When a tooth is extracted a clot forms in the empty space. This is a natural process that protects the area during the time it takes to heal. If for some reason the clot does not form, or if it tears, your jawbone will be exposed to bacteria. This condition is known as dry socket.
The pain that goes along with dry socket can be severe and incessant sometimes even radiating to your ears. There will also be swelling.
Your dentist will examine the point of extraction to see if the bone has been exposed. He will test for sensitivity and take xrays to look for bone fragments.
After numbing the infected area your dentist will flush it out and pack the socket with a compress that has been treated with an antibiotic, an antifungal agent and a pain medication. The compress will be left to be absorbed into the gum. Your dentist will prescribe additional pain relievers as needed. Give yourself a week or so to heal.