Can Teeth Cause Sinus Problems?

Teeth are one of the most common causes of sinus infections, and the connection is far more direct than most people realize. The roots of your upper back teeth sit remarkably close to the floor of the maxillary sinus, sometimes separated by less than a millimeter of bone or even poking through into the sinus cavity itself. When infection, gum disease, or a dental procedure breaches that thin barrier, bacteria can spread into the sinus and trigger a condition called odontogenic sinusitis. Studies suggest dental problems account for roughly 30 to 40 percent of maxillary sinus infections, yet the dental origin goes unrecognized in the majority of cases.

Why Your Upper Teeth Sit So Close to Your Sinuses

The maxillary sinus is a hollow, air-filled space behind your cheekbone, and its floor hangs directly over the roots of your upper premolars and molars. In many people, the bone separating root tips from the sinus is paper-thin. Imaging studies show that the roots closest to the sinus floor are typically those of the second molars, while the first molars and second premolars are not far behind.¹ In some individuals, roots actually protrude into the sinus cavity. One study found that the buccal roots of the upper molars were the most likely to push through the sinus floor, and that the bone on the cheek side of first premolars and first molars was significantly thinner than in other locations.²

This closeness is not the same for everyone. People with narrower upper jaws tend to have even shorter distances between their premolar roots and the sinus wall compared to people with normal jaw width.³ Age matters too: the sinus gradually expands over a person’s lifetime, sometimes dipping lower between the roots of teeth. The practical upshot is that for a large slice of the population, the barrier between an infected tooth and the sinus is barely there.

How Dental Infections Spread to the Sinus

When a tooth develops a deep cavity, a dying nerve, or advanced gum disease, bacteria multiply around the root tip and form an abscess or area of chronic infection. If that infection is close enough to the sinus floor, bacteria can cross into the sinus and provoke inflammation of the Schneiderian membrane, the thin lining that covers the inside of the sinus. That lining swells and thickens, fluid accumulates, and the natural drainage opening of the sinus can become blocked, trapping the infection inside.⁴

Gum disease alone can do this even without an abscess. Periodontitis gradually destroys the bone surrounding the tooth roots. As bone loss deepens, the remaining bone between the root and the sinus shrinks, and the inflamed tissues push closer to the sinus lining. Research using 3D imaging has found that people with moderate to severe bone loss from gum disease had roughly 1.8 times the risk of sinus-lining thickening compared to those with only mild bone loss.⁵ Another study confirmed that the severity of sinus-lining thickening tracked directly with the amount of bone loss and the height of remaining bone above the root.⁶

An encouraging finding: the sinus lining can recover. In patients who had severely periodontally compromised teeth extracted and the area cleaned up, sinus-lining thickening dropped noticeably within about four months.⁷ In other words, remove the dental source and the sinus often calms down on its own.

How Common Is Tooth-Related Sinusitis?

The connection is far from rare. When researchers looked specifically at CT scans showing one-sided sinus disease, dental infection turned out to be the leading cause, identified in about 70 percent of unilateral maxillary sinusitis cases.⁸ Another study examined how the degree of sinus blockage on a CT scan correlated with a dental source. In sinuses that were more than two-thirds filled with fluid, about 79 percent had an identifiable dental cause. When both heavy fluid buildup and significant lining thickening were present, that number rose to 86 percent.⁹

These numbers may surprise you, because odontogenic sinusitis has historically been considered uncommon by ear-nose-throat specialists. Recent imaging advances have changed that picture dramatically. Broader estimates from the literature now place dental causes behind 30 to 40 percent of all maxillary sinus infections, making it one of the single largest contributors to chronic or recurrent sinus trouble on one side of the face.¹⁰

Dental Procedures That Can Trigger Sinus Problems

It is not only untreated dental disease that puts the sinuses at risk. Several routine dental procedures can create or worsen sinus issues when things do not go perfectly.

Tooth extraction is the most straightforward path. Pulling an upper molar or premolar can occasionally tear through the thin bone floor and create an opening between the mouth and the sinus, known as an oroantral communication. If that hole does not heal properly, it can become a permanent passage called an oroantral fistula. The reported rate of this complication ranges from less than 1 percent to about 5 percent of upper back-tooth extractions.¹¹ Even without an obvious perforation, extracting a tooth whose roots were embedded in or near the sinus can introduce oral bacteria into the sinus space.¹²

Dental implants can cause problems when placed in the upper jaw, particularly when a sinus-lift procedure is performed to add bone height. If an implant protrudes into the sinus or blocks the sinus drainage opening, it can set off an infection.¹³

Root canal treatment occasionally plays a role as well. If filling material is pushed past the root tip and into the sinus, the foreign material can spark chronic inflammation. In healthy patients, overfilled root canal material containing zinc oxide and eugenol has even been linked to fungal sinus infections, because the material appears to provide a growth surface for Aspergillus fungi.¹⁴ These cases are uncommon, but they underscore that any procedure near the sinus floor carries some risk.

Symptoms and Why They Get Misdiagnosed

Odontogenic sinusitis feels a lot like regular sinusitis: stuffiness on one side, facial pressure or pain around the cheek, postnasal drip, and sometimes a headache. One symptom that leans heavily toward a dental origin is a foul smell, either from the nose or noticed by others. Dental pain itself is infrequent, which makes the dental connection easy to miss. Many patients have no toothache at all and only complain of sinus symptoms.

The confusion runs in both directions. A sinus infection that started without any dental cause can refer pain downward into the upper teeth, mimicking a toothache. The nerve pathways serving the upper back teeth run through the same region as those serving the sinus lining, so an inflamed sinus can make healthy teeth ache.¹⁵ This bidirectional mimicry means patients sometimes bounce between a dentist and an ENT without either specialist considering the other’s domain.

The microbiology adds another layer. Tooth-related sinus infections tend to harbor a different mix of bacteria than typical rhinogenic (nose-originating) sinusitis. They are often polymicrobial, with a heavy presence of anaerobes, the kinds of bacteria that thrive in oxygen-poor environments like the deep pockets of gum disease or a dead tooth.¹⁶ Standard antibiotic choices for typical sinusitis may not cover these organisms well, which is one reason tooth-related sinus infections often fail to respond to the first round of antibiotics and keep coming back.

The Problem of Overlooked Dental Findings on Sinus Scans

Even when a patient gets a CT scan of the sinuses, the dental source is missed more often than you might expect. One study found that among patients with one-sided sinus disease, about two-thirds of CT reports made no mention of dental pathology at all.¹⁷ Another study estimated the cause of sinusitis was likely dental in 30 percent of cases, yet only about 8.5 percent of radiology reports raised the suspicion of an odontogenic origin.¹⁸

Why the gap? Radiologists reading sinus CTs are trained to focus on the sinuses, not the teeth. The roots of upper teeth are often visible at the bottom of the scan, but dental pathology is easy to overlook if you are not specifically looking for it. When one research team had an oral and maxillofacial radiologist re-read sinus CTs that had originally been reported as showing no dental problems, the specialist identified apical infections, severe bone loss, underfilled root canals, and other dental findings in dozens of exams.¹⁹ The practical takeaway for patients: if you have recurring or one-sided sinus infections, ask specifically whether a dental cause has been considered. Do not assume the CT report covered it.

Standard two-dimensional dental X-rays are also limited. Panoramic images and single-tooth films have lower sensitivity for picking up both sinus disease and certain types of periapical infections.²⁰ Three-dimensional cone-beam CT, which is increasingly available in dental offices, offers a much clearer picture of the relationship between the tooth roots, surrounding bone, and sinus cavity. It has become the imaging tool of choice when odontogenic sinusitis is suspected.²¹

How Tooth-Related Sinus Infections Are Treated

The single most important step is dealing with the offending tooth. If a dead or abscessed tooth is the source, root canal treatment or extraction removes the reservoir of bacteria. If gum disease is responsible, deep cleaning or extraction of a hopeless tooth eliminates the pathway. In many cases, this dental treatment combined with a course of antibiotics is enough to resolve the sinus infection. In one study, about two-thirds of patients with odontogenic sinusitis were cured with dental treatment and medication alone, without needing sinus surgery.²²

When dental treatment alone does not clear the sinus disease, the next step is endoscopic sinus surgery, a minimally invasive procedure where an ENT surgeon opens the blocked sinus drainage pathway. A cohort study comparing dental treatment alone to dental treatment plus sinus surgery found that the combined approach had a higher success rate, around 96 percent versus about 85 percent, and patients in the combined group had better outcomes on sinus scoring measures at three and six months.²³ The patients most likely to need surgery in addition to dental work tend to be smokers and those whose CT scans show more extensive sinus disease at the outset.²²

Crucially, sinus surgery without addressing the dental cause is a recipe for failure. If the infected tooth or fistula remains, the sinus keeps getting reinfected from below. This is one of the main reasons some patients endure multiple sinus surgeries without relief: nobody looked at the teeth.²⁴

How It Affects Daily Life

Chronic sinusitis of any kind takes a toll on sleep, concentration, and general well-being, but research suggests the dental variety may hit harder than its rhinogenic counterpart. A study comparing patients with odontogenic chronic rhinosinusitis to those with non-dental chronic rhinosinusitis found that while both groups reported similar sinus symptom scores, the odontogenic group scored significantly worse on a general health-related quality-of-life measure. The same level of sinus symptoms appeared to have a greater impact on overall well-being when the cause was dental.²⁵ That may partly reflect the frustration of a condition that keeps relapsing because its root cause has been missed.

When Untreated Dental Sinusitis Gets Dangerous

Left alone, tooth-related sinus infections can do more than cause chronic congestion. The maxillary sinus communicates with the other paranasal sinuses and sits beneath the orbit of the eye and near the floor of the brain case. In rare but serious scenarios, infection can spread beyond the sinus to involve the eye socket or even the brain. A case report documented a brain abscess that originated from a tooth with untreated root inflammation; the infection had first eroded through the maxillary sinus wall and eventually tracked upward.²⁶ Complications like this are exceptional, not the norm, but they illustrate why persistent one-sided sinus symptoms deserve a thorough workup that includes the teeth.

Odontogenic Sinusitis in Children

Adults are far more commonly affected, for the simple reason that kids’ maxillary sinuses are still developing and their permanent molar roots have not yet fully formed. The sinus expands as a child grows, and the roots of the permanent teeth descend closer to the sinus floor over time. By the teenage years, the anatomical relationship starts to resemble that of an adult.

That said, odontogenic sinusitis does occur in children, particularly in adolescents who have cavities in their first permanent molars or who have experienced dental trauma. A systematic review noted that the clinical picture in children mirrors the adult version, with nasal obstruction, discharge, and facial pain as common symptoms, while dental pain is often absent. A foul smell from the nose is a useful red flag at any age.¹⁰ Because pediatricians may not think to examine the teeth when evaluating sinus symptoms, the dental source can be overlooked for even longer in younger patients than in adults.

Signs You Should Suspect a Dental Cause

Not every sinus infection comes from a tooth, of course, and sorting out the cause usually requires imaging. But certain patterns make a dental origin more likely:

One-sided symptoms: Typical viral or allergic sinusitis tends to affect both sides. When congestion, pain, or discharge is clearly worse on just one side, a dental source should be considered.
Foul smell: A persistent bad odor from the nose or a metallic, rotten taste, especially on one side, is strongly suggestive of anaerobic bacterial infection tracking from a tooth.
Recent dental work: Sinus symptoms that begin within days or weeks of an upper molar extraction, implant placement, or root canal should raise suspicion for a procedural complication.
Recurrent or treatment-resistant infections: If antibiotics clear the sinus infection temporarily but it keeps returning, the ongoing source is probably something antibiotics cannot eliminate, like a dead tooth or a chronic fistula.
Known dental problems: A history of deep cavities, failed root canals, or advanced gum disease in the upper back teeth makes odontogenic sinusitis considerably more likely.

If any of those patterns sound familiar, the most productive next step is to bring the question directly to both your dentist and your ENT, and to ask whether a cone-beam CT has been considered. A standard sinus CT read by a general radiologist can easily miss the dental connection, as the studies above show. The more specific imaging gets, the harder it becomes for the dental culprit to hide.