Public Health England (PHE) said parents were dropping children off at nurseries with teeth un-brushed, and give them baby bottles and sipping cups filled with sugary drinks.
The neglect is causing up to one in three primary age kids - and 12 per cent of three-year-olds - to suffer 'rampant' levels of aggressive decay resulting in too many children being forced to go through 'harrowing' dental extractions involving a general anaesthetic.
Dr Sandra White, PHE director of dental public health, said: "This is preventable, it doesn't need to happen - we should be ashamed of ourselves as a nation."
Dr White said many parents were giving babies and toddlers fruit juices without realising they were packed with sugar.
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She advised parents to only give milk or water to children until the age of three, and avoid using bottles or sipping cups for any drinks which contain sugar.
Dr White said fruit juice was now 'the biggest culprit' behind shocking levels of decay in many parts of the country.
The senior dentist said: "Fruit juices appear healthy but actually have a lot of sugar – parents are just trying to do their best for children but don't realise how much sugar there is in the fruit drinks."
In other cases, toddlers were being given squash drinks at a dangerously young age.
Dr White said: "You find parents putting squashes into baby bottles - children who are hardly out of nappies with a bottle of sugary drink in their mouth.
"With mothers and fathers often at work all day, you get busy parents dropping kids off at nursery and running, and they haven't brushed their teeth, so this isn't just a job for parents - it's for nurseries and for grandparents, and carers."
Dr White said she sympathised with parents who gave infants sipping cups, in a bid to reduce spillages.
She said: "I know it is difficult with toddlers, I had it with my own kids, you give them a drink in an open cup and with one shake it is everywhere.
"The worst thing is going to bed with any kind of sugary drink in a bottle."
Officials said the data on three-year-olds suggested widespread problems across society, with problems in affluent as well as deprived areas.
Dr White suggested many families who prided themselves on only buying organic fruit juices did not realise the sugar content was still dangerously high.
She said: "Organic apple juice sounds really healthy on the packet but actually it's packed with sugar. Posh sugar is no better than any other sugar."
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