posted by rfvv .
1. She didn't go to a dentist.
2. She didn't go to see a dentist.
3. She didn't go to the dentist.
4. She didn't go to the dentist's.
5. She didn't go to the dentist's office.
(#4 is from #5, right? Does #3 mean "she went to the specific dentist whom she knows" or "she went to the dentist's office"? What are the differences among the sentences?)
All are essentially the same, but 1 and 2 could mean that she went to a dentist the speaker doesn't know, and maybe one she doesn't know either.
Saying "the dentist" implies that both of them know which dentist she went to.