Beijing, Aug 22 (PTI) In ancient China, it was considered impolite for well-bred ladies to show their teeth while smiling.
Today, some young people purse their lips while smiling – not because they are following any tradition but because they do not want to expose their discoloured molars.
Statistics from the Ministry of Health show that 40 million people’s smiles are affected by fluorosis – one of the most serious regional diseases in China.
That is to say, one in every 30 Chinese people has the disease, ‘China Daily’ reported.
The ingestion of excess fluoride, most common in drinking water, can cause fluorosis, which affects the teeth and bones, World Health Organisation said.
By the end of 2003, 38.7 million Chinese people were suffering from dental fluorosis, and 2.84 million people were affected by skeletal fluorosis.
Dental fluorosis is characterised by the staining and pitting of the teeth, with some severe cases in which all the enamel may be damaged.
In skeletal fluorosis, fluoride accumulates in the bone progressively over many years, with symptoms such as stiffness and pain in the joins.
The bone structure may change and ligaments may calcify, resulting in the impairment of muscles, and pain.
In China, the disease is found to be most severe in Southwest China’s Guizhou Province, where coal is the major fuel for cooking.