The Oral Health Foundation has warned that callers to its helpline have been targeted by fraudsters who trick them into calling a premium rate phone number.
People seeking advice from the Dental Helpline, which is run by the charity, are been directed to call an expensive premium rate numbers by web pages set up by scammers.
The charity is still investigating the incident and has urged anyone affected to get in touch.
It said the helpline should only be called from its local-rate Rugby telephone number: 01788 539 780.
Dr Nigel Carter, chief executive of the Oral Health Foundation, said: “We are aware of a telephone scam in which a series of fake numbers, claiming to be the Dental Helpline, are taking money for unsuspecting callers.
“To clarify, our Dental Helpline has one telephone number only. This is a local-rate number (01788 539 780) and is not a premium line.
“If you have been passed any other telephone number, we ask that you please discard it and share this information with us.
“The welfare of those who reach out to our Dental Helpline is really important to us. It is always best to check the validity of a helpline number before calling or signposting people towards it.
“This is especially true if it is about a person’s health. In this case, their financial safety might be at risk too.”