I wish I had taken better care of my teeth as a child, but I didn't.  So, I have 4 fillings that, due to my being 43, are beginning to deteriorate.  The dentist wanted to give me a new one, so that's what I did this morning.  
Now, I've always loved going to the dentist to get my teeth cleaned.  In fact, I wish our health insurance would pay for more than just 2 cleanings per year.  But, fillings...ugh...those are different.
The dentist numbed my mouth and started to drill.  "Tell me if it hurts," he said.  It did and I did.  So he pumped more numbing agent into my mouth, which, for reasons known only to evolution, I suppose, refused to go any more numb.  So, he had to dump the entire contents of the (very scary) needle into my gums.  Well then, 3/4 of my mouth was numb, but I could still feel the drilling.  
Plus, because he had put so much of that stuff in me, my mouth, he warned, would be numb for a longer period of time.  Great.
I was allowed to eat lunch by 12:30pm, but due to my not being able to feel my mouth, I bit my poor lip a few times ("what is that crunchy thing between my teeth?").  I should tell the kids it serves as a warning to them, but they're so dim sometimes that it'll be in one ear and out the other.
"To be conscious that you are ignorant is a great step to knowledge." ~ Benjamin Disraeli (1804 - 1881)
 
