Bill, your longtime friend

Your friend Bill, who lives a comfortable jet-setting life, phones in. He says he is in Berlin, Germany, and that he's flying to New York City (you're living in New York), so he said he thought he'd visit you. Here's the transcript of your phone conversation.

(riiing.. riiing..)
You pick up your Nokia Nseries phone.
YOU (u): Hello?
BILL (b): Hey! It's me, Bill!
U: Hey, Bill!
B: Yeah, well I'm in Berlin right now, and I'm leaving for New York tomorrow!
U: [you check your schedule.. ugh, tomorrow's fully packed] Wow.. that's, uhm, great.
B: Yeah! Now, we haven't spoken in years, and it would be really nice to catch up, so might we have coffee tomorrow? The plane's landing at noon.
U: Yeah? What time do you want to do that?
B: Four's fine. We're staying at the Hilton.
U: [checking your schedule again.. four o'clock is your dentist appointment... one of your molars has been killing you] Oh, man.. I've made an appointment with my dentist.. it would really be difficult to reschedule..
B: Oh, come on, man! We haven't spoken in AGES! Just this once, man.. Come on.. I'll introduce you to my third wife, Eva.. she's Spanish..
U: [WHAT WOULD YOU DO?]

Fill in that blank! Would you cancel your appointment to have coffee with a long time friend, or do you ditch him and save your tooth?