[gchappel]

99++% chance it passes.
If you did not choke or cough, very unlikely it is in your lung-just like it is very unlikely the carrot you just ate is in your lung.
If it doesn't pass in 3-4days, talk to your doctor (not your dentist) They will probably order an xray to see where it is.
The real question is how many times do you wash it before you put it back in your mouth.
gary

BTW, just crap in a bag and seal it up. Camping stores have bags made for that. You can pan for gold when you get home.
gary