The roots of the upper back teeth sit very close to the sinus floor. Sinusitis can therefore feel like toothache, and a dental infection like sinusitis; here is how to tell.
Some patients who arrive saying "all my upper teeth hurt" have a problem not in the teeth but in the space directly above them. The reverse is also true: a patient treated for sinusitis for months may in fact have a problem at the root of a single tooth.
Why the two are so easily confused
In the upper jaw, within the bone below the eye, lies an air space called the maxillary sinus. The roots of the upper premolars and molars sit very close to its floor; in some people only a paper-thin layer of bone separates them, and sometimes a root projects into the sinus itself.
Sensation from both regions is also carried by the same nerve branches. The brain cannot always assign signals from neighbouring structures to the right address; this is called referred pain.
What sinus pain typically feels like
In sinus pain several upper back teeth on the same side usually ache together rather than one tooth. The pain is dull, pressing and diffuse; the patient often cannot point to a single tooth.
- Worsens on bending forward, sneezing or going down stairs
- Accompanied by nasal blockage, discharge or post-nasal drip
- There is a sense of fullness in the cheek and below the eye
- Usually begins after an upper respiratory infection
- The sense of smell may be reduced
What dental pain typically feels like
Dental pain usually centres on a single tooth and the patient can point to it. It responds distinctly to hot and cold; pain that increases with heat and eases briefly with cold is the classic description of pulpitis.
Sharp pain on biting or tapping the tooth shows the problem has reached the root tip. In sinusitis, tapping a single tooth does not produce this response; it is one of the most discriminating tests in the examination.
A simple distinction you can make at home
It does not give a diagnosis but it points a direction: bend your head forward and wait thirty seconds. If the pain increases clearly and eases on straightening, sinus origin is likely. Dental pain is usually unaffected by this manoeuvre.
The second clue is a cold water test. If a mouthful of cold water produces a sharp pain lasting seconds in one specific tooth, the problem is most likely in that tooth.
What is checked at the examination
The dentist tests each tooth in turn: percussion, a cold test and, where needed, an electric vitality test. The aim is either to narrow the source to a single tooth or to show that all the teeth are healthy.
Imaging is decisive here. A periapical radiograph shows inflammation at the root tip, while a CT scan reveals both the relationship of the root to the sinus and any thickening of the sinus floor at once. In doubtful cases a scan ends the uncertainty.
Sinusitis arising from a tooth
A significant share of sinusitis is of dental origin. An infection at a root tip can cross the thin bone and inflame the sinus lining. The distinguishing features are that it is one-sided and that the discharge has a foul smell.
Antibiotics and a nasal spray give temporary relief here but the problem returns, because the source remains in the tooth. The lasting solution is root canal treatment of that tooth, or extraction where necessary.
Sinus opening after an extraction
During extraction of an upper molar whose roots lie very close to the sinus, the thin plate of bone can break and create a communication between mouth and sinus. Patients notice it when liquid comes through the nose while drinking, or when air escapes from the socket on sniffing.
Small openings close on their own; larger ones are closed with sutures. During this period avoid blowing the nose hard, sniffing forcefully and drinking through a straw; the pressure disrupts healing.
Which to see first
Where there is nasal blockage, discharge and a recent upper respiratory infection, an ENT assessment may take priority. Where pain centres on one tooth, worsens on biting and is provoked by heat, the dentist should be seen first.
When in doubt, starting with a dental examination is practical, because a dental source can largely be excluded with a few minutes of testing. Where complaints recur despite treatment for sinusitis, the teeth must be reassessed.
