Australian officials want up to 11,000 people to see their doctors for tests for HIV, hepatitis and other blood-borne diseases over fears of hygiene breaches and poor sterilisation procedures at Sydney dental clinics.
A New South Wales (NSW) Health spokesman said the at least 11,000 patients of two dentists were at "low risk" of having contracted disease but officials have begun to contact the patients.
"The issue is if a patient with a blood-borne virus attended one of these practices and the instruments used were not sterilised properly," he said.
"We are hopeful there won't be transmissions and the risk is thought to be low but it's best for people to know their status because there are treatments available for infections."
Dr Robert Starkenburg and Dr Samson Chan, who worked for the Gentle Dental clinics in Sydney, as well as four other dentists have been suspended from the medical registrar so far. Six dentists have had conditions placed on their licences.
Local media reported that 75-year-old Dr Starkenburg admitted hygiene practices may have been "lax at times" in his office.
"I don't infect my patients but I didn't have a spick and span office like the new guys. But I'm spikko now," Starkenburg told the Sydney Daily Telegraph.
The transmission of bloodborne diseases into the gums of patients is if instruments are not properly cleaned and sterilised.
More than 40,000 patients have been treated in the clinics under investigation in the last 10 years and Sydney officials say people who received invasive surgery are more likely to be at risk of having contracted HIV and hepatitis.