April 19, 2013 -- Former patients of a Tulsa, Okla., dentist accused of using dirty needles and instruments are outraged over reports that at least 60 people have tested positive for hepatitis and HIV. But investigators say the source of the infections is still unclear.

More than 7,000 patients from W. Scott Harrington's Tulsa and Owasso clinics were sent letters in late March outlining the risk of infection from poor sterilization practices and steps to obtain free blood testing. Of 3,122 patients tested by county health departments so far, 57 tested positive for hepatitis C, three tested positive for hepatitis B, and at least one tested positive for HIV.

"I think everyone here in Tulsa is shocked that an oral maxillofacial surgeon was so absolutely sloppy in both his technique and his regard for patient safety," said Patrick Carr, an attorney representing one of Harrington's former patients. "It's extremely upsetting for everybody."

Carr's client, 38-year-old Christina Quin, had her wisdom teeth removed by Harrington in April 2009, according to a lawsuit filed in the District Court of Tulsa County. Days later, after increasing pain, she returned to the office with an infection and was prescribed antibiotics, according to the complaint. But the infection persisted, and Quin claims she developed a fever, rash and signs of liver problems.

Carr says Quin was not diagnosed with hepatitis or HIV, but "something else, and it made her very ill."

"We believe it was due to the improper sterilization techniques the dentist had employed," he said.

Quin, who declined to speak publicly through Carr, recovered from her infection, and at the time "had no reason to suspect that Dr. Harrington had acted in any way negligently or that any of his practices or omissions caused or contributed" to it, according to the complaint. But a March 28 report by the Oklahoma Board of Dentistry slamming Harrington for poor sterilization practices led her to sue for damages relating to "anxiety, fear, lack of trust, and difficulty sleeping due to thoughts of Dr. Harrington's acts and omissions."

"It's an absolute betrayal of trust," said Carr. "When people go to any doctor, they assume -- and rightly so -- that their health is the highest concern. She feels like she has absolutely been betrayed."

Carr said he's spoken to "a number" of other patients with similar concerns, but is unaware of legal action being taken by anyone other than Quin. He hopes her case will go to trial within the year.

The Tulsa and Oklahoma health departments are in the process of notifying Harrington's former patients of their blood test results. Patients who tested positive for hepatitis and HIV will be personally contacted, counseled about the disease and directed to resources for care, the agencies said in a statement. Testing may also be recommended for their spouses or partners.

"We understand these first reported test results may be of concern," Tulsa Health Department Director Dr. Bruce Dart said in a statement.

But state epidemiologist Dr. Kristy Bradley stressed that the source of the infections is still under investigation.

"The next phase will include more in-depth interviews of persons who test positive to determine the likelihood that their exposure is associated with their dental surgical procedure at the Harrington practice," she said in a statement. "We will certainly continue to keep the public informed as we learn more."

Such an investigation usually involves epidemiological studies assessing other risk factors for hepatitis and HIV, as well as laboratory studies comparing the genetic fingerprints of the viruses in different patients, according to experts at the U.S. Centers for Disease Control and Prevention.

Dentist Slammed for Poor Sterilization Practices

A surprise inspection of Harrington's practice on March 18, prompted by a patient's positive test for HIV and hepatitis C, revealed the use of old needles and rusty instruments, as well as the practice of pouring bleach on patients' wounds until they "turned white," according to the complaint filed by the Oklahoma Board of Dentistry.

"The basic things that everyone knows -- follow CDC guidelines, use clean syringes, don't reuse multi-dose vials in multiple patients, don't use rusted equipment -- those are things even non-physicians know," board president Susan Rogers told ABC News at the time. "Those are basic things. That part makes it egregious."

Instruments used for patients who were known to carry an infectious disease were given an extra dip in bleach on top of normal cleaning methods, according to the complaint. But the tools had red-brown rust spots, indicating that they were "porous and cannot be properly sterilized."

Harrington, who has been practicing for more than 30 years, voluntarily surrendered his state dental license and could face criminal charges. A license revocation hearing before the state dentistry board is set for Aug. 16.

The Tulsa Health Department has set up a hotline at (918) 595-4500 for people with questions.

ABC News' Dr. Richard Besser contributed to this story.