document: Thousands of children have been examined every 10 years since 1973.
  A third of children in Wales were said to have good oral health overall, which compares to 39% in England.
  Decay was found in 52% of 12 year olds and 63% of 15 year olds, a slight improvement on the 2003 survey.
  But around 70% of them reported problems with their teeth.
  Decay was found in 41% of five-year-old children in their primary teeth and in 55% of eight-year-old pupils, according to the Health and Social Care Information Centre report.
  Severe dental problems were worse among children from poorer backgrounds.
  Around a half (47%) of five year olds could be said to have good oral health.
  But that declined with age, to around a quarter of 15 year old children.
  Other findings:
  The last results in 2003 showed that oral health had improved greatly since the 1970s and 1980s.
  This time, 12 and 15-year-olds were also asked to fill in a questionnaire on how they looked after their teeth.
  In 2009 the Welsh government launched a national scheme to encourage better dental health amongst young children. Since then it has invested over Â£12m in the programme.
  It also suggested the programme had led to a recent  6% drop in the proportion of five-year-olds experiencing dental decay.
  Experts point out there could be several reason the health of children's teeth in Wales was still lagging behind those from other UK nations including socio-economic conditions.
  That survey 10 years ago also showed a big drop in 15-year-olds with obvious decay from 94% in 1983 to 58%.
  Scottish children are not included in the 2013 survey but Wales has better results than Northern Ireland, where 31% were judged to be in good oral health.
  The Welsh Government said its own most recent monitoring survey showed a 6% drop in the proportion of five-year-olds with dental decay.
  "However, there is more to do to improve the dental health of children in Wales especially since the vast majority of tooth decay is avoidable," said a spokesperson.
  "Parents can help their children by reducing sugar intake and encouraging them to brush their teeth twice a day with fluoride toothpaste. "
  It has also published its own survey of dental health to identify how much decay among five-years-olds is already present at the age of three.
summary: Only a third of children in Wales have healthy teeth overall and this is lagging behind England, a major survey suggests.