More than half of students in some schools for migrant children have decayed teeth, according to a program launched by the Shanghai branch of Roots & Shoots, an international non-governmental organization promoting environmental education and action.

Working with Shanghai Ren'ai Hospital, the NGO visited seven schools in Shanghai to conduct a dental health survey and education.

Doctors said 51 percent of students in the schools have decayed teeth, mostly because their parents lack knowledge about proper dental care.

The study found that less than 20 percent of children in the schools brush their teeth twice a day.

"Proper teeth brushing is the best way to prevent tooth decay, while many parents don't realize how important it is," said Dr Tao Suxiong, director of Ren'ai Hospital's department of stomatology. "We will launch lectures to teach parents and students how to take better care of their teeth."