Medical Conversation of the Day: Endocarditis and the Dentist

"I'm worried I'm going to get endocarditis [an infection of the heart valves] from going to the dentist."
"You won't. You don't have any risk factors, like heart valve disease."
"But I know someone that got endocarditis from going to the dentist and he didn't have heart valve disease."
"Was he shooting up drugs at the time?"
"Well, yeah, but he was sure he got endocarditis from going to the dentist..."