Tooth decay among children is at its lowest recorded level since 1983, figures show.
Many children brush twice a day
The biggest fall was among 15-year-olds, with only 13% suffering from decay compared with 42% in 1983 the Office for National Statistics found.
But the survey discovered variations across the UK, with Northern Ireland having the highest level of tooth decay among children.
The lowest levels were found in England, followed by Wales.
A reason to smile?
The survey looked at the dental health of 10,381 children aged five, eight, 12 and 15.
The inequalities appeared to be partly linked to the type of school a child attended as well as where they lived in the UK.
The survey found 78% of eight-year-olds from "deprived" schools had plaque compared with 70% of "non-deprived" schools.
But three-quarters of children in all age groups reported brushing their teeth twice daily, with many using electric toothbrushes.
Almost half of 15-year-olds are using mouthwash and sugar-free chewing gum.
Despite the apparent fall in levels of decay in permanent teeth, more children had plaque and gum disease - particularly the boys.
About 68% of 15-year-old boys had some plaque, compared to 57% of 15-year-old girls, and 56% of 15-year-old boys had some gingivitis, compared
to 48% of girls.
And more children are now having fillings.
Among eight-year-olds, 52% of obviously decayed permanent teeth had been filled, compared to only 37% 10 years earlier.
The survey found that most parents would prefer their children's decayed permanent teeth to be filled.
But the majority of parents would prefer their children's "milk teeth" to be removed rather than filled.
Among children aged five, over half had evidence of some early damage to their teeth.
The British Dental Association said while it was pleased decay was down it was concerned about the gap between those who experience the best and worst dental health.
Professor Liz Kay, scientific adviser to the BDA, said:
"While this report does demonstrate a welcome overall improvement in children's dental health, the gulf between those with the best and worst oral health persists.
"This report shows that a high percentage of our children still suffer unacceptable levels of tooth decay."
She said targeted water fluoridation would be a simple, safe and effective way of helping to reduce tooth decay.
But Peter Crampton of the National Pure Water Association said fluoridation was not the answer.
"What is required is education of children and parents through schools, adequate preventative dental provision and the provision of healthy nutricious meals in school and at home.
"We need to move away from high sugar and high calorie intake.
"In taking this action it would address tooth decay, childhood obesity and diabetes," he said.