Sinusitis is an inflammation of the cavities(sinus spaces)  present around the nose. In cases of acute sinusitis , most often caused by cold, there is a build up of mucus in these cavities.  This may often lead to pain  in the upper back  teeth area. The roots of upper molars  often extend into the sinus area.

In case of pain in upper molar teeth , dental causes like cavities or gum problems can also lead to persistent/intermediate pain .These  causes should also be treated /eliminated as cause of pain in upper molar teeth.