The health authority said elderly people performed better than middle-aged people when it comes to oral health. Elderly people ranging in age from 65 to 74 in China had 22.5 teeth on average, 1.5 more teeth than 10 years ago, which is a major improvement.

However, the rate of gingival bleeding and dental tartar (hardened plaque) among people aged 35 to 44, were 87.4 percent and 96.7 percent respectively, suggesting there's still plenty of room for improvement.

Wang Xing, an adviser for the Chinese Stomatological Association, said the main reasons middle-aged people have worse oral health lies in their heavy work stress and insufficient attention.

"Many middle-aged people are buried in work, and are short of time and energy to pay attention to their oral health. In addition, a number of them don't regard oral diseases as real diseases," Wang said. "They don't attach enough importance to it until they are unable to bear a toothache."

The investigation also shows a gap between cities and villages. People in cities performed better than those in rural areas in every aspect. In many rural areas, poor people do not go to the hospital for dental care because the high expenses are not covered by medical insurance.

Chang Jile, an official of the National Health and Family Planning Commission, said the government is working to extend the range of medical healthcare and to establish special programs.

"We have set up several programs aimed at certain oral diseases that will ease people's financial burden," Chang said. "For example, we have helped 12,000 elderly people in poor areas get their teeth filled for free and will continue to do so."

Jiang Chenglong contributed to this story.