Here’s a new reason to be scared of the dentist.

A 48-year-old man hasn’t been able to remember anything new since having a routine root canal 10 years ago.

“I remember getting to the chair and the dentist inserting the local anesthetic,” the patient, named William, told the BBC. Since then, he’s been unable to remember anything for longer than 90 minutes.

In May, William’s medical team published a report on his condition in the journal Neurocase. “We had never seen anything like it before,” wrote Dr. Gerald Burgess, a clinical psychological at the University of Leicester. “We do not know what to make of it.”

The British veteran, who was stationed as a soldier in Germany at the time, is believed to be suffering from a type of memory loss known as anterograde amnesia. But without any damage to his brain, or signs of psychological trauma, neuropsychologists have no clue what could have caused it. “It is a bit of a head-scratcher,” John Aggleton, a professor of cognitive neuroscience at Cardiff University, told the BBC.

Burgess — who doesn’t believe the memory loss can be attributed to the dental procedure — hopes the report’s publication will attract other neurologists who may have dealt with similar cases.

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