Some children treated needed several teeth extracted under general anaesthetic.
The Health and Social Care Information Centre said 1,235 under-twos needed hospital treatment, including 134 under one whose milk teeth would have only just emerged.
There were 45,259 admissions for under-18s for tooth decay – equal to 870 a week.
The numbers have increased by 10 per cent since 2010, which dentists blame on our increasingly sugary diets and less frequent check-ups.
Dentists say parents who give their kids fruit juice assume they are giving their children something healthy, when in fact sugar in the juice is eating away at their teeth.
She added: "Children are snacking more and these foods contain hidden sugar. People aren't always aware that fruit juice can cause just as much tooth decay as fizzy drinks.
"Parents are not taking their children to a dentist as early as they used to – they need to be taking them from birth."
Dr Sandra White, director of dental public health at Public Health England – the government agency responsible for preventing poor health, said: 'Tooth decay is a serious disease and can result in having teeth removed in hospital under general anaesthetic, which is stressful for the child and the parent."
A glass of apple juice contains seven teaspoons of sugar – the same as a can of coke. A smoothie also contains seven, a yoghurt four and a cereal bar four and a half.
More on Parentdish: Is fruit juice rotting your child's teeth?