Why Is My Gum Swollen Around One Tooth in the Back?
I had all four wisdom teeth out when I was 19. One of the sockets in the back got infected. I ran a fever and ended up on antibiotics and Tylenol. So when someone asks, “Why is my gum swollen around one tooth in the back?” I don’t brush it off. Sometimes it’s a piece of popcorn. Sometimes it’s an infection that needs a dentist. Here’s how to tell the difference, based on what dental experts say.
This article is for general information and isn’t medical advice. If you’re in pain or have a fever, call your dentist.
The Short Answer
Swelling around one back tooth usually has a local cause. The most common ones are:
- A wisdom tooth coming in or partially trapped under the gum
- Food stuck under the gumline
- Gum disease
- An abscess, which is a pocket of infection
- Healing problems after a tooth was pulled
Some of these clear up with good cleaning in a day or two. Others won’t go away without treatment. The rest of this post explains each one.
1. A Wisdom Tooth (Pericoronitis)
If the swelling is at the very back of your mouth, a wisdom tooth is a top suspect. According to the Cleveland Clinic, “pericoronitis is swelling of the gum tissue around your wisdom teeth.” It usually happens when a wisdom tooth is only partly through the gum.
Here’s why. A partially erupted tooth often has a flap of gum over part of it. The Cleveland Clinic explains that “food, bacteria and debris can get trapped underneath” that flap. That leads to swelling and infection.
Pericoronitis is most common in people in their 20s. It affects the lower wisdom teeth most often.
Signs to watch for:
- Pain around your back teeth
- Red, puffy gum over or around a wisdom tooth
- Bad breath or a bad taste
- Pus
- Trouble opening your mouth all the way
- Fever or facial swelling in more serious cases
What helps: The Cleveland Clinic lists warm saltwater rinses, antibacterial mouthwash, over-the-counter pain relievers and careful brushing and flossing as home care. A dentist may clean the area, prescribe antibiotics or a chlorhexidine rinse, remove the gum flap or take the tooth out. With treatment, the Cleveland Clinic says pericoronitis “usually goes away within a week or two.”
If the same wisdom tooth keeps flaring up, ask your dentist whether it should come out. You can read more about impacted teeth from the Cleveland Clinic.
2. Food Stuck Under the Gum
This is the most harmless cause, and a common one. Back teeth do most of the chewing. They also have deep grooves and tight spaces. A popcorn hull, a seed or a sharp chip can slide under the gumline and get stuck.
Popcorn is a classic culprit. Dental journals have even written up cases of gum abscesses caused by popcorn hulls.
What to try:
- Floss gently on both sides of the tooth. Curve the floss around the tooth and slide it just under the gumline.
- Rinse with warm salt water.
- Brush gently with a soft-bristled toothbrush.
Don’t dig at your gum with a toothpick, a pin or your fingernail. That can push the food deeper or cut the gum.
If the swelling goes down within a day or two after the food comes out, that was likely the problem. If you can’t get it out, or the swelling gets worse, see your dentist. A trapped piece of food can turn into an infection.
3. Gum Disease
Gum disease can show up in one spot first, especially in the back where it’s hard to clean. The early stage is gingivitis. The more serious stage is periodontitis.
According to the Cleveland Clinic, gum disease starts with bacteria and plaque along the gumline. Common signs include red, swollen or tender gums, bleeding when you brush or floss, bad breath and gums that pull away from your teeth.
Gum disease is common in adults. Healthline notes that the CDC has estimated nearly half of U.S. adults 30 and older have some form of it.
What helps: Brush twice a day, floss daily and keep up with dental cleanings. Early gum disease can often be reversed. Advanced gum disease needs professional treatment, such as a deep cleaning.
4. An Abscess
An abscess is a pocket of pus caused by a bacterial infection. There are two main kinds that cause swelling around one tooth.
A periodontal (gum) abscess starts in the gum. According to the Cleveland Clinic, the main sign is “a swollen bump on your gums.” You might also have a toothache, pain when chewing, bad breath, a loose tooth or a fever.
A tooth abscess starts inside the tooth, often from deep decay or a crack. The Cleveland Clinic describes the pain as “shooting, throbbing or like it’s radiating to your ear, jaw or neck.”
This is the key point: an abscess doesn’t heal on its own. The Cleveland Clinic says “you can’t treat a periodontal abscess at home.” Treatment may include draining the abscess, a deep cleaning, antibiotics, a root canal or pulling the tooth.
A saltwater rinse can make you more comfortable while you wait for your appointment. It won’t cure the infection.
5. Healing Problems After a Tooth Was Pulled
If you recently had a back tooth or wisdom tooth removed, swelling nearby could be part of healing. Some swelling in the first few days is normal. Swelling or pain that gets worse instead of better is not.
This is what happened to me. I had all four wisdom teeth out at once, and one of the sockets got infected. I had a fever and needed antibiotics. My advice is simple. If your swelling or pain is increasing after an extraction, or you run a fever, call your oral surgeon. Don’t wait it out.
Recovering from wisdom teeth removal right now? Here’s what to know about how long after wisdom teeth removal you can eat a burger, plus the signs of dry socket and infection.
When to See a Dentist
Call your dentist if:
- The swelling lasts more than a day or two
- You see a bump or pimple-like spot on your gum
- You have pus or a bad taste that won’t go away
- The pain is throbbing or spreading to your ear, jaw or neck
- The tooth feels loose
- It hurts to chew
When to Go to the Emergency Room
The Cleveland Clinic says to go to the ER right away if you have a tooth abscess along with:
- A fever of 100.4°F or higher
- Confusion
- Trouble swallowing
- A fast heart rate
- Facial swelling
Swelling that spreads to your face, jaw or neck, or any trouble breathing or swallowing, is an emergency.
What You Can Do at Home Right Now
While you wait for an appointment, these steps can help you feel better:
- Rinse with warm salt water. Swish gently a few times a day.
- Floss carefully around the tooth to clear out any trapped food.
- Brush gently with a soft-bristled brush.
- Take an over-the-counter pain reliever as directed on the label, if it’s safe for you.
- Skip hard, crunchy and very hot foods on that side.
Home care can calm things down. It can’t fix an infection or a trapped wisdom tooth. If it isn’t clearly improving, get it checked.
Frequently Asked Questions
Why is my gum swollen around one tooth in the back?
Common causes are a wisdom tooth coming in, food stuck under the gum, gum disease, an abscess or problems healing after an extraction. If it doesn’t improve within a day or two, see your dentist.
Can a swollen gum around one tooth go away on its own?
Sometimes. If trapped food caused it, the swelling may go down once the food is out. An abscess won’t go away on its own and needs treatment.
Is swelling around a wisdom tooth serious?
It can be. Pericoronitis is an infection of the gum around a wisdom tooth. It often responds well to treatment, but it can cause fever and facial swelling if it gets worse.
What does a gum abscess look like?
It usually looks like a swollen, red bump on the gum, sometimes with pus. It may hurt when you chew or press on it.
Does salt water help a swollen gum?
A warm saltwater rinse can soothe the area and help clean it. It won’t cure an infection or an abscess.
When is a swollen gum an emergency?
Go to the ER if you have a fever of 100.4°F or higher, facial swelling, trouble swallowing or breathing, confusion or a fast heart rate.
The Bottom Line
Swelling around one back tooth is usually your mouth telling you something is stuck, irritated or infected. Floss gently, rinse with warm salt water and watch it for a day or two. If it isn’t getting better, or you notice a bump, pus, fever or spreading pain, see your dentist. I learned the hard way that mouth infections don’t fix themselves.
Wondering about your morning cup? Here’s when you can drink coffee after wisdom teeth removal.
