Swollen Gums Around One Tooth: 7 Possible Causes

Swollen gums are a common sign of gum inflammation. While there are many causes, the most frequent is a bacterial infection due to plaque buildup.

This condition usually affects the gums along the gum line. When swelling occurs around just one tooth, it often points to a localized issue, making that spot more prone to bacterial invasion.

In this article, we’ll look at the various reasons your gums might swell around a single tooth, from the most common causes to the rare ones.

1. Gum Inflammation or Gingivitis

Gingivitis is just a fancy term for "inflammation of the gums." It’s the mildest and earliest stage of gum disease. Studies have shown that it can affect up to 90% of people. This might surprise you because gingivitis can be so mild that it’s easy to overlook.

What causes gingivitis? The main culprit is plaque—a thin, sticky, white film that constantly builds up on our teeth and gums. Bacteria use plaque as a shelter to survive and thrive in the mouth.

It only takes a few days without brushing and flossing for plaque to thicken and gum inflammation to set in. The most common signs are red, swollen, and bleeding gums.

Gingivitis usually affects the gums around several teeth. If it appears around just one tooth, it often means that you're missing that spot during brushing and flossing. This is likely to be one of the back teeth, as they are harder to reach and clean properly.

Treat Gingivitis Before It’s Too Late

Think of gingivitis as an early warning sign that it’s time to take action right away.

As we said, it’s the earliest and mildest stage of gum disease. The good news is it’s also completely reversible with some simple improvements to your oral hygiene routine.

If left untreated, gingivitis can progress into a more severe form of gum disease called periodontitis, where the bone and ligaments supporting your teeth start to break down.

To reverse gingivitis:

• Brush your teeth properly for a full 2 minutes, twice a day.


• Make sure to brush every side of your teeth. Missing even a small spot can allow bacteria to build up and cause inflammation.


• Floss once a day, preferably at night before bed, to remove plaque from between your teeth.


• Scrape your tongue daily to reduce the bacteria in your mouth and improve your breath as well.

2. Gingival Abscess Due to Something Stuck in Your Gums

A swollen gum in one area around your teeth could also be a sign of an abscess.

There are several types of gum abscesses, including gingival, periapical, and periodontal abscesses.

A gingival abscess occurs when something gets stuck in the space between your gum and tooth, usually food. This triggers your body to respond with significant inflammation and swelling.

If you’ve recently eaten something hard and crunchy, like potato chips or popcorn, it could be the culprit.

It could also be another object, such as a strand of dental floss or a bristle from your toothbrush.

Common symptoms of a gingival abscess include:

• Isolated swelling that looks like a pimple or nodule near the gum line.
• The affected area is smooth, shiny, and red.
• A clear yellow fluid (pus) is leaking from the gum line.
• Severe pain that makes it difficult to brush, floss, or eat.

A gingival abscess is not the same as gingivitis. An abscess is a more severe form of infection. The pain is more intense, and there’s fluid (pus) leaking from your gums, which isn’t a symptom of gingivitis.

Treating a gingival abscess mainly involves removing the foreign object from your gum.

If you can’t remove it yourself through brushing and flossing, don’t wait—see your dentist for help.

Once the stuck object is removed, the infection can clear, and your gums will heal.

3. You May Have a Tooth Infection

Swollen gums caused by an infected tooth are known as a periapical abscess (or simply, a tooth abscess).

The most common cause is an untreated cavity or tooth decay.

Swelling is likely a tooth abscess if the affected tooth appears decayed or severely damaged.

When a cavity is left untreated, bacteria continue to break down the tooth layers and can reach the nerves.

From there, bacteria may spread into the roots, eventually reaching the surrounding bone and gums. This is when swelling near the infected tooth becomes noticeable, typically around the root tip.

Common symptoms include:

• Intense toothache or gum pain, especially when pressure is applied or when biting.
• Bad breath and a foul taste in your mouth.
• Swollen gums with pus leakage.
• A sensation that the tooth feels longer than usual.
• A feeling of heat in the affected area.

A dental abscess should never be ignored or postponed. It won’t heal on its own and can worsen over time. Left untreated, it can destroy a significant portion of the jawbone, leading to tooth loss.

In the most severe cases, the infection can spread further, posing a serious threat to your overall health.

4. Viral Infection (Oral Herpes)

Aside from bacterial plaque, gingivitis can sometimes result from a viral infection. The most common viral infection in the mouth is oral herpes, caused by the herpes simplex virus type 1 (HSV-1).

Nearly 67% of adults under 50 carry the dormant form of HSV-1. Most of the time, it remains inactive and causes no symptoms.

The virus can occasionally reactivate throughout life, leading to sores commonly known as cold sores. While these sores usually appear on the lower lip, they can also develop anywhere in the mouth, including the gums.

The sores typically appear as fluid-filled blisters that break open, leaving painful ulcers. Mouth sores caused by herpes usually heal on their own within 1–2 weeks. To speed healing and relieve discomfort, your doctor may prescribe topical antivirals or numbing gels.

5. You May Have Injured Your Gums

Gum injuries often occur during tooth brushing or when you chew something hard. It can also happen if you drink something very hot or use a product that’s too harsh or acidic on your mouth.

If you've accidentally hurt your gums, you might notice redness, swelling, and possibly white patches or ulcers.

Gum injuries from trauma usually heal on their own, but it’s important to avoid the cause of the injury to prevent further damage.

6. Hormonal Changes

Hormonal changes can also be a major contributor to gum inflammation and swelling.

Shifts in hormones, such as during pregnancy or puberty, can make your gums more sensitive to plaque and oral bacteria. This heightened sensitivity can result in more severe inflammation and swelling.

The symptoms resemble gingivitis but are more pronounced, with increased bleeding, redness, and swelling.

7. Swollen Gums and Systemic Diseases (Though Rare)

Swollen gums can sometimes signal systemic diseases, although this is less common.

One inflammatory autoimmune condition is lichen planus, which affects up to 2% of the population. The exact cause is unknown, but it’s believed to involve an abnormal immune response that damages healthy cells in the lining of the mouth. On the gums, lichen planus can cause red, painful areas similar to gingivitis, sometimes accompanied by white patches and ulcers.

A rarer autoimmune condition is pemphigus, where the body mistakenly attacks its own cells. This disease can lead to fluid-filled blisters that burst quickly, leaving painful sores, which can appear anywhere in the mouth.

Swollen gums can also be a sign of an allergic reaction, caused by certain foods or ingredients in oral hygiene products like toothpaste. But, allergy-related gum swelling is usually diffuse and rarely limited to a single tooth.