The Centers for Disease Control yesterday confirmed that a Florida dentist who died last year of AIDS appears to have infected three of his patients with the virus, not just one as had been reported earlier.

The release of the CDC report was followed swiftly by a major policy shift on the part of the American Medical Association and the American Dental Association. Both called on health care workers carrying the AIDS virus to inform patients that they are infected or stop performing risky surgical procedures.

"The recent cases of possible dentist-to-patient transmission have caused some uncertainty about the risk of transmission from physicians to patients under certain circumstances," the AMA said in a statement calling for the new restrictions to remain in effect until conclusions are reached about how much risk HIV-infected doctors pose to their patients.

"In cases of uncertainty about the risks to patient health, the medical profession, as a matter of medical ethics, should err on the side of protecting patients."

The move is a reversal of policy for both groups, which had recommended only that their HIV infected members consult with peers about the ethics and safety of conducting certain kinds of "invasive" medical procedures.

But it drew immediate and angry criticism from AIDS activists, who accused the two groups of overreacting and said that the CDC findings do not justify such sweeping restrictions on HIV-infected health care workers.

"This is a public relations gesture masquerading as a public health measure," said Ruth Finkelstein, director of research for the AIDS Action Council in Washington. "It's simply an attempt to look good."

AIDS groups pointed out that, in yesterday's report on the case of Florida dentist David Acer, the CDC conceded that it still does not know how the dentist's patients contracted HIV.

The assumption held by many about the case -- the first ever alleged transmission of HIV from a medical provider to a patient -- is that somehow in the course of dental surgery Acer cut himself and some of his blood came into contact with his patients' blood.

The CDC stated yesterday that Acer accidentally might have infected one of his patients with the blood of another, perhaps by inadequately sterilizing his instruments between patient appointments.

However, Harold Jaffe, a senior official in the CDC's Center for Infectious Diseases, said the evidence for that is mixed. The virus, for example, is easily killed by even the most rudimentary sterilization.

The CDC investigation disclosed that recommended procedures for preventing spread of infectious diseases were not uniformly followed in Acer's office. And at least two of his infected patients visited his office on the same day, making cross-infection through instruments a possibility.

"It could be either possibility," Jaffe said. "Or it could be both."

"It seems to me that both organizations are jumping the gun," said David Barr, of the Gay Men's Health Crisis in New York. Barr and a number of AIDS activists said that if Acer's patients were infected through his equipment, the medical community should focus on protecting patients from each other.

"What the AMA and ADA should be doing is calling on dentists and doctors to use universal precautions," Barr said. "They've taken the worst-case interpretation of this. It's really very irresponsible."

Jaffe said that even if Acer did directly infect his patients, the general risk of doctor or dentist to patient transmission is so slight that he did not think there would be any more than "a few other" similar cases nationwide. Some AIDS activists said that this made a general prohibition against HIV infection practitioners unjustified.