Every morning that this 38-year-old man from Northern England wakes up, he believes he's going to his dentist later that day for his root canal surgery. But that appointment was back in March 2005 and he already went to it. Since that dentist visit, the man, known only by the name William, can no longer remember anything longer than 90 minutes.

He has been living with this condition for 10 years.

His case is being studied by baffled doctors who are searching for the answers that could help William, according to ABC News.

"I remember getting into the chair and the dentist inserting the local anesthetic," the patient said.

The dentist gave him routine anesthesia, but his psychologist said that the memory loss could not have been just due to a common procedure. 

"One thing is that we should perhaps not be so stuck in thinking that profound amnesia only occurs in the context of visible damage to the brain's structures," said William's psychologist, Gerald Burgess. He believes a "neuro-chemical or neuro-electrical event" may have happened during the 50-minute root canal and hopes other neurologists would be able to help his patient.

William's other doctors suspect he has anterograde amnesia due to a brain hemorrhage that may have damaged his hippocampi, which affects memory storage. But there seem to be no evidence of this. Doctors also ruled out repressed memories due to trauma.

"He was a successful father and military officer with good job evaluations. There was no reason to think that there was anything wrong psychiatrically," Buress said, according to the New York Daily News.

William, a Gulf war veteran, had been taken to the hospital and was confined for three days following the dentist appointment, but doctors couldn't tell what was wrong with him.

Today, he goes through his daily activities with the help of his wife, Samantha, who logs a list of events on his computer. Yet sometimes, William "continue(s) to elicit genuine surprise or astonishment each time he sees or hears about them, such as the marriage of some family friends or that a family pet has since passed away," the researchers said in their study.

The doctors have published the full report on William's case in the journal Neurocase.