What is it?
The maxillary sinus is an air space that sits under your cheekbone. The roots of the upper molars and premolars lie very close to the floor of this space; in some people only a paper-thin layer of bone separates them, and in others there is no bone at all. When an infection at the root tip, or bone loss from gum disease, crosses that border, the lining of the sinus becomes inflamed.
Sinusitis that comes from a tooth differs from ordinary sinusitis in a few ways. It is usually one-sided, and it starts quietly rather than after a cold. The discharge and your breath may smell unpleasant, and a stubborn bad taste in the mouth is common. Bending forward increases the pressure in your face; the upper back teeth feel full and tender as a group rather than one by one.
The tooth behind it does not always hurt. An infection at a root tip that has been silent for a long time, an unfinished root canal treatment or a procedure carried out years ago may be keeping the picture going. That is why the upper teeth are also expected to be assessed when one-sided sinusitis keeps returning.
Signs
You will not necessarily have all of these at once.
Why does it happen?
- 01
Upper teeth with an infection at the root tip
Infection collecting at the tip of a dead tooth, or of one whose root canal treatment was left unfinished, can dissolve bone and reach the floor of the sinus. These teeth are painless most of the time, and you may come in with nasal symptoms alone.
- 02
Advanced gum disease
When bone loss around the upper molars deepens, the bacteria in the pocket come close to the floor of the sinus. A loose tooth and discharge from the gum can point to this route.
- 03
After dental treatment and surgery
Root filling material pushed into the sinus, a root fragment pushed up during an extraction, implants and sinus floor elevation can all affect the sinus lining directly. Symptoms may also begin weeks after the procedure.
- 04
Root tips lying close to the sinus
In some people the root tips bulge up into the sinus space. With this anatomy even a small infection passes into the sinus easily; the relationship can be seen in advance on imaging taken before treatment.
How does it progress?
- 1
The quiet phase of the source
There is infection in the tooth but no symptoms. It is most often noticed on an X-ray taken for another reason.
- 2
Thickening of the sinus lining
One-sided fullness, postnasal drip and a vague pressure in the upper back teeth begin. Pain is not yet obvious.
- 3
Infection filling the sinus
A blocked nose, foul-smelling discharge and a bad taste in the mouth come to the fore. Bending forward and jumping make it worse.
- 4
A recurring pattern
Medication settles the symptoms, but because the source tooth is still there they come back after a while. One-sided sinusitis that returns a few times a year suggests this picture.
How is it treated?
The diagnosis is made with imaging alongside the clinical examination. A panoramic X-ray does not show the relationship between the roots and the sinus well enough; a cone beam CT scan shows both the source and how full the sinus is. An endoscopic examination by an ENT specialist completes that information.
The dentist's job is to deal with the source. Depending on the state of the tooth, root canal treatment, root-end surgery or extraction is planned; if the tooth is to be taken out, whether an opening has been left between the mouth and the sinus is checked at the same appointment. Treating the sinus cavity itself is not the dentist's field.
Treatment aimed at the sinus belongs to an ENT specialist; nasal medicines, rinses and, in patients where it is thought necessary, an endoscopic procedure are considered under that heading. The two treatments are most often planned together. When only the sinus is treated, the source stays where it is, so the symptoms are expected to come back.
- Swelling and redness of the eyelid and around the eye
- Blurred vision, double vision or restricted eye movement
- One-sided facial pain and swelling rising quickly with a high temperature
- Severe headache, a stiff neck or confusion
How is it prevented?
- Do not let infections at the root tips of your upper back teeth drag on; being silent does not mean they need no treatment.
- Have unfinished root canal treatments completed, and have your follow-up X-rays taken at the interval your dentist advises.
- In gum disease, bone loss around the upper molars is monitored; do not skip your regular gum care appointments.
- Tell your dentist as well if your sinusitis is one-sided and keeps coming back; that is the information that links the two fields.
Frequently asked questions
- My teeth do not hurt. Can my sinusitis still be coming from a tooth?
- It can. The source tooth is painless most of the time, and infection at the root tip can stay silent for a long time. Symptoms that stay on one side, discharge that smells and a picture that keeps coming back despite treatment are findings that call for the upper teeth to be examined too.
- Is a panoramic X-ray enough to show this?
- Most of the time it is not. On a panoramic X-ray the root tips and the floor of the sinus overlap, so the relationship between them is not clear. A cone beam CT scan is preferred here because it shows the source and how full the sinus is separately.
- If the source tooth is treated, will the sinusitis go?
- Once the source is gone, the symptoms are expected to settle; however, infection that has settled inside the sinus may need treating in its own right. For that reason an ENT check after the dental treatment most often stays part of the plan.
This content is for general information and does not replace an in-person examination. Symptoms overlap between conditions, and a diagnosis can only be made clinically.