Fillings - How much do you pay?

Belfast - �28 to �40 Cornwall - �38 to �45 Croydon - �35 to �50 Edinburgh - �35 to �55 North-east England - �29 to �45 North-east Scotland -�28 to �43 Newport - �24 to �36 Yorkshire - �25 to �45

The NHS has fixed charges for a variety of the most common dental treatments - for example, a simple check-up including scale and polish is �13.20.

However, typical private charges range from �30 to �40, and more than one in 10 dentists quoted more than �50.

The most quoted was �88.50 for the quick clean-up - and one in four dentists in Edinburgh charged more than �50 for the pleasure.

The investigators also found that many dentists were unwilling to spell out in advance exactly what each procedure was likely to cost.

In all, Which? looked at more than 200 dentists from Belfast, Cornwall, Croydon, Edinburgh, Newport, north-east England, north-east Scotland and Yorkshire.

Dentists in rural as well as urban areas were included in the survey.

Helen Parker, the magazine's editor, said that the price variations were "startling".

She said: "As with all goods and services it's impossible to tell whether or not you're getting value for money unless you can compare prices.

"We'd like to see all dentists publishing price lists. If you pay for private dental treatment, check out your dentists' charges against other dentists in your area."

Gold crown

The NHS guide price for a gold crown is �70.72, but many private dentists charge significantly more than this - typically between �175 and �250.

However, 22 dentists charged between �300 and �400, and four between �400 and �500.

Only eight charged less than �125 for the procedure.

Edinburgh turned out to be one of the most expensive places to get this done.

Similarly, customers may be paying far more for their fillings if they go private.

The NHS might typically charge a patient �11 for a large filling, and typically, private charges were between �30 and �45, although some charged as much as �90.

In each geographical area tested, there were dentists who offered a cheaper private service, with 30 in all charging less than �23.

It is not entirely clear exactly how much money dentists earn inside and outside the NHS.

The Department of Health says that a full-time dentist working entirely for the NHS should earn between �55,000 and �65,000.

One study suggests that dentists mainly in private practice can earn as much as twice this.

There is a nationwide shortage of NHS dentists, and on Wednesday, the government unveiled more measures to tackle this with a �1m investment in women's dentistry.

Women who need flexible working environments often find it difficult to earn a reasonable wage from NHS work.

The money is aimed at attracting women dentists back to the profession after they have taken a career break.