TULSA, OK - Former patients of a Tulsa, Oklahoma dentist are being told to get tested for HIV after the state's dental board exposed unsanitary conditions inside his offices.

7,000 patients are receiving a letter warning them they may have been exposed to Hepatitis C, Hepatitis B and even the virus that causes AIDS because of unsanitary conditions inside two dental offices.

State health officials discovered the problems after one of Dr. Scott Harrington's patients tested positive for Hepatitis C. The patient's only known risk factor for acquiring it was dental treatment.

"We've never had a complaint of this nature or this type," says Susan Rogers, executive director of the Oklahoma State Board of Dentistry.

A 17-page complaint from the Oklahoma Board of Dentistry calls Doctor Harrington a "menace to the public health."

Investigators found rusty medical instruments, bleach used to sanitize dental tools, open vials of drugs and exposed needles...all potential risks for contamination of patients.

The office's medical sterilization machine was supposed to be tested every six months, but investigators found "no such test had ever been performed in the six years one dental assistant had been working at the office."

Officials say Harrington seemed to pass the blame during interviews.

His assistants may have also committed felonies at the practice by performing IV sedation on patients without a license.

Investigators say patients treated as far back as 2007 may have been exposed and are offering free testing to all of Harrington's patients.