Enough uncertainty surrounds silver-colored metal dental fillings with mercury that U.S. regulators should add more cautions for dentists and patients, a U.S. advisory panel said Wednesday.

While past data have backed the cavity treatment, the fillings should be accompanied by warnings about unknown risks for vulnerable people such as children and pregnant women, the Food and Drug Administration’s panel of outside advisers said.

“There really is no place for mercury in children,” Suresh Kotagal, a panelist and neurologist at the Mayo Clinic in Rochester, Minnesota, said of the toxic metal.

Metal fillings are used in millions of Americans’ teeth to patch decay, but are increasingly being rejected in favor of bone-colored resin that is more eye-pleasing.

Mercury has been linked to neurological damage at high exposure levels and makes up about half of a metal filling.

While the FDA has said no specific new evidence has emerged about the fillings’ safety, the agency wants input on how it assessed the data and drew conclusions after receiving four petitions questioning its 2009 ruling.

While the panel stopped short of urging a ban, it wants the FDA to look at the latest data and reassess its guidance after the agency last year declared the fillings safe.

Their advice follows a divisive two-day public meeting on the FDA’s handling of such fillings, also known as dental amalgam.

The FDA could decide to continue backing the metal fillings, urge more cautious use or ban the products. Some European nations have banned amalgam.

The agency’s actions could affect dental filling makers such as Dentsply International Inc. and Danaher Corp.’s Kerr unit, and distributors such as Henry Schein Inc. and Patterson Cos.

Critics told the advisers there was a clear link between mercury fillings and side effects, especially in more vulnerable patients. They should be banned or not implanted without patient consent, they said. But some dentists and trade groups said data show the fillings pose no harm once set in a patient’s tooth.

“Dental amalgam is an appropriate option to offer patients,” said Leslie Grant, a past president of the National Dental Association, which represents black dentists. Grant added that the cost-effective fillings help prevent further tooth decay or loss in poorer people.

Other dentists testified that mercury was too risky and that they no longer use such filings. Dozens of patients also detailed how their health deteriorated after getting amalgams and urged the panel to push FDA to  initiate strong warnings, especially for children and pregnant women.

The at-times rancorous public testimony, which drew two police officers as a precaution, elicited applause, boos and gas mask props from vocal critics.

“The agency so far has taken no steps to protect this most vulnerable population,” Sylvia Dove, a member of the group Consumers for Dental Choice, told the panel Wednesday.

The FDA’s advisers were mixed on the benefits and risks of amalgam. Some said data support it while others said it was unnecessary when alternatives are less risky. Most said it should remain an option as long as patients are clearly told the risks. Panelists disagreed on whether resins are a costlier and less durable alternative.

They raised questions about older scientific methods used to assess mercury and expressed concern that some studies FDA weighed in making its 2009 ruling were outdated.

“Clearly, FDA needs to take a new look at recent literature,” said panelist Judith Zelikoff, an environmental health professor at New York University School of Medicine.

Anthony Watson, head of the FDA’s division that oversees dental devices, said officials have grappled with the issue for decades. Even if the FDA reviews newer data, “We could end up in the same situation where we are now — in that the data are inconclusive,” he told panelists.

Though the FDA earlier said it would not necessarily take new regulatory action, Watson said the agency was poised to make some decisions soon: “Obviously everybody in this room wants something to happen quickly and so do we.”