HALF the Chinese population has tooth caries, according to an investigation by the National Committee of Oral Health (NCOH).

For children under five, the rate is as high as 77 per cent, with five decayed teeth on each child.

"Tooth caries have been decreasing over the past few years," said Zhang Boxue, a dentist of the Oral Hospital attached to Beijing University. "But there has been an obvious gap among different regions of China.

The condition is comparatively good in Beijing, Shanghai, and Shandong, Zhang said, "Each child has less than one bad tooth on average."

But in provinces such as Guangdong, where people prefer sweet food, and North eastern provinces like Liaoning where the drinking water contained too little fluoride - useful in preventing caries, the problem remains at a high level.

There are effective methods against tooth caries, which are related to life habits rather than medical practice.

"Dental health is more of a social issue rather than just a medical issue," Zhang said. "Tooth caries happens more than any other kind of chronic and non-contagious diseases, but today's science development has found effective ways to avoid or stop it."

To avoid tooth caries or to stop them from getting worse, people have to brush their teeth with tooth paste that contains fluoride; reduce the frequency of eating sweet food; having regular oral health examinations, and take prompt action against further decaying of the teeth.

"Reducing the frequency of having sweet food is more important than reducing the amount of sweet food people eat," Zhang said. "The average amount of sugar Chinese people take is less than many developed countries. Chinese people need the nutrition from it."

Tooth caries affects milk teeth drastically in China - 77 per cent of Chinese children around 5-6 years old have tooth caries, while in the US, the number is lower than 10 per cent.

Many parents don't pay enough attention to tooth caries in the milk teeth of their children, thinking that the children will get new teeth as they grow.

"That thought is irresponsible, because the bacteria that caused caries in milk teeth doesn't leave with the milk teeth," Zhang said. "Caries in milk teeth largely adds to the possibility of having caries in the newly-grown adult teeth."

In China, mothers used to feed their babies with food they have chewed. Dentists with NCOH also warned that it was a harmful custom, because bacteria will be passed on to the babies' mouth from the mother.

And sugar-free chewing gums can help to prevent tooth caries. NCOH started the research of the caries-proof function of xylitol, a natural sweetener taken from birch trees in Finland in 1996.

Now there are three or four kinds of gums with xylitol in the Chinese market.

A test with xylitol gums produced by Lotte Stone Foods Co Ltd in Beijing showed that chewing a piece of gum within half an hour after a meal largely stops the pH measure of the mouth from dropping - that is, not much acid.

(Shanghai Star August 29, 2002)