Authorities have banned online sales of unapproved "fad" teeth braces promoted by actors and net idols, warning they may be substandard and could even prove fatal.

Dr Paisal Kangwolkij, president of the Dental Council, told the press on Wednesday that authorities imposed the ban because some of the multicoloured braces have leaked heavy metals, including cadmium, and caused mouth damage. 

One youngster died of heart disease that had been linked to the braces, he claimed, adding that heavy metals constantly seeping out of the braces could also cause liver damage and cancer. 

"The Consumer Protection Board has issued and imposed a ban on sales of unapproved teeth braces. So all online teeth brace services and online sales of all brace materials including retainers are illegal," Dr Paisal said.

"Legal teeth brace services are unavailable online. Legal teeth braces must be provided by dentists who must examine users before fitting the braces."

Violators of the ban are subject to up to five years in jail and/or a fine of up to 500,000 baht.

Dr Tongchai Wachirarotepaisal from the Consumer Protection Board said that since last April there had been complaints against 308 shops selling fad teeth braces in 19 provinces, and local health officials and police were taking legal action against them.

Dr Paisal said that actors and net idols had promoted their products and services.

The Food and Drug Administration (FDA) has issued a regulation to control the import, production and sale of teeth brace materials.

FDA deputy secretary-general Somchai Preechathaweekit said authorities had raided a large, registered teeth brace factory in Ratchaburi province that supplied products to online operators, and the plant owner would face legal action.