METHUEN — Three weeks after a controversial Board of Health vote to fluoridate the town’s drinking water — a vote that cost the health director his job and one board member her post — a new board reversed the decision last night.

The 20 or so people who filled the small, second-floor conference room of the Searles Building took the chance to argue the issue — sometimes emotionally — before the two new members of the board did as expected and rescinded the May 29 vote to fluoridate. Chairman Dr. Dante Santone, the only member left from the board that took the original vote, said in advance he had to work and was not at the meeting.

Jeanine Lorenzo filled his chairman’s role for the evening, and said after the meeting that while she is in favor of fluoridating the water, she joins the many town officials and fluoride opponents who were upset by the way the vote was taken.

“I don’t think three people should make that decision for the entire town,” said Lorenzo, an administrator at Saints Memorial Hospital in Lowell who replaced former member Paul Cardone earlier this month for reasons not related to the fluoride vote.

Many people, including Town Council members and Mayor Sharon M. Pollard, were angered to learn of the decision more than a week after it happened. They argue that since referendums in 1981 and 1997 rejected fluoridation, another referendum is the only appropriate way to approve it.

Health Department Director Dr. Robert Katz was forced to quit and board member Mary-Ruth Roby, whose term was up this month, was replaced last week by Joyce Hersey after refusing the mayor’s request to rescind the vote. Santone also refused, but can’t be replaced until his term ends in January.

Lorenzo insisted she wasn’t worried about the impression that the board — which is given independent decision-making power by the state — is under the influence of Pollard or other town officials. She’ll vote her conscience, she said, but having that power means the board should be more aware of others’ feelings, not less.

“Because of the autonomous nature of the board,” she said, “we have to be extra careful how we vote for anything.”

Fluoride is endorsed by the world’s medical and dental establishments as a way to fight tooth decay, and most Merrimack Valley towns started fluoridating the water decades ago. But opponents insist it violates their freedom of choice and can cause health problems.

Both sides were out to argue their side last night, including residents, several dentists and Town Councilor Michael E. Condon, all of whom opened the meeting with about 40 minutes of often-heated debate about the merits of fluoridation and the proper process for making a decision.

Fluoride supporters’ only chance now, however, is a repeat of 1997, when the Town Council put the issue on the ballot as a nonbinding referendum and the Board of Health agreed to abide by the results. Fluoride was rejected narrowly. Lorenzo said she is in favor of that process, and Town Council Chairman William M. Manzi III said if a majority of the board wanted it the council would consider it.

The only way the issue could become a binding referendum is if the Board of Health votes in favor of fluoridation and opponents gather enough signatures to get it on the ballot. Santone said that was the board’s hope from the start.