An Oklahoma dentist has been discovered using unsanitary medical equipment — and nearly 7,000 patients are being urged to be tested because health officials fear they may have been exposed to infections.The patients of W. Scott Harrington in Tulsa have been urged to get tested for HIV, Hepatitis B, and Hepatitis C, Fox News reports.“This is an unprecedented event,” Susan Rogers, executive director of the state Board of Dentistry, told Fox. “To my knowledge, this has never happened before as far as a public notification of a (hepatitis C) case involving a dental office.”According to Fox, health officials found “major violations” of the Oklahoma Dental Act, as well as several violations of safety and health laws, while investigating Harrington’s practice.He had been practicing in the area for more than 30 years.The violations included employees using dirty equipment, reusing needles and administering drugs without a license.Harrington voluntarily closed his practice and is cooperating with investigators, Rogers told Fox. He faces a hearing before the state Dental Board on April 19. Harrington could lose his license.Letters are to be mailed on Friday to the 7,000 patients treated at Harrington's clinics in Tulsa and suburban Owasso since 2007.The patients are urged to get tested for hepatitis B, hepatitis C and HIV. Health officials said that it was rare for infections to spread in occupational settings but that tests were important, Fox reports.