Six Sydney dentists have been suspended over poor hygiene control that may have exposed up to 12,000 patients to HIV and hepatitis.

NSW Health is recommending people who had invasive procedures at the Gentle Dentist in Campsie and Sussex St or the Surry Hills and Bondi Junction surgeries of Dr Robert Starkenburg be tested for blood-borne diseases.

Gentle Dentist operator Dr Samson Chan, four of his staff and Dr Starkenburg have all been suspended following investigations prompted by customer complaints.

"There is an array of problems, including the cleaning of instruments, functioning of sterilisers, the knowledge of the practitioners and recording of the results of the sterilising equipment," Dr Jeremy McAnulty, director, Health Protection at NSW Health told reporters in Sydney on Thursday.

Another six dentists from the Gentle Dentist have had conditions placed on their licences.

The Gentle Dentist clinic.

Remaining staff at the Gentle Dentist have kept the practices open, while Mr Starkenburg's surgeries have been closed.

There is no evidence an infection or transmission has occured, however patients of those dentists who underwent invasive procedures are advised to visit their GP to be tested for HIV, hepatits B and hepatits C.

The risk to public health has been deemed low.

NSW Health is contacting patients who may be affected.

Nearly 11,000 could be at risk of HIV and hepatitis. (AAP/file) (AAP/file)

For more information call The Australian Dental Association NSW Helpline on 1800 610 344.

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