Each year thousands of people develop sinus infections from various causes. But there's one cause for sinusitis that might surprise you—tooth decay.
Tooth decay begins when the acid produced by oral bacteria erodes a tooth's enamel protection to create a small hole or cavity. Left untreated, the infection can move into the inner pulp of the tooth and tiny passageways leading to the roots called root canals. The decay can then infect and break down the structure of the supporting jawbone.
This could affect the sinus cavities, hollow air-filled spaces in the upper portion of the face. The maxillary sinus in particular sits behind the cheek bones just above the upper jaw. Tooth roots, particularly in back teeth, can extend quite near or even poke through the floor of the maxillary sinus.
If decay affects these roots, the bone beneath this floor may begin to break down and allow the bacterial infection to enter the sinus. We call this particular kind of sinus infection maxillary sinusitis of endodontic origin (MSEO), "endodontic" referring to the interior structure of teeth.
While advanced decay can show symptoms like pain or sensitivity with certain hot or cold foods, it's also possible to have it and not know it directly. But a recurring sinus infection could be an indirect indication that the root of your suffering is a deeply decayed tooth. Treating the sinus infection with antibiotics won't cure this underlying dental problem. For that you'll need to see a dentist or an endodontist, a specialist for interior tooth issues.
The most common way to treat deep tooth decay is with root canal therapy. In this procedure, the dentist enters the decayed tooth's pulp (nerve chamber) and root canals and removes the diseased tissue. They will then fill the empty pulp and root canals with a special filling and seal the tooth to prevent future infection. The procedure stops the infection and saves the tooth—and if you have MSEO, it eliminates the cause of the sinus infection.
So, if you're suffering from chronic sinus infections, you might talk with your dentist about the possibility of a tooth infection. A thorough examination might reveal a decayed tooth in need of treatment.