When surgery involves treating an upper tooth, the root tips are often very close to the sinus in your upper jaw.  If a hole in the sinus is detected during surgery then additional precautions are needed.  In this situation, take the prescribed antibiotic and decongestant as directed.  In addition, it is very important that you avoid pressure changes in the nose for several weeks.  This means you should not blow your nose and when you sneeze, you should cover your mouth and let the sneeze come entirely out of the mouth.  By following these precautions, the hole in the sinus will heal after a few weeks.  After a few months, new bone will grow in the area.