“It’s absolute bunkum,” she said. “We are one of the only fully private dental practices in Stratford and we only charge £25 for a check-up.

“We don’t know where they are getting their prices from but maybe they are combining the price for a check-up with that of a scale and polish. Even for a new customer when we spend more time with the patient the cost is only £40.

“Everyone is trying to be competitive. If you out-price yourself then you aren’t going to get the business.”

The website looked at the charges of 11,000 private dentists before compiling the report.

Caelen King, chief executive of whatclinic.com, said: “Even something as straightforward as a dental check-up can fluctuate by around £50 depending on where you live.

“If the whole family has regular check-ups every six months, as recommended, then the accumulated costs over time could be quite significant.

“It’s also worth checking prices in your local area, as we found the cost of dental treatments can also vary quite dramatically between dental clinics in the same city or town.

“Just spending a few minutes online comparing local prices could save you a considerable amount of money over the course of a year.”