Tokyo (AFP) - A Japanese woman got more than a mouthful when she claimed to have discovered fragments later identified as "dental material" in a McDonald's hamburger, marking the fast-food chain's latest food quality embarrassment.
The discovery of the objects, confirmed by McDonald's to be dental on Friday, comes two days after the company admitted several foreign objects had been found in food at Japanese outlets, including a human tooth in a container of french fries at an outlet in Osaka.
An unidentified woman told the Asahi television network she had found three tiny fragments of what looked like teeth in a burger she bought at a McDonald's outlet in northern Kushiro city in September.
"I took a bite and there was a crunch," the woman said in footage aired Friday, adding that she initially thought it was a piece of sand or stone.
"I can't help thinking that it was (already) in the meat."
A third-party examination determined the opaque white fragments were "dental material", according to company spokeswoman Miwa Yamamoto, saying the substance is commonly used to fill cavities or in other dental work.
McDonald's, however, would not confirm the woman's claim that the fragments were inside her burger.
Yamamoto said the customer was told that there was an "extremely low chance" it could have fallen into raw material, given the highly-mechanised process.
None of the employees at the outlet had issues with their teeth at the time and the customer denied it could have come from her, Yamamoto said.
On Wednesday, McDonald's acknowledged a human tooth had been found in fries sold by another outlet last year, while it has also been hit by incidents in which pieces of vinyl were found in chicken nuggets and a tiny piece of hard plastic in a sundae.
Japanese media reported several other cases of contamination, including a piece of metal in a pancake.
The incidents mark another public relations setback for the firm, which is struggling to recover from a battering to its reputation this summer when a Chinese supplier was found to be mixing out-of-date meat with fresh produce.
Then, late last year, the company had to airlift an emergency supply of french fries from the US after a chip shortage had resulted in rationing at its 3,000 restaurants across Japan.
Labour disputes on the US West Coast had bunged up the export chain, leaving Japanese firms scrambling to secure fresh supplies.
The difficulties looked set to hit McDonald's bottom line, with the Japanese unit earlier saying it was on track to report a 17 billion yen ($142 million) annual loss for 2014.
The subsidiary's Tokyo-listed shares, which are down nearly 10 percent since late July, fell 1.07 percent to 2,503.0 yen on Friday.
The company said the December sales at its existing stores dropped by 21.3 percent from the same month a year ago.
Japan generally has a good record on food safety, and its consumers are used to high standards.
Occasional blunders can prove costly to reputations, and firms that have fallen foul of shoppers have discovered the impact can be long-lasting.