Can a Root Canal Cause a Sinus Infection? What Is Going On

Why the Tooth and the Sinus Are Connected

The maxillary sinuses are air pockets in the cheekbones, directly above the upper molars and premolars. The roots of those teeth can sit very close to the sinus floor, separated by a thin layer of bone. Lower teeth have no such neighbour, so a root canal on a lower tooth is not a sinus matter at all.

Because of that closeness, infection can travel in either direction. Our post on telling a sinus infection from a toothache covers the difference in detail.

The Three Usual Explanations

When someone develops sinus symptoms after a root canal on an upper tooth, it is almost always one of these:

• The tooth was already infecting the sinus. An infection at the root tip can spread upward into the sinus (dentists call this odontogenic sinusitis). The sinus symptoms were there before the root canal, or started just as the tooth did.
• The infection has not fully cleared. A canal that was missed, or one that was not sealed well, can leave bacteria behind. See our post on whether a root canal can get infected.
• An ordinary sinus infection arrived by coincidence. Colds are common and sinuses do not check the dental diary.

Much more rarely, filling material pushed slightly past the root tip reaches the sinus and irritates it. That is the one case where the procedure itself is involved, and it shows up on an X-ray.

Signs That Point to the Tooth

A sinus infection that comes from a tooth tends to look different from a cold that settled in the face:

• It is on one side only, and the ache sits in the cheek or in the upper teeth on that side
• One tooth is tender to bite on or to tap
• A bad taste, or a bad smell from one nostril
• It does not clear with the usual decongestants and rest

Pain in both cheeks, a streaming nose and a sore throat point more towards the sinus alone. Our post on a tooth that still hurts after a root canal explains what normal healing feels like, so you can compare.

Getting It Looked At in Beit Shemesh

The awkward version of this is a swollen cheek on Thursday night. We are open Sunday to Thursday, 8:00 AM to 8:00 PM, and Friday 9:00 AM to 5:00 PM. Shabbat is for genuine emergencies only, so a one-sided facial ache that appears late in the week should not be left to carry itself through the weekend.

Same-day appointments are possible at our Beit Shemesh clinic when we have room. Dr. Joel trained in the United States and treats in Hebrew and English, which helps when the honest description is "it is sort of my tooth and sort of my face". An X-ray of the treated tooth shows whether the root tip is clear, and that answer usually settles the question.

What Fixes It

It depends on which explanation is true. If the tooth is the source, the fix is at the tooth: retreating the root canal to clean out what was missed, or an extraction if the tooth cannot be saved. The sinus usually settles on its own once the source is gone. If the tooth is clear, the sinus is a job for your family doctor or an ENT, and we will tell you so rather than treat a tooth that is not the problem.

See our root canal treatment page in Beit Shemesh for what we do. The American Association of Endodontists and ADA MouthHealthy both describe the link between upper teeth and the sinuses.

When You Do Not Need Us, and When You Need a Hospital

If your teeth feel fine, nothing hurts to bite on, and the pressure is in both cheeks with a cold, start with your doctor or pharmacist. A root canal that was done months ago and feels normal is rarely the cause.

Go to a hospital emergency department, not a dental appointment, if you have swelling around or behind the eye, double vision, a high fever with a severe headache, a stiff neck, or confusion. Those are signs of infection spreading beyond the sinus and need a doctor tonight.

If you have a treated upper tooth and a sinus that will not settle, call or WhatsApp 055-985-8845. We are at Harav Kook 28/1 in Beit Shemesh, Sunday to Thursday 8:00 AM to 8:00 PM and Friday 9:00 AM to 5:00 PM, with same-day appointments where we have them.