Upper wisdom teeth and your sinus

Most people reading this are trying to understand a risk raised at a consultation. Some are reading it three days afterwards, with water arriving in the nose. The urgent material is first, for the second group. If you have already been treated here, the written post-operative instructions govern and this page is general.

Do not test this yourself by pinching your nostrils and blowing against them. That manoeuvre is the one most capable of turning a small opening into a larger one, and it is done gently, by a clinician watching the socket. Separately, a little blood in the nose on the day of an upper extraction is common and does not by itself mean the sinus is open.

The maxillary sinus is an air-filled space inside the cheekbone, one on each side. It is lined with a thin respiratory membrane and drains into the nose through a small opening high on its inner wall — near the roof rather than the floor, which is part of why an infected sinus tends to stay infected.

The floor of that space is the roof of your upper back teeth. In childhood the sinus is small and sits well above the roots. It enlarges through adolescence and keeps expanding in adulthood, growing downwards and outwards into the bone around the roots of the premolars and molars. The process is called pneumatisation, and how far it goes varies a great deal between individuals and between the two sides of one face.

By adulthood the relationship falls somewhere on a range: a solid plate of bone several millimetres thick at one end, a thin shell in the middle, and at the far end roots projecting into the sinus outline, tented under its lining, with no bone between the two at all. Two things push a mouth along that range — long-standing infection at the end of a root, which erodes the sinus floor from below, and a missing upper tooth, because the sinus expands into the space it left. An upper third molar beside a gap of many years can be sitting against a sinus that has come down to meet it.

What the films can and cannot tell you

A panoramic radiograph shows the sinus floor as a white line above the upper teeth. Where that line dips between the roots, disappears across a root end, or appears to be crossed by a root, the relationship is close. That is the finding mentioned at a consultation, and it is one reason upper and lower third molars are consented as separate propositions rather than as a set of four.

The limitation is the one that applies to lower teeth and the nerve canal. A panoramic film is a flattened two-dimensional image of a curved structure, so things that overlap on it are not necessarily touching. A cone-beam scan resolves that where the answer would change the plan, and if one is recommended you can ask which question it is expected to answer.

None of this predicts what will happen to you. A root sitting inside the sinus outline can be removed with the floor intact, and an opening occasionally occurs where the film looked unremarkable. What the imaging changes is how the tooth is approached, and what you are told beforehand.

Antrum is an older word for the maxillary sinus, and it survives in the name. An oro-antral communication is an opening between the mouth and that sinus, through the floor of the empty socket. Nothing is visible from outside. In most cases it is a few millimetres across, at the very bottom of a socket that is itself around a centimetre deep.

Two structures have to be breached for it to exist: the thin plate of bone forming the sinus floor, and the lining resting on it. Where the bone comes away with the tooth but the lining stays intact, there is a bone defect and no communication, and it generally heals without anything further being needed. That distinction is one reason a socket that looks alarming on the day can turn out to need nothing.

How it is found at the time

The socket is inspected once the tooth is out. Bone at the floor of a socket has a particular look, an opening does not have it, and often the lining or the dark space above it can be seen directly. Blood that bubbles in time with breathing is the other direct sign. Where there is doubt, you are asked to pinch the nostrils and breathe out softly while the socket is watched. The word doing the work is softly: a forceful version can tear a lining that was intact, or enlarge a small opening.

Probing is the other thing not done. Pushing an instrument or a suction tip into the depth of an upper molar socket is capable of creating the opening it was looking for.

Three situations that get confused with each other

• A communication is an opening present at or shortly after the extraction, with raw tissue around it. This is the one that commonly closes on its own, or with a procedure at the same visit.
• A fistula is a communication that has stayed open long enough — a matter of weeks — to line itself with epithelium. It is a permanent tract, it does not close spontaneously, and it is closed surgically.
• A root or tooth fragment displaced into the sinus is a separate problem that may or may not come with a communication. It is confirmed on a film and retrieved, sometimes with an ENT clinician involved. Uncommon.

Small openings recognised at the time of surgery commonly close without further surgery, and the mechanism is the blood clot. A stable clot filling the socket is the scaffold across the defect, and the lining and the gum edges heal over it from both directions. Everything in the sinus precautions exists to leave that clot where it is.

Size is the main determinant. A small opening is generally managed by protecting the clot: a suture or two drawn across the socket to hold the gum edges together, precautions for a set period, and medication where the sinus needs settling. Past a certain size the defect is unlikely to bridge on its own, and it is closed at the same visit with a flap of gum drawn across and sutured. Where that line falls is a matter of a few millimetres, judged at the chair against the state of the tissue and of the sinus rather than against a number alone.

Size is not the whole answer. A sinus that was already infected heals less predictably than a healthy one. Smoking works against it twice over, through the suction and through the effect of nicotine on the small vessels supplying the site. A clot lost to a straw, a nose blow or a vigorous rinse takes the scaffold with it. How closely the instructions are followed genuinely changes the outcome here, in a way that is not true of every item on a post-operative sheet.

Nobody can tell you in advance that yours will close. What can be said is that where an opening is small, recognised at the time, managed at that visit and protected afterwards, closing without further surgery is the usual course. And where it has not closed, the sign is not subtle: fluid or air moving between the mouth and the nose.

Almost every instruction on the sinus list comes from one mechanism, a pressure difference across the socket. While a communication exists, anything that raises pressure in the nose drives air down through the defect and lifts the clot out from above; anything that lowers pressure in the mouth pulls it out from below. Both destroy the same clot, which is why you can work out the items the list did not think of: blowing hard, straining against a closed throat, sucking.

Do not blow your nose

Nose blowing generates the highest nasal pressure of anything most people do in an ordinary day, and it is directed exactly where you do not want it. The air has nowhere to go except through the drainage opening into the sinus, and from there the shortest route out is through the socket. This is the instruction most capable of undoing the surgery, and the one people break by reflex. Dab and wipe rather than blow.

Congestion on that side is common after an upper extraction, because the lining swells, and the reflex it produces is the one thing you must not act on. If it troubles you, ask what you may use. Something to reduce swelling in the lining is often part of the plan, and what is appropriate depends on your medical history and the rest of your medication.

Sneeze with your mouth open

A sneeze cannot always be suppressed. What can be controlled is where the pressure goes: with the mouth open the blast vents forwards, and with the mouth shut it is forced through the nose at considerable pressure. Pinching the nose to stifle a sneeze is the worst version of all, because it traps the pressure inside the space you are protecting. Mouth open, no attempt to hold it in, no hand clamped over the nose. Cough the same way.

No straws, no spitting, no smoking, no vaping

These are the negative-pressure half of the problem. Drawing on a straw, a cigarette or a vape creates suction capable of pulling a young clot out of a socket. Vigorous rinsing and spitting apply shearing force across the same clot, so let a salt-water rinse fall out of the mouth. Smoking has a second effect independent of the suction, because nicotine constricts the small vessels supplying the site, and vaping is not a workaround for either mechanism.

Flying, diving, altitude and wind instruments

A healthy sinus equalises with the outside world through its drainage opening as ambient pressure changes. A sinus whose lining is swollen after surgery equalises poorly, so a pressure difference builds across its walls — and one of those walls, at the moment, is your socket. Descent is the phase of a flight when the difference is greatest. Diving is the same physics with far larger numbers, and it adds deliberate forceful equalisation, the exact manoeuvre these precautions exist to prevent. Brass and woodwind playing generates sustained pressure against a closed system, as does blowing up balloons.

There is no general interval that covers this, and an article is the wrong place to get one. The interval is set against what was found at your surgery and what was done about it. If you have a flight booked, a dive planned, an audition, or work involving pressure, say so before the surgery is scheduled, because it may change the date rather than the instructions.

The rest of the list, and why

• Sleep with the head raised for the first few nights. Lower venous pressure at the site means less oozing and less swelling in the lining.
• Do not rinse at all for the first twenty-four hours, then rinse gently, letting the water fall out; early rinsing disturbs a clot that has not organised.
• Leave the socket alone — not the tongue, not a finger, not a toothpick, and not an irrigating syringe unless you were given one for that site.
• Take any antibiotic you were prescribed to the end of the course, and use anything prescribed for the nose exactly as the written instructions say. The doses are on that sheet, not in this article.
• Do not test whether it has closed. Testing is the thing that reopens it.

How long each precaution runs comes from your written instructions, not from this page. The shape of it is that the pressure precautions outlast the mouth-care ones, and that smoking is worth extending past whatever date you are given.

The signs are specific, which is useful, because it means you are not being asked to interpret vague sensations. An opening between the mouth and the sinus produces things that do not otherwise happen.

• Fluid going the wrong way: a mouthful of water arriving in the nose on that side. The sign reported most often, and the most reliable.
• Air going the wrong way: air moving over the socket as you breathe, or escaping into the mouth as you speak.
• A whistling from the back of the mouth, sometimes noticed by someone else first.
• Discharge from one nostril and not the other, particularly if it smells unpleasant.
• A persistent bad taste on that side that a gentle salt-water rinse does not shift.
• An inability to draw on anything, or to whistle.
• Dull pressure in the cheek below the eye, worse on bending forward.

Not all of them mean the same thing. The first four are close to specific for an opening. The last two also occur with an ordinary sinus infection unrelated to your surgery, and with a lining that is simply swollen after an extraction. That distinction is made by examining the site, so report what you noticed and let it be sorted out in the chair.

The shape of the timeline helps as well. An opening that is going to close does so quietly, and the marker is the absence of these signs rather than the presence of anything. Signs that appear on day one and are settling by day three are usually swelling. Signs that appear on day four and are still there on day ten are not.

Where an opening persists, two things happen in sequence, and both are the argument against waiting. The sinus becomes colonised by mouth bacteria and develops an infection that will not clear while the opening is there, and the tract lines itself with epithelium and loses the ability to close on its own. Neither is an emergency. Both make the eventual repair a larger operation than the one that would have worked in the first week.

A persisting communication is assessed rather than assumed: the site examined, the size and state of the surrounding tissue recorded, and imaging taken where there is a question about the sinus itself or a fragment inside it.

The order of operations matters. A flap of gum closed over a sinus that is actively infected tends to fail, because pressure and discharge push against the repair from above. So an infected sinus is treated first or alongside: an antibiotic chosen against your full medication list, something to reduce swelling in the lining, sometimes a steroid nasal spray. Where the sinus disease is established, a physician or an ENT clinician is involved rather than the dental side being managed alone.

The closure itself is a soft-tissue operation. The commonest design mobilises the gum on the cheek side, advances it across the defect and sutures it to the tissue on the palatal side, with the suture line deliberately resting on sound bone rather than over the hole. Other designs are used depending on where the defect sits and how much tissue is available. What is used to keep you comfortable for it is agreed beforehand, as it is for the extraction. Afterwards the same precautions apply again, and matter more the second time.

Two things to be clear about. This is a further operation, with its own swelling, recovery and sutures, and calling it soft-tissue work rather than bony work does not make it nothing. And most repairs hold at the first attempt, with a second procedure occasionally needed. Neither point changes the recommendation, because an opening left in place does not improve with time.

Where a root fragment has gone into the sinus it is retrieved, and retrieval is planned from a film rather than attempted through the socket by feel, because fishing through a small opening enlarges it. A very small, deep fragment with an intact lining and no infection is occasionally the exception, and where leaving it is the more proportionate choice that is decided with you and written down.

Who carries out each part of this is settled when it is planned, and you are told then. This practice treats third molars. Managing a communication that follows a third molar removal sits inside that; treatment of the sinus itself does not, and goes to a physician or an ENT clinician, with the referral made from here.

Everything above describes a risk belonging to upper third molars specifically. It sits alongside a set of features that generally make the upper side the more straightforward removal. Both are true at once.

The difference starts with the bone. The upper jaw is largely trabecular, a fine lattice inside a thin outer shell, with some elasticity to it; the lower jaw at the third molar is dense cortical bone, thickest exactly where that tooth sits. So an upper socket can often be expanded and the tooth delivered along its own path, where a lower one frequently has to be cut. Most of the other differences follow: less bone removal, the tooth divided less often, and less swelling and jaw stiffness, because the muscles that close the jaw overlie the lower field and not the upper one. Dry socket, the commonest complication of a lower third molar socket, is uncommon in an upper one. Neither the inferior alveolar nerve nor the lingual nerve is anywhere near an upper third molar, so numbness of the lip, chin or tongue is not a feature of upper wisdom tooth removal.

Numbness of the cheek and lip on the day is expected from the local anaesthetic and wears off with it. Any numbness still present the following morning is reported the same day, whichever tooth it followed, and is not something to hold until a review appointment.

The counterweights are the sinus and two others belonging to the same anatomy. The tuberosity is the bulb of bone at the very back of the upper jaw; it is thin-walled and can fracture away with the tooth if force goes in the wrong direction, and it is most vulnerable in an older jaw and around a lone-standing upper third molar with nothing biting against it. Separately, a tooth sitting high and far back can be displaced backwards into the space behind the jaw. Both are uncommon, and both are why an upper third molar is planned from a film rather than assumed to be simple.

Some of this is anatomy you were born with and some of it is not.

What the film and the history change

• Roots projecting into the sinus outline, or a sinus floor that dips down between them.
• Divergent, bulbous or hooked roots, which take bone with them if they are forced along a single path.
• A large, well-pneumatised sinus, particularly where an upper tooth has been missing on that side for years.
• Long-standing infection at a root end, which erodes the sinus floor before the surgery starts.
• Age: roots are fully formed and the bone less forgiving in the fourth decade and beyond.
• Existing sinus disease, chronic congestion or nasal allergy, which make the lining heal less predictably.

What the operation does about it

The plan is built around not pushing the tooth upwards. Bone is removed from the cheek side to create a path of withdrawal rather than the tooth being levered from below; diverging roots are divided so each comes out along its own path; force is not directed towards the sinus. Afterwards the socket is not curetted blindly, because that can tear a lining that survived the extraction. Where a small fragment is deep, the lining looks intact and there is no infection, removing it can carry more risk than leaving it — a judgement made at the time, explained to you and recorded.

What you can change

Stopping smoking, for as long a period either side of the surgery as you can manage, is the modifiable factor that matters most. Following the precautions is the second. The third is saying in advance that there is a flight, a dive, an instrument or physical work in the diary, so the timing is set against your life rather than against a general rule.

Whether the sinus was involved is something you are told, not something to deduce. Before you leave the building after an upper third molar removal you are told whether the sinus floor was opened, what was done about it, and what the instructions are for your case. If sutures were placed to support the socket you are told that too, because it changes what your tongue will find.

The written post-operative instructions govern. Where they differ from this page on the length of the precautions, on medication, or on the interval before flying, follow the sheet: it was written against your findings and this page was not.

Questions worth asking before you leave

1. Was the sinus opened, and if so, roughly how large was the opening?
2. Was anything done to close it, or is it being left to close on its own?
3. How many days do the sinus precautions run, and what tells you they can stop?
4. When may I fly, dive, swim underwater, or play a wind instrument?
5. What exactly should I call about, and what counts as the same day rather than the next appointment?
6. Which number do I call outside opening hours, and where should I go if I cannot reach anyone?

Press on that last one rather than accepting a general answer. The signs of an opening that has not closed appear at home, often in the evening, and the useful answer is a number and a fallback.

Two of these are worth asking before the surgery as well. If the consultation established that the roots sit against or into the sinus floor, ask what that means for anything already in your diary. Rearranging a flight before a date is set is an inconvenience; finding the conflict on the morning of surgery moves the surgery.