Back Tooth Hurting and Gum Swollen? What It Usually Means and What to Do
A sore back tooth with a swollen gum usually needs a dentist's look within a few days, and sometimes the same day. The cause is most often one of five things: a wisdom tooth coming through, food trapped under the gum, gum disease, an infection at the root of the tooth, or a cracked tooth.
Let me explain what each one feels like, what you can do tonight, and the few signs that mean the ER and not a dentist. The list below is a practical starting point, not a diagnosis.
The short version
• Most often it is a wisdom tooth coming through, trapped food, gum disease, an infection at the root, or a cracked tooth. Sinus pressure can also ache in the upper back teeth.
• Tonight: rinse with warm salt water, clean gently, hold a cold pack on your cheek, and take pain relief only as the package says.
• Call a dentist today for a throbbing tooth, a bump on the gum or a swollen cheek. Go to the ER or call 911 for trouble breathing or swallowing, or swelling that spreads, especially with a fever.
Written by Dr. Gloria Jung, DDS, BSc, at Dentudio Dentists in Richmond. Reviewed on 2 October 2026 against Cleveland Clinic, NIDCR, MyHealth Alberta, NHS and BC Centre for Disease Control guidance, listed at the end of this post.
Why does my back tooth hurt and my gum feel swollen?
Because the gum around that tooth is irritated or infected, and something is causing it. These are the usual causes, with how urgent each one is and what fixes it.
Likely cause | What it feels like | How urgent, and the fix |
A wisdom tooth coming through | Puffy gum flap, bad taste | Call this week. Cleaning, or removal |
Food under the gum | Sore spot by one tooth | Often settles in 1 to 2 days. Gentle cleaning |
Gum disease or a gum abscess | Red, bleeding gums, or a bump | This week, today if a bump. Deep cleaning |
A tooth abscess | Throbbing, worse biting | Call today. Root canal or removal |
A cracked tooth or cavity | Sharp pain biting or with cold | Call this week. Filling, crown or root canal |
Sinus pressure | Ache in the upper teeth, face pressure | Not dental. See your doctor |
Age changes the order. MyHealth Alberta says wisdom teeth usually come in between ages 17 and 21, that most wisdom tooth problems affect people between 15 and 25, and that people older than 30 usually do not have wisdom tooth problems that need removal. So in your late teens, twenties and early thirties, the first row is the one I think of first. After that, gum disease and tooth problems move up.
Where each cause sits. The same information is in the table above.
Can a wisdom tooth make the gum behind it swell and hurt?
Yes, and it is the classic cause of a swollen gum at the very back of the mouth. When a wisdom tooth comes through only part of the way, a flap of gum (called an operculum) can stay over part of the tooth. Food and bacteria get trapped under that flap, and the result is pericoronitis, which is inflammation of the gum around a wisdom tooth, according to Cleveland Clinic (updated 20 April 2026).
Cleveland Clinic lists the signs as redness and swelling of the gum, severe pain around the back teeth, pus or drainage, discomfort when swallowing, facial swelling and a stiff jaw that is hard to open. Milder, longer-lasting cases bring a mild ache, bad breath and a bad taste. It is more likely around the lower wisdom teeth, though the upper ones can be affected too.
Will it go away on its own? It may. Sometimes it happens briefly while the tooth is coming through, and a dentist may simply keep an eye on it. But Cleveland Clinic warns that untreated pericoronitis can become serious if the infection spreads, which is why it says to see a dentist instead of hoping it improves.
What fixes it depends on how inflamed it is. Cleveland Clinic lists a cleaning that flushes out the trapped food and bacteria, antibiotics, a prescription mouthwash, a short procedure to remove the gum flap, and removal of the wisdom tooth if it keeps causing trouble. Our page on wisdom teeth removal in Richmond explains what to expect if it comes to that.
Could food stuck under the gum cause a swollen gum and sore tooth?
Yes, and it is the easiest cause to fix. A husk, a seed or a hard crumb can wedge beside a back tooth and the gum swells around it. Cleveland Clinic gives a popcorn hull stuck in the gums as its example, and says temporary gum irritation should go away on its own in a day or two.
That two-day mark is useful. If a sore, swollen patch has not clearly improved after two days, something more than a stray crumb is going on, and it is time for a dentist to look.
Could gum disease cause a swollen gum around one back tooth?
Yes. Gum disease is an infection of the tissues that hold your teeth in place, and NIDCR (last reviewed August 2026) lists red, swollen or tender gums that bleed easily among its signs. It starts with plaque, the sticky film of bacteria on your teeth, and if it is left alone it can spread to the bone that supports the teeth.
It can also show up as a gum abscess, which Cleveland Clinic calls a periodontal abscess: a pocket of infection in the gum that looks like a boil or pimple. The most obvious sign is a swollen bump on the gum, and some people feel pain or tenderness while others do not.
One honest point: early gum disease (gingivitis) usually does not hurt, which is why MyHealth Alberta says many people delay treatment. A swollen gum that does hurt is worth having looked at sooner, not later. A dentist or hygienist measures the pockets around the tooth and takes an x-ray to check for bone loss, and the usual fix is a deep cleaning called scaling and root planing, according to NIDCR.
Could a tooth abscess or a cracked tooth be the reason?
Yes, and an abscess is the one I would not leave alone. A tooth abscess is a pocket of pus from an infection. It forms at the root tip when bacteria get into the tooth through a deep cavity or a crack, according to Cleveland Clinic (updated 22 January 2026). MyHealth Alberta lists the signs: throbbing pain that is worse when you chew, red swollen gums, a bad taste, swelling in the jaw or face, a fever, and a red, swollen bump that may ooze blood or pus.
"But Dr. Jung, the pain stopped, so I am fine, right?" Not necessarily. Cleveland Clinic explains that the pain can stop because the infection has killed the nerve inside the tooth, but the bacteria keep spreading and destroying the tissue around it. The NHS (last reviewed 18 March 2026) says plainly that a dental abscess will not go away on its own.
Antibiotics alone do not fix it either. The BC Centre for Disease Control tells dentists that drainage is the best treatment for a localized abscess, because it relieves the pressure and removes the pus, and that antibiotics are only needed when there are signs of a wider problem, such as a fever. Cleveland Clinic says antibiotics may help with the remaining bacteria but will not remove the cause of the infection, which is the tooth. The usual fix is draining the pus, then a root canal to save the tooth or removal of the tooth, as the NHS and MyHealth Alberta both describe. Our root canal page explains how a root canal saves an infected tooth.
A cracked tooth or a deep cavity is the usual way bacteria get in. Cleveland Clinic says a sharp, stabbing pain can mean a cavity or a crack, and MyHealth Alberta says moderate to severe sensitivity can mean a cracked tooth, a cavity or a lost filling. If bacteria reach the nerve, Cleveland Clinic says a root canal is needed.
Can sinus pressure feel like a toothache in my upper back teeth?
Yes. Cleveland Clinic says sinus pressure commonly refers pain to the teeth, especially around the upper molars, and that it can also feel like tightness or achiness around the eyes, nose and cheekbones. Because it names the upper molars, pain in a lower back tooth is more likely to be a problem in the mouth.
If your upper back teeth ache along with pressure in your face, and the gum looks normal, think about your sinuses. A dentist can check the teeth and gums and take an x-ray first. If the teeth are healthy, your doctor can look at the sinuses.
What can I do tonight for a sore back tooth and swollen gum?
Rinse with warm salt water, clean gently around the area, hold a cold pack to your cheek, and take pain relief only as the package directs. None of this fixes the cause, but it takes the edge off until a dentist can.
Rinse gently with warm salt water. Mix 1 teaspoon (5 mL) of salt in 1 cup (250 mL) of warm water, the mix MyHealth Alberta gives, and swish gently three to four times a day, as Cleveland Clinic suggests.
Clean the area gently. Use a soft toothbrush along the gumline, as the NHS advises, and clean between your teeth once a day.
Hold a cold pack on the outside of your cheek, 15 to 20 minutes at a time. MyHealth Alberta says not to use heat.
Take pain relief only as the package directs. Cleveland Clinic lists acetaminophen or ibuprofen. The dose is on the package, and more is not better: the NHS warns that a higher dose will not work better and can be very dangerous.
Eat soft foods, and skip very hot or very cold food and drink, as the NHS advises.
Do not put aspirin on the gum. MyHealth Alberta says it can damage your gums.
Sore back tooth and not sure it can wait?
Same-day and walk-in visits are subject to availability, so call first. Open 9am to 5pm, seven days a week.
Is a swollen gum around a back tooth an emergency, or can it wait?
It depends on what else you notice. A gum that is mildly sore and improving can wait a few days for an appointment. A throbbing tooth, a bump on the gum or a swollen cheek should be seen today. A few signs mean the ER.
What you notice | What to do |
Mild soreness and puffiness, easing over a day or two | Home care tonight. Book an exam this week if it comes back or is still there after 2 days |
A gum that keeps swelling around the same back tooth | Book an exam this week |
A throbbing tooth, pain when you bite, a pimple-like bump, a bad taste | Call us today |
A swollen cheek that is not spreading | Call us today |
Trouble breathing or swallowing, or spreading swelling with a fever | ER or 911 |
Four levels of urgency. The same information is in the table above.
When is a swollen gum an ER visit and not a dentist visit?
When the swelling is spreading or threatens your breathing, go to the ER or call 911 instead of waiting for a dentist. Cleveland Clinic, the NHS and MyHealth Alberta between them name these signs:
Trouble breathing, speaking or swallowing.
Swelling that spreads toward your eye, jaw or neck, or a swollen or painful eye, or sudden trouble with your eyesight.
A fever of 38 C (100.4 F) or higher, or confusion or a fast heartbeat, with a sore tooth or swollen gum.
A mouth you can barely open, or a lot of swelling inside your mouth.
Tooth or jaw pain with chest pressure or shortness of breath. MyHealth Alberta lists a heart attack among the causes of pain that is referred into the teeth or jaw, so this one is a 911 call.
Do not drive yourself: ask someone to drive you, or call 911, as the NHS advises. Once you are safe, the tooth still needs a dentist, because an abscess will not clear up on its own. Our dental emergency page lists what else counts as an emergency.
Swollen gum that hurts? Phone us today.
Same-day and walk-in visits are subject to availability, so call first (604-370-1450). Open 9am to 5pm, seven days a week, Saturday and Sunday included. For planned visits, use the Book Online button at the end of this post.
What will a dentist do about a swollen gum at the back of my mouth?
Find the cause, relieve it, then fix it, in that order. Here is how that goes at Dentudio.
An exam and an x-ray. We look at the gum and the tooth, and we take an x-ray, because the picture shows what the gum hides: the roots, the bone and any wisdom tooth that is only partly through. MyHealth Alberta says x-rays show whether wisdom teeth are causing problems, and Cleveland Clinic says dentists check the roots and rule out cavities. We use digital x-rays.
Relief first. Flushing out a gum flap, or draining an abscess, takes the pressure off quickly. The BC Centre for Disease Control says drainage gives immediate relief from pressure and pain.
Then the fix, matched to the cause. That might be a cleaning under the gum, a filling for a cavity or a crack, a root canal for an infected tooth that can be saved, or wisdom tooth removal when a wisdom tooth keeps causing trouble. We list root canal treatment and wisdom teeth extractions on our Google profile at the time of writing. Whether your particular wisdom tooth is a straightforward one is something the x-ray tells us, and we will say so plainly.
Not every swollen gum needs antibiotics, and they never replace treating the cause. The BC Centre for Disease Control notes that dentists in BC write about 18 percent of the province's community antibiotic prescriptions, which is one reason its guidance asks dentists to use them only when they are needed.
Back tooth trouble in Richmond: how to reach Dentudio
A few practical things, since people ask them at the front desk:
Phone first. Call 604-370-1450. We are open 9am to 5pm, seven days a week, Saturday and Sunday included. Same-day and walk-in visits are subject to availability, so call first; for planned visits, use the Book Online button.
We are easy to find. Dentudio Dentists is at 145-5555 Gilbert Road in Richmond, at the corner of Gilbert and Lansdowne, three blocks west of Lansdowne Canada Line station. Parking on site is free.
Patients write about us. We have 4.9 from 573 Google reviews at the time of writing. Google's review topics for the clinic show "gentle dentist" in 17 reviews and "wisdom teeth removal" in 8.
We speak your language. I speak English, Korean and Mandarin, and our team also serves patients in Chinese and Korean.
Coverage questions are welcome. Our front desk can check your coverage before any treatment, and we accept the CDCP. If you are wondering what MSP covers, our guide to dental insurance in BC explains.
Frequently asked questions
Can a swollen gum go away on its own?
Sometimes. Gum irritation from a trapped crumb or a hard bite should settle by itself in a day or two, according to Cleveland Clinic, and a mild case of pericoronitis may only be monitored. But a tooth abscess will not go away on its own, and the pain can stop while the infection carries on. If it has not clearly improved in two days, have a dentist look.
Is a swollen gum around a back tooth an emergency?
Not always, but some versions are. A mildly sore, puffy gum that is easing can wait a few days. A throbbing tooth, a bump on the gum or a swollen cheek means call a dentist today. Trouble breathing or swallowing, swelling spreading toward the eye, jaw or neck, a fever, or a mouth that will not open means the ER or 911.
What helps a swollen gum around a wisdom tooth at home?
Rinse gently with warm salt water (1 teaspoon of salt in 1 cup of warm water) a few times a day, clean the area with a soft toothbrush, and hold a cold pack on the outside of your cheek for 15 to 20 minutes at a time. Take pain relief only as the package directs. Do not put aspirin on the gum, and do not use heat.
Can a swollen gum around a wisdom tooth be treated without pulling the tooth?
Sometimes. Cleveland Clinic lists a cleaning that flushes out food and bacteria, antibiotics, a prescription mouthwash, and a short procedure to remove the gum flap, with wisdom tooth removal if it keeps causing trouble. Mild cases may only be watched. The exam and x-ray tell your dentist which of these suits your tooth.
Will antibiotics fix a swollen gum and a sore back tooth?
Not on their own. For a localized tooth abscess, BC Centre for Disease Control guidance says drainage is the best treatment and antibiotics are only needed with signs of a wider problem, such as a fever. Cleveland Clinic adds that antibiotics will not remove the cause, which is the infected tooth. Your dentist decides whether you need them as well as treatment.
Can sinus pressure cause pain in my upper back teeth?
Yes. Cleveland Clinic says sinus pressure commonly refers pain to the teeth, especially the upper molars, and it can also feel like tightness around the eyes, nose and cheekbones. If your upper back teeth ache with facial pressure and the gum looks normal, think about your sinuses. A dentist can check the teeth first, and your doctor can take over if they are healthy.
Why is my gum swollen around only one tooth?
A swelling around a single tooth usually points to a local cause: food trapped under the gum, a partly erupted wisdom tooth, a pocket of gum disease, or an infection at the root. Cleveland Clinic says a gum abscess often shows as a boil-like bump. Swelling in one spot that keeps coming back, or comes with throbbing pain, needs an exam and an x-ray.
Call us about your back tooth in Richmond
Your gum has told you where the problem is, so let us go and find out why! If it hurts, phone us first and we will tell you how soon we can see you.
Planned visit and not an emergency?
Same-day and walk-in visits are subject to availability, so call first (604-370-1450); for planned visits, use the Book Online button.
Dentudio Dentists, 145-5555 Gilbert Road, Richmond, BC. Open 9am to 5pm, seven days a week. 4.9 from 573 Google reviews at the time of writing.
Sources: Cleveland Clinic, Pericoronitis (updated 20 April 2026), Tooth Abscess (updated 22 January 2026), Periapical Abscess (updated 29 July 2026), Periodontal Abscess (updated 5 January 2023), Toothache (updated 11 April 2023) and Sinus Pressure (updated 9 February 2023); NIDCR, Periodontal (Gum) Disease (last reviewed August 2026); MyHealth Alberta, Wisdom Tooth Problems, Abscessed Tooth, and Toothache and Gum Problems (Healthwise, current as of 31 July 2024); NHS, Dental abscess (last reviewed 18 March 2026); BC Centre for Disease Control, Antimicrobial Stewardship in Dentistry (read 2 October 2026). Review count, review topics and services listed on the Google Business Profile, 2 October 2026.
Dr. Gloria Jung, DDS, BSc
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