There have so far been no reported cases of patients being infected by a batch of dental instruments which were not fully sterilised, the National Dental Centre Singapore (NDCS) has said.
It also said that it has added another layer of checks to ensure this does not happen again, even as it carries out a review of the incident and processes involved.
Last Monday, the centre discovered that a number of its instruments had not gone through a third and final sterilisation step, which destroys bacterial spores using steam.
Dentists at the centre used 72 packs of these instruments on some of the 714 patients who were treated there last Monday and Tuesday.
By 10pm on Tuesday, NDCS had contacted more than 685 of these patients.
NDCS' director, Dr Poon Choy Yoke, told The Straits Times that the centre has invited concerned patients to consult its doctors about risks arising from the incident and health screening options. NDCS will bear the costs of tests where appropriate.
"We have implemented additional controls in the meantime, which include having two staff confirm and verify that the sterilisation cycle is completed," she said.
We have implemented additional controls in the meantime, which include having two staff confirm and verify that the sterilisation cycle is completed.
DR POON CHOY YOKE, director of National Dental Centre Singapore.
Previously, the verification was done by only one staff member.
Private dental clinics contacted said they follow internationally recognised protocols when sterilising dental instruments. Their processes generally consist of three steps, similar to the NDCS' sterilisation cycle.
First, the instruments are physically washed to remove debris and tissue remnants.
Second, they are soaked in a cold sterilisation solution, which kills micro-organisms.
The last step involves wrapping the instruments in a pouch, before putting them into a machine which uses steam and pressure to kill any remaining microorganisms.
Said Dr Raymond Ang, chief operating officer of Q&M Dental Group: "It is of vital importance to sterilise dental instruments because we want to... prevent cross infection between patients."
Dr Anthony Tay, a dentist at The Dental Gallery, said the sterilisation process at his clinic takes about 45 minutes to 11/2 hours. He added that staff will check a tape on the pouch, which changes colour when the last step is completed.
Meanwhile, a spokesman for Raffles Dental said it conducts tests to ensure the proper functioning of the sterilisation equipment.
The Ministry of Health (MOH) said it audits the sterilisation processes of equipment during the regular licensing inspections of healthcare institutions to ensure they comply with MOH's regulations and guidelines. It also carries out random audits and inspections.
The ministry said it may conduct other checks on NDCS' processes and systems, before determining whether to take any regulatory actions against it.
There have not been similar incidents reported by public healthcare institutions to the ministry over the last five years, MOH added.
Dr Poon said NDCS' three-step sterilisation process of dental instruments adheres to hospital standards and has been in practice since the centre was established in 1997.