The report, by the Welsh Oral Health Information Unit, which is based at Cardiff University and Public Health Wales, shows that since 2004-05, the proportion of children who have no tooth decay has risen from 54.9% to 64.0% in 2012-13.
In 2013 in a class of 30 children, on average about 19 will have no decay in their permanent teeth compared with 16 in 2004.
Health minister, Mark Drakeford, said: ‘This report shows a very welcome reduction in the number of 12-year-old children in Wales with tooth decay.
‘It is encouraging that more children have no obvious decay experience in their permanent teeth by the age of 12.
‘It is a significant achievement that we have managed to halve the prevalence of what is a chronic disease over the last 25 years.
‘Our Designed to Smile programme has been working with younger children; we hope its effects will be seen in future surveys and will have had a positive impact in speeding up improvements in the oral health of children living in some of our more deprived communities.’
There is still a strong relationship between dental decay and deprivation.
However, this latest survey shows signs of a faster improving position for children in the most deprived communities.
This reduction in dental decay in children continues the trend of marked improvement in oral health over the last 25 years, which has seen the average prevalence of decay reduce by more than half.