Would the dentist know if I brushed my teeth before I visited them?

Yes, the dentist can see whether there is the normal film on your teeth. That film is removed by brushing. If it is gone, you have brushed. It's as simple as that.

Of course, if you are not brushing regularly, you will have a lot of tartar build up, and the dentist will see that as well. (You might have excess tartar even if you do brush, but it will certainly be there if you aren't brushing every day, or if you aren't brushing long enough.)

But the basic answer to your question is yes, it is usually pretty clear whether the patient has brushed before the visit.

Yes, I do brush my teeth before visiting the dentist.

When i was g kid i asked the same question..but never got an answer :(

mine told me she does and thats why shes got this strong mouth wash

i have done this and no... but they dont take as long