll-Ann Trotman, associate dean for academic affairs at the University of Maryland Dental School.
As a result, the FDA says patients should not have their amalgam fillings routinely replaced unless they are damaged or fall out, a position echoed by the dental association and many practitioners.