Health authorities are urging more than 500 patients of a dental clinic in Far North Queensland to be tested for HIV and hepatitis.
The Essential Dental for Life clinic at Smithfield in Cairns has been temporarily closed as its infection control practices from March 2018 are investigated.
The clinic has about 550 people on its books.
Don Mackie from the Cairns and Hinterland Hospital and Health Service said patients had been exposed to a low risk of several diseases, including HIV and hepatitis C.
"It's about the cleaning and sterilisation of instruments between one patient and the next," Dr Mackie said.
"There are standard processes and we are led to find that these were not being done in the standard and acceptable way."
Dr Mackie said it had "no evidence that anyone has gotten any infections because of this".
"But we're going through the screening process really out of an abundance of caution, to make sure people are identified and given very effective treatments for all of those conditions, which can often go on for a while undiagnosed without proper screening.
"It's really just standard infection control — particularly around the autoclaving and sterilising of instruments."
Practice 'very cooperative'
Dr Mackie said there was "a very remote possibility" of someone getting HIV.
"It's … really comes down to the use of the autoclave and all of those other processes," he said.
"That raises the very low probability that some patients may be at risk of blood-borne infections."
Dr Mackie said a free screening clinic would be established to help patients.
"It's taken us quite a bit of time to actually establish the risk that's presented and … to work through the list of patients," he said.
"Now I've got to say, the practice has been very cooperative in helping us with this."
'Trust is blown to pieces'
The owner of the clinic, dentist Ken Hossen, said it had been "very upsetting".
"People that I've loved and cared for 30 years now think I've given them some kind of blood-borne virus and the reality is the chances of me doing that are actually miniscule," Dr Hossen said.
"I just don't know what they're going think I am now — they're going think I'm some kind of monster, and I'm so sorry to them and I apologise that this has happened.
"They put their trust in me and now … that trust is blown to pieces."
The clinic's website said Dr Hossen had provided dental treatment at Smithfield since 1993.
Dr Hossen said at the end of May he was told someone had made a complaint.
"I've been shut for most of June and July," he said.
"I complied in every way I could — I have nothing to hide, nothing."
Dr Hossen said health authorities had started a "fear campaign".
"It's been really terrible — it's like having some bullies come into your workplace and they [health authorities] make threats, and I've tried my best to comply with these people," he said.
"They [health authorities] have absolutely no evidence that I've harmed a soul — none whatsoever. They have no evidence I wasn't sterilising things properly either.
"The fear campaign they've now started with this media release is shocking — I've told them that surely there's better ways of handling these things?
"To put it on social media and then to put a media release, you think why are they doing it this way?"
