I feel numb for almost 3 days now, and my dentist ask me to wait for another day to see whether the numb would go away...will it?

What started it?: Did you see a dentist who gave you an injection of anesthetic? In which case it typically wears off in a few hours. Are you numb on the lower jaw after extraction of impacted wisdom teeth? Then the numbness may be temporary or permanent. Are you numb from a traumatic injury? Then you need to see a dentist or oral surgeon (specialist) immediately. See a different dentist for an evaluation.

Depends: You haven't explained why or where you are numb. Is it in response to a procedure , an infection, trauma, etc. The answer to your question will vary with the cause. Please re-ask question with more details.

Depends: Why do you have numbness? Did you get an injection, a tooth extracted, or are you infected? Each of these can cause numbness. You and your dentist know what transpired. Explain further and maybe we can help.