Seventeen women entered Judge Anthony M. Mariani's courtroom, took an oath and described sexual assaults they said came at the hands of South Hills oral surgeon Dr. Robert J. Boyda Jr.

Judge Mariani, presiding over the nonjury trial that began in April and proceeded in fits and starts, said yesterday that he found their accounts to be "compelling and disturbing," and that the women truly believed they were assaulted.

But those women were all under the influence of powerful narcotics designed "to take away memory and take away perception," the judge said.

So Judge Mariani acquitted Dr. Boyda of all charges because, in his eyes, the weight of 17 accusations stacked atop each other was not enough to overcome their flaws.

The words "not guilty" unleashed a torrent of emotion in the courtroom, packed with more than 100 spectators. The friends and family seated behind Dr. Boyda applauded wildly, while the accusers and their supporters behind the prosecution table wept loudly.

The standing-room-only crowd spilled into the hallway -- as nearly a dozen sheriff's deputies worked to keep the opposing groups apart -- with Dr. Boyda embracing one person after the next. He left without comment to the news media; coverage of the initial assault charges helped spark additional complaints.

In January 2008, Dr. Boyda, 44, of Mt. Lebanon, was charged after three women came forward to say they had been sexually assaulted while recovering from a procedure.

Once the charges were publicized, more women came forward. Some of the claims were cut out due to evidence rules, leaving 17 to testify against the Harvard-educated father of three at trial.

The large number of accusers made for an extraordinary case, as did the fact that Judge Mariani took a field trip one day to tour Dr. Boyda's Scott office, one of two in which the women claimed sexual assaults (the other was in Robinson).

The case took another twist last month when Judge Mariani revealed that he had been sent a letter claiming to be from more than 500 former dental and post-graduate students at Northwestern University, where Dr. Boyda attended dental school.

Judge Mariani said the letter -- which claimed Dr. Boyda had a habit of similar behavior years ago, and said "the group" would have a beef with the judge if the doctor were to be acquitted -- appeared to be a threat, and he offered to recuse himself. Deputy District Attorney Janet Necessary and defense attorney William H. Difenderfer declined the offer.

That set the stage for yesterday's ruling, in which Judge Mariani spent half an hour rehashing the case and explaining his decision. He said defense expert testimony raised significant doubts because the women were on a cocktail of powerful drugs -- including propofol, which has been known in rare cases to cause sexual hallucinations.

One of the defense experts, Dr. Edward Dench Jr., an anesthesiologist and past president of the Pennsylvania Medical Society, testified that the scenarios described, in which the women awoke to the assaults then lapsed back into unconsciousness, are not plausible. He said memory does not come and go under sedation, and a traumatic event such as an assault would jar someone awake.

After the verdict, supporters embraced Dr. Boyda with a single refrain: "It's over."

But the legal fight may yet continue.

Two of the accusers took steps toward filing a civil suit and still could proceed with their case. (The Post-Gazette does not name victims or accusers in sexual assault cases.)

Judge Mariani said he might have ruled differently if this were a civil lawsuit, since the burden of proof is a preponderance of the evidence in civil court -- not guilt beyond a reasonable doubt.

The attorney for the two women did not return a message seeking comment yesterday. They and the others who had said Dr. Boyda assaulted them could not be reached yesterday.

Regardless of the civil outcome, Dr. Boyda plans to resume his practice, Mr. Difenderfer said.

His license has been under suspension since the charges were first filed in January 2008. Because he was acquitted, Dr. Boyda can petition the State Board of Dentistry to reinstate his license, according to a spokesman for the Department of State.

When he does, Dr. Boyda plans to videotape all procedures.

"He will be undertaking precautions to alleviate anybody's concern," Mr. Difenderfer said.

Count Mike Silverman among the unconcerned. Mr. Silverman, 45, of Mt. Lebanon, said he's known Dr. Boyda for several years because their sons are friends, and he never believed the charges.

Mr. Silverman said he was among the numerous Mt. Lebanon supporters who sat in on the trial and traded e-mails throughout the case. They encouraged friends to pack the courtroom, and Dr. Boyda often had dozens of people sitting behind him during testimony.

The fact that the community didn't distance itself because of the scandalous charges -- and news media attention -- was a testament to a good friend, neighbor and youth sports coach, Mr. Silverman said.

"I don't know how he's endured as long as he has and kept his discipline and composure," Mr. Silverman said. "There is justice, if you can just wait for it."