I've been really lucky with my dentists. I've only ever had two really traumatic experiences, both since I came to university (wisdom tooth extractions!).
However I'm terrified of dentists, I've got no idea why. The best dentist I had was when I was 11 up to 16 when he retired. When I was 14 I had three new teeth come through and my mother told me (jokingly) they were probably wisdom teeth. My in my innocence told the dentist who said
"Don't be silly, you're much too...Bloody hell!"
The bloody Hell was him taking a look in my mouth and finding three extra teeth. He then spent 5 minutes counting because he couldn't believe it.
They were wisdom teeth after all!
Unfortunatly the two top ones grew in a strange way with a huge crack down the middle making them almost impossible to clean and they rotted painfully from the inside, nessesitating their removal. That was a terrible experience, incredably painful and stressful. I hope I never have to go through that again!