St. Louis • An independent panel investigating how hundreds of veterans may have been exposed to viruses from dental work performed at the St. Louis VA medical center is expected to complete its work in 60 days.

The three-member Administrative Investigation Board will interview witnesses and conduct a complete review to determine the reasons for the failure to follow correct procedures. The panel also will make recommendations to prevent another occurrence.

William C. Schoenhard, deputy undersecretary for Health for Operations and Management, discussed the review Tuesday after he toured John A. Cochran Medical Center and met privately with hospital staff and patients.

Although the Department of Veterans Affairs has "a very good sense of what occurred," Schoenhard declined to assign blame until the review is completed.

Last week, the VA sent letters to 1,812 veterans warning that they might have been infected from improperly cleaned dental equipment at Cochran. The warning touched off an outcry, prompted congressional scrutiny and led to the chief of the dental clinic being placed on leave.

During a press conference after his tour, Schoenhard lauded the hospital staff's vigorous response once they learned of the problem, calling them "dedicated and compassionate."

"They took seriously their duty to serve those who have served our nation," he said.

Schoenhard also said he apologized to patients and their families and told them the VA was doing everything it could to assure they received the best possible care.

He said the patients were grateful the VA had contacted them, understood that mistakes can be made and were appreciative of the care they were receiving.

The breakdown at Cochran, according to the VA, happened during the prewash of dental instruments. A detergent is supposed to be used during the washing process, before an instrument such as a dental pick is put into a sterilizer. The instruments were rinsed, but no cleanser was used.

The instruments, though, did go through heat sterilization, which is thought to kill all microorganisms, including the viruses in question. The lapse was discovered in March in a routine inspection by an infection control team. The VA needed time to review the information, identify patients and study the scope of the problem before it could notify veterans, officials said.

The hospital is offering free blood testing to screen for the hepatitis B virus, the hepatitis C virus and for HIV (human immunodeficiency virus) infection. So far, 480 veterans have responded. Hospital officials said they expect to notify patients of test results in two weeks.

Schoenhard reiterated that the chance of infection was "very, very low."

Even so, the VA implemented a nationwide policy this week that makes supply processing departments responsible for cleaning all dental instruments. In the past, it was left up to individual hospitals whether equipment was cleaned by the processing department or the dental clinic. At Cochran, pre-cleaning of the instruments was done in the dental clinic.

Dr. Patricia Arola, assistant undersecretary for health for dentistry, said she toured Cochran's processing department Tuesday and called it 'state of the art with energetic employees."

"I have great confidence in the supply processing department," she said.

But just recently at Cochran, the cleaning of endoscopes was moved from the supply processing department to the gastrointestinal unit after problems surfaced with equipment not being properly cleaned.

Hospital leaders closed the department for two weeks in December and January to train staff and to sterilize all endoscopes, which are used in colonoscopies and other procedures.

A month later, after receiving a complaint about endoscope sterilization, Veterans Affairs inspectors visited the hospital and found several health and safety infractions. The temperature in the sterilization area was too high, rags and gloves were 'strewn about" in the decontamination areas, filters had not been changed as required, a technician was not wearing protective gear, chemical test strips were left exposed, emergency exits were blocked, and employees were unsure whether an unattended endoscope was sterile, according to an inspection report issued in April by the VA's Office of Inspector General.

Arola said she was unfamiliar with those problems.

The House Committee on Veterans' Affairs is launching an investigation into the problems at Cochran and has scheduled a hearing for Tuesday in St. Louis.