Call it the Anbesol defense.

A Penobscot County jury on Thursday acquitted a South Portland man of operating a motor vehicle while under the influence of intoxicating liquor after he claimed that he had used the over-the-counter toothache reliever about 20 minutes before taking a breath test.

Michael W. Tatarcyk, 26, was arrested Oct. 8 on Wilson Street, Brewer, by an officer who said his car was weaving within its own travel lane. The breath test indicated that his blood-alcohol content was above the legal threshold of 0.08.

Whether he told Officer Danny Costain, who arrested him, that he was using the medication was in dispute.

But what his attorney, Ann M. Murray, brought out during the three-day trial before Justice Eugene Beaulieu was that Tatarcyk had had his wisdom teeth out two weeks earlier and was applying the Anbesol — which she said was 70-percent alcohol — directly to the healing tooth socket to deaden the pain.

“He’d been using it over the course of the day and had just poured some on,” Murray said after the verdict came back. Tatarcyk’s was the first criminal case she had tried since she left the district attorney’s office in October 1988 to work in private law practice.

The prosecutor — Murray’s former colleague, Gregory Campbell — concurred with the results of experiments that showed that, in high enough dosages, Anbesol could affect the results of a breath test. But the prosecution questioned whether Tatarcyk’s dose had approached the necessary level.

Campbell said he saw the acquittal as “an isolated incident” rather than evidence of a trend.

“I don’t think people will be running out buying Anbesol (seeking similar results),” he said.