Powerful lawmakers are drilling down into the Department of Veterans Affairs, seeking answers to how a Wisconsin dentist who treated vets was able to ignore safety and sanitary procedures, potentially exposing hundreds patients to HIV and hepatitis.

The patients were treated by a dentist at the Tomah, Wis., VA facility, where the unnamed dentist used improperly cleaned equipment. Acting Medical Director Victoria Brahm said last week 592 veterans who received care from the dentist can receive free screenings for Hepatitis B, Hepatitis C and HIV.

"I pray no one has an infection," Brahm said, adding that the risk is low.

On Tuesday, Sen. Ron Johnson, R-Wis., chairman of the Senate Homeland Security and Governmental Affairs Committee, and Sen. Chuck Grassley, R-Iowa, chairman of the Senate Judiciary Committee, fired off a letter to VA Secretary Robert McDonald demanding answers about the VA’s training procedures and equipment protocol as well as steps that the VA is taking to ensure safety.

“It is unclear what other steps the VA has done to hold [the dentist] accountable for the breach of protocol,” the letter stated. “Further, it is unclear what the VA is doing on a national scale to ensure that all VA doctors, not just dentists, comply with safety protocols.”

The dentist, who reportedly used, cleaned and reused his own equipment, in violation of VA regulations, was placed in an administrative role before resigning last week. His actions came to light when a whistle-blower came forward, and the Office of Inspector General recently opened a review of the situation.

In the letter, Johnson and Grassley sought explanations of the VA’s disposable equipment protocol, what punishment the dentist faces and what steps the agency intends to take on a national scale to ensure that all VA doctors comply with safety protocols.