CHICAGO, March 28 – A dirty dentist placed 7,000 patients at risk of contracting HIV and other infectious diseases after failing to properly sterilize equipment at his Oklahoma practice, health officials warned Thursday.

Officials do not yet know if any patients were infected but urged everyone who had ever been treated at the Tulsa oral surgery practice to be tested at a free clinic.

"We do not know how long these improper practices have been occurring, so we recommend that all patients of Dr. (Scott) Harrington's be tested for Hepatitis B, Hepatitis C, and HIV," the Oklahoma health department said in a statement.

"It should be noted that transmission in this type of occupational setting is rare."

Inspectors discovered a host of problems with the Tulsa dental practice earlier this month and Harrington voluntarily shut his doors until the investigation is complete.

In addition to the rusty equipment, inspectors also found expired drugs – includeing a vial that should have been thrown out in 1993 – and a host of other violations, the Tulsa World reported.