A teacher illustrates the structure of teeth and gum to children while teaching them how to brush their teeth correctly at a kindergarten in Changxing County of Huzhou, east China's Zhejiang Province, Sept. 16, 2020. China's health authority has required sound efforts in promoting the awareness of dental health among the public as part of the campaign for the country's dental care day, which falls on Sept. 20. (Xinhua/Xu Yu)

A teacher illustrates the structure of teeth and gum to children while teaching them how to brush their teeth correctly at a kindergarten in Changxing County of Huzhou, east China's Zhejiang Province, Sept. 16, 2020. China's health authority has required sound efforts in promoting the awareness of dental health among the public as part of the campaign for the country's dental care day, which falls on Sept. 20. (Xinhua/Xu Yu)

Children learn how to brush their teeth correctly at a kindergarten in Changxing County of Huzhou, east China's Zhejiang Province, Sept. 16, 2020. China's health authority has required sound efforts in promoting the awareness of dental health among the public as part of the campaign for the country's dental care day, which falls on Sept. 20. (Xinhua/Xu Yu)

A teacher teaches a child to brush teeth correctly at a kindergarten in Changxing County of Huzhou, east China's Zhejiang Province, Sept. 16, 2020. China's health authority has required sound efforts in promoting the awareness of dental health among the public as part of the campaign for the country's dental care day, which falls on Sept. 20. (Xinhua/Xu Yu)

Children learn how to brush their teeth correctly at a kindergarten in Changxing County of Huzhou, east China's Zhejiang Province, Sept. 16, 2020. China's health authority has required sound efforts in promoting the awareness of dental health among the public as part of the campaign for the country's dental care day, which falls on Sept. 20. (Xinhua/Xu Yu)

Children learn how to brush their teeth correctly at a kindergarten in Changxing County of Huzhou, east China's Zhejiang Province, Sept. 16, 2020. China's health authority has required sound efforts in promoting the awareness of dental health among the public as part of the campaign for the country's dental care day, which falls on Sept. 20. (Xinhua/Xu Yu)