David Howarth has 11 teeth and they're all loose — but he can't find an NHS dentist to give him an examination. Nor can John Kelf, who has resorted to doing his own fillings with a DIY kit from Boots. Which is why they have both been queuing in the rain outside the Langley Dental Practice in Manchester since 5am. The practice advertised that it has a limited number of spaces for new NHS patients, and the queue now stretches over the horizon to Bury.

It hurts Richard Hyland to queue. He is over 80 and has had both knees replaced. It also hurts him because he's an ex-navy man who believed he fought the second world war for a brighter future. Now here he is with one tooth broken off in his gum and no dentist to examine him.

"I paid my stamps," he says. "But why? What did I fight for? If I had my time again, I'd have turned round in 1940 and said, 'I'm not going.'"

The shortage of dentists in the NHS is getting worse. A heavily pregnant woman in Wrexham was unable to find an NHS dentist to deal with her severe toothache. So she rang NHS Direct, which told her the nearest dentist who could register her was 48 miles away. She ended up in A&E with a tooth infection which, had it been left untreated, could have harmed her and her unborn baby. Those American jokes about the state of Britain's teeth aren't so funny any more.

You wouldn't know it, but the government is in the midst of the most radical reform of dentistry since the NHS was founded. And by April 2006, that reform will be complete.

It will mean a new system of dental charges and a new NHS contract for dentists. It's designed to remove dentists from what they call the drill-and-fill treadmill by paying them for the overall service they provide to a patient, rather than for each individual treatment they carry out. At least, that's the idea.

Dentists aren't convinced. They reckon the charges will mean most patients will end up paying more. And that the new contract will put them on a different sort of treadmill. "It sounds glib," says Ian Wylie, the chief executive of the British Dental Association ( BDA), "but this could be the last chance to save NHS dentistry. Unless the government restores dentists' faith in the NHS, you could see a time where they no longer want to work for the health service."

There is already a shortage of NHS dentists. When a practice opened this year in Ludlow, the local primary care trust (PCT) refused to give out its address or phone number for fear of being inundated with clients. It feared similar queues to the ones in Wooton-under-Edge and Scarborough. When the BDA saw the queues in Carmarthen, after a practice said it was taking on more NHS patients, it said the situation "evoked a Third World country, where you have to queue to access what should be part of NHS care".

Tony Blair made the mistake of pledging, in 1999, that within two years everyone would have access to an NHS dentist. It didn't happen. The shortfall of dentists is getting worse. According to the Department of Health, it will more than double in the next five years. In Sweden there is one dentist for every 800 people. In the UK there is one for every 2,300 people and over 40% of dentists are refusing to take on new NHS patients. According to a Which? survey, the worst places to live are Cornwall, Shropshire and the Grampians, where it's nearer 75%. In parts of Wales your only chance of getting on an NHS dentist's books is when someone dies.

Most shaming for Labour are the statistics that reveal a widening gap in the levels of decay in children's teeth between the poorest and richest parts of Britain. In places such as Merthyr in Wales and Argyll and Clyde in Scotland, for instance, tooth decay is getting worse. In Barnsley, decay in five-year-olds is one tooth per child worse than it was seven years ago. Given that 4 out of 10 children aren't registered with a dentist, that should hardly be a surprise.

At the moment, dentists are allowed to choose how much private work they do. For many, their only commitment to the NHS is to those exempt from dental charges, such as children. The new contract will take away that freedom, and NHS dentists will be obliged to see everyone. The BDA says children are bound to suffer. Last year the National Audit Office found that spending on the NHS had increased by 75% since 1990-91, but spending on NHS dentistry had risen by 9%. But the government presents a different set of figures. "We've invested an extra £368m in improving NHS dentistry," says the health minister Rosie Winterton. "There are 170 extra places at our dental schools and we've recruited the equivalent of 1,000 new dentists." Although that doesn't take into account the total number of dentists leaving the NHS.

It's no wonder people are going abroad for "dental holidays". Alan Scott-Barrs and his wife, Yasmin, both needed urgent dental work but couldn't get it done on the NHS. He needed caps and root fillings, but was told — at 75 — he was too old for anything other than a new set of dentures, which he didn't need. And she faced up to a year's wait. The private cost of the work in the UK would have been £18,000. On a dental holiday in Poland they paid £4,800.

The government has picked up on the idea and is bringing in dentists from overseas. There are, for instance, 117 Polish dentists in the NHS. "But the level of treatment they offer is limited," says Ian Mills, who runs a dental practice in Devon. "They're not general dental practitioners, and are more inclined to hand things on to a specialist. It takes a long time for them to be acclimatised. Then they're going back home."