Children's teeth are being damaged by 'healthy' fruit juices, a dentists' group has warned.

Organic juices which combine sugar and fruit are the worst culprits for eroding the teeth, say the dentists.

Half of UK parents are unaware that they can contain as much sugar as some fizzy drinks, a YouGov survey reveals.

Dr Philip Stemmer, a dentist at Teeth For Life, advised parents to restrict children to one glass of fruit juice or full-sugar cordial a day.

Dr Stemmer said: 'Dental erosion caused by acidic fruit juices and squashes affects the whole surface of a tooth. Exposure daily will cause a progressive loss of enamel with the effect that the teeth 'shrink' and crumble at the biting edge.

'Even diet drinks which have no sugar in are very acidic and can dissolve tooth enamel.

'While mothers and fathers think they are doing the best by their children by giving them 'healthier' drinks, the acid in these drinks are wearing away the enamel.

'I am seeing more and more children whose teeth have been damaged in this way.'

He advised parents to try and combine acidic drinks with meal times and give the child a straw to drink soft drinks through.

Parents should also supervise teeth brushing to ensure it is thorough and use a toothpaste which contains fluoride.

And wait at least 30 minutes after drinking sugary or acidic drinks to brush because the teeth will have been softened by the sugar and you will brush away the tooth itself.

Dr Gordon Watkins, member of the British Dental Association's health and science committee, said: 'It's very difficult for parents. Fruit juices generally speaking are acidic and contain a considerable amount of sugar.

'The safest drinks out there are water and milk. If you have got to use fruit juice to get enough fluid into your kids, dilute it as much as you can with water.'

He said dried fruit was also bad for teeth.

'So many parents buy these healthy snacks of dried fruit but drying it concentrates the sugar so much it's almost like giving your child a jelly bean.

'Like everything, it must be eaten in moderation and it's better to eat it as part of a meal rather than as a snack.'

Recent research by YouGov found that 34 per cent of the UK's 10,513,700 children aged 4-17 drink at least two or three glasses of squash or cordial a day in winter. This could increase to an average of eight or nine glasses a day during the summer months.

Of the parents interviewed for the survey, over a quarter said their children drink absolutely no milk in their daily consumption of 10 beverages a day.

Milk in the diet helps the formation of strong teeth and bones and guards against osteoporosis. One glass contains a child's entire calcium requirement.