If water or another drink runs out of your nose after an upper back tooth has been taken out, the socket may have opened into the maxillary sinus, the air space above the upper teeth. This is called an oroantral communication. Small openings often close as the socket heals, so it is not usually a reason to panic, but it is a reason to call the practice that day rather than wait for your review appointment.
The roots of upper back teeth can sit millimetres from the sinus
The maxillary sinus sits directly above the upper premolars and molars. In a CT study of 12 autopsy specimens and 38 people, Eberhardt and colleagues (Oral Surgery, Oral Medicine, Oral Pathology, 1992) found the root tip closest to the sinus floor was the mesiobuccal root (the front, cheek-side root) of the upper second molar, at a mean distance of 1.97 mm. The buccal (cheek-side) root of the first premolar sat furthest away, at a mean of 7.05 mm. A 2025 review by Alomari and colleagues notes that in some people the sinus floor is very close to, or even in direct contact with, the root tips.
An oroantral communication happens when the thin wall of bone between the tooth socket and the sinus is breached during an extraction. With a small opening and no sinus infection, the blood clot that forms in the socket may allow it to heal on its own. Larger openings are less likely to close this way, and air and fluid can then pass between mouth and nose.
How often it happens depends mostly on the tooth and the extraction
Most of the research comes from upper wisdom teeth, where the sinus is often very close. In a prospective study across four German university clinics, Rothamel and colleagues (British Journal of Oral and Maxillofacial Surgery, 2007) followed 1,057 upper wisdom tooth removals. An opening into the sinus was found in 13% overall: 24% of completely impacted teeth, 10% of partially impacted teeth and 5% of fully erupted teeth. In 83% of those cases the opening measured less than 3 mm. A root breaking during the extraction, deeper impaction and older age were linked with a higher chance of an opening.
In a retrospective study of 1,562 upper wisdom tooth removals at the University of Zurich, Pourmand and colleagues (Swiss Dental Journal, 2014) recorded an oroantral fistula (an opening into the sinus) in 2.4% of cases. The risk rose with age and with root fractures, and the way the root tips projected onto the sinus floor on the pre-operative panoramic X-ray helped predict it.
Openings are not limited to wisdom teeth. Alomari and colleagues (Saudi Dental Journal, 2025), citing earlier research, report that extractions of upper molars and premolars account for roughly 48% to 80% of persistent openings, with the first and second molars most often involved.
Signs that the socket has opened into the sinus
Some openings are found by the dentist on the day, before you leave the chair. Others become obvious at home over the following days. The reviews by Dipalma and colleagues (Diagnostics, 2025) and Alomari and colleagues describe these signs:
- liquid passing from the mouth into the nose, often noticed when drinking or swallowing
- air moving between the socket and the nose, or a feeling of air escaping in the mouth
- a change in how your voice sounds
- a blocked nose, or discharge from the nostril on that side
- pain or discomfort around the area, or bad breath
Please do not test it by pinching your nose and blowing. Dentists sometimes use that manoeuvre, carefully, to confirm an opening, but Alomari and colleagues note it must be used with caution because the pressure can enlarge the opening or push debris into the sinus.
Protecting the clot while it heals
The reviews give similar advice on pressure: anything that pushes air hard through the nose and sinus, or creates suction in the mouth, can disturb the clot. While the opening is healing, Dipalma and colleagues list these as things to avoid:
- blowing your nose (wipe it gently instead)
- sneezing with your mouth closed (sneeze with it open)
- drinking through a straw
- hard physical exertion
Alomari and colleagues also advise against smoking, which slows healing of the gum. Your dentist may prescribe medicines such as antibiotics or a nasal decongestant, depending on the size of the opening and the state of the sinus. Take only what you are prescribed, and ask before stopping anything you already take.
Size and time decide what is done
The reviews agree on the principle and differ a little on the numbers. Very small, fresh openings with no sinus infection are usually managed without surgery, by protecting the clot. Larger openings are usually closed with a minor procedure, ideally soon after they are found, and sometimes at the time of the extraction. Alomari and colleagues note that an opening still present after about three weeks often becomes lined with skin-like tissue (epithelium) and is then unlikely to heal without surgery.
| Situation | What the reviews describe |
|---|---|
| Small, recent opening, no sinus infection | Usually managed conservatively with clot protection and precautions. Reviews put the cut-off between about 2 mm and 5 mm. |
| Larger recent opening | Usually closed with a procedure, such as stretching gum from the cheek side over the socket, or using the buccal fat pad for bigger openings. |
| Opening still present after about three weeks | Often lined with epithelium and unlikely to close on its own. The lined tract is usually removed and the opening closed surgically. |
| Opening with a sinus infection | The infection is treated as well as the opening. In some cases a sinus procedure is combined with closure in the mouth. |
Alomari and colleagues describe an opening that fails to close within 48 to 72 hours, and then becomes lined with epithelium, as a fistula. This is one reason early review matters: closing an opening soon after it forms tends to give better results than waiting.
For the closure itself, a network meta-analysis of nine controlled studies, most of them randomised trials, by Oliva and colleagues (Dentistry Journal, 2024) found the buccal fat pad closed openings more reliably, with less recurrence, than either a cheek-side advancement flap or a palatal rotation flap. Which technique suits you depends on the size and position of the opening, and larger or long-standing openings may be referred to an oral surgeon.
On antibiotics after closure, a retrospective study by Bakacak and colleagues (Clinical Oral Investigations, 2026) reviewed 505 patients who had an opening surgically closed at two Amsterdam hospitals. Complications occurred in 11.7% and a persistent opening in 3.6%. Patients given antibiotics afterwards were less likely to have complications, although the authors note that prospective studies are still needed to confirm this.
When to call, and when to get emergency care
Contact the dentist who did the extraction, or an emergency dentist, the same day if drinks come out of your nose, air seems to pass through the socket, or you develop one-sided nasal discharge, cheek pain or a bad taste after an upper extraction.
Healthdirect's guidance on toothache and gum swelling (reviewed February 2026) is also useful here. Get emergency medical care if you have problems breathing or speaking, or swelling around your eye or neck, and call triple zero (000) if you need urgent medical help. See your dentist if you have a fever over 38°C, trouble swallowing, or swelling in your cheek or jaw.
Normal healing has its own milestones, and a sinus opening is only one of the things that can go wrong. Our guides to how an extraction socket heals week by week and to infection compared with dry socket cover the others. A hard, sharp piece in the socket is different again, and is explained in our article on bone fragments after an extraction.
The X-ray before an upper extraction shows the risk
An OPG shows the sinus floor and the upper roots together, and a 3D scan can show their relationship in more detail where they appear to overlap. At Lumi we take OPGs and 3D scans in the practice, so the dentist can look at this before an upper molar or wisdom tooth removal and talk with you about the risk and the precautions beforehand. Our dentists are general dentists, and more complex cases may be referred to an oral surgeon.
Sinus problems can also run the other way, with sinus congestion making upper teeth ache. That pattern is covered in our article on sinus toothache. If an implant is planned later in the same area, the sinus is usually assessed again at that stage, as explained in our guide to bone grafts and sinus lifts.
Common questions
Will a small opening close by itself?
Often, yes, although not always. Rothamel and colleagues found most openings after upper wisdom tooth removal were under 3 mm, and the reviews describe small, uninfected openings being managed without surgery. The dentist still needs to check it, because size is hard to judge from symptoms alone.
Can I fly after an upper extraction if the sinus was opened?
Pressure changes in the sinus can be a concern, so ask the dentist who treated you before booking a flight. The answer depends on the size of the opening, whether it was closed and how it is healing.
Is a sinus opening the dentist's fault?
Not necessarily. It is a recognised risk when a root sits very close to the sinus, and in the studies above it was linked with the tooth's position, root fractures and age. What matters most is that it is recognised and managed early.
Had an upper tooth out and something feels wrong?
If you think a recent extraction socket may have opened into your sinus, call us to arrange an appointment, including an emergency appointment if needed. You can contact us or book online at our practice in Melrose Park.
Sources
- Eberhardt JA, Torabinejad M, Christiansen EL. A computed tomographic study of the distances between the maxillary sinus floor and the apices of the maxillary posterior teeth. Oral Surg Oral Med Oral Pathol. 1992;73(3):345-346. PubMed 1545967
- Rothamel D, Wahl G, d'Hoedt B, Nentwig GH, Schwarz F, Becker J. Incidence and predictive factors for perforation of the maxillary antrum in operations to remove upper wisdom teeth: prospective multicentre study. Br J Oral Maxillofac Surg. 2007;45(5):387-391. PubMed 17161510
- Pourmand PP, Sigron GR, Mache B, Stadlinger B, Locher MC. The most common complications after wisdom-tooth removal: part 2: a retrospective study of 1,562 cases in the maxilla. Swiss Dent J. 2014;124(10):1047-1051. PubMed 25342640
- Dipalma G, Inchingolo AM, Trilli I, et al. Management of oro-antral communication: a systemic review of diagnostic and therapeutic strategies. Diagnostics (Basel). 2025;15(2):194. PubMed 39857078
- Alomari F, Kota MZ, Khan AAG, et al. Clinical decision-making algorithm for the management of oroantral fistula: a comprehensive guide. Saudi Dent J. 2025;37(7-9):59. PubMed 41091334
- Oliva S, Lorusso F, Scarano A, D'Amario M, Murmura G. The treatment and management of oroantral communications and fistulas: a systematic review and network metanalysis. Dent J (Basel). 2024;12(5):147. PubMed 38786545
- Bakacak MM, Ho JPTF, van der Meij EH, Schreuder WH, Lodders JN. The effect of postoperative antibiotics in reducing complications following primary surgical closure of oroantral communications secondary to tooth extraction: a retrospective multicenter study. Clin Oral Investig. 2026;30(10):494. PubMed 42814174
- healthdirect. Toothache and gum swelling. Last reviewed February 2026. healthdirect.gov.au
This article is general information only and is not a substitute for advice about your own situation from a dentist.
