Queensland dental patients caught up in a sterilisation bungle have returned negative results for blood-borne viruses.

The results for the last patient to be tested are expected on Friday.

Thirty-three patients were treated at Bundaberg Hospital's dental health clinic on November 6, the day a problem occurred in the cleaning process for dental instruments.

Two were not treated with instruments, but Queensland Health tested the remaining 31 patients for Hepatitis A, B and C and HIV.

The tests were done to determine whether any of them might have passed on an infectious viral disease to any one of 235 patients treated the following week.

Queensland Health initially said the 31 patients visited the clinic "prior" to the bungle occurring.

However, on Wednesday, they admitted some of the 31 patients may have also been operated on with unclean instruments, as it was believed the cleaning mishap occurred at about 10am (AEST) on November 6.

Queensland Health director-general Mick Reid said the issue had been complex, but admitted his department should have been more clear in communication.

"While we are confident there is a very minimal risk to patients, we know this is a difficult time for them," Mr Reid said.

He said he would be placing the highest importance on getting to the bottom of what occurred.

"What occurred was not good enough and I apologise for any confusion and distress caused by this episode," he said.

Queensland's chief dental officer has been appointed to assume operational control of the oral health services for the region until the issue and investigation into the issue has been resolved.

"I hope that this action will go some way to restoring the community's confidence in the services provided by the Bundaberg oral health service," Mr Reid said.

Queensland Health said they were providing free counselling and all the blood testing was free.

However, Liberal National Party (LNP) MP for Burnett Rob Messenger said the government should also offer financial support to those left out-of-pocket by the error.

One patient treated on November 6, Gabrielle Carruthers, was informed she may have contracted HIV and quit her job in the hospitality industry in case she had contracted a disease.

Mr Messenger said the 16-year-old, who lives independently, was just one person the government had an obligation to help.