The most common reason gum tissue grows over a back tooth is a partially erupted wisdom tooth. When a wisdom tooth doesn’t fully break through the surface, the gum forms a flap (called an operculum) that drapes over part of the tooth’s crown. Food, bacteria, and debris get trapped underneath that flap, often leading to swelling, pain, and infection. This condition is called pericoronitis, and it’s one of the most frequent problems dentists see with wisdom teeth.
That said, a partially erupting wisdom tooth isn’t the only explanation. Certain medications, chronic irritation, and reactive tissue growths can also cause gum tissue to creep over a back molar.
Pericoronitis: The Most Likely Cause
Wisdom teeth typically come in between ages 17 and 25, and they often don’t have enough room to emerge fully. A tooth can get stuck at an angle, tilting toward the neighboring molar, angling toward the back of the mouth, or even lying sideways within the jawbone. Any of these positions can leave the tooth partially trapped beneath the gum, creating a pocket where the tissue overlaps the tooth surface.
That pocket is almost impossible to keep clean with normal brushing. Bacteria thrive in the warm, moist space under the gum flap, and the result is inflammation that makes the tissue swell even more, covering more of the tooth. You might notice redness, tenderness when chewing, a bad taste in your mouth, or swelling along the back of your jaw. In mild cases the discomfort comes and goes. In more severe cases the infection can spread, causing throbbing pain that radiates into your ear or neck, fever, swollen lymph nodes under your jaw, or difficulty opening your mouth fully. Trouble swallowing or breathing is a sign the infection has spread to deeper tissue and needs urgent attention.
Medications That Trigger Gum Overgrowth
If the tooth in question isn’t a wisdom tooth, or if you’re noticing gum tissue bulging around several back teeth, medications could be the cause. Three classes of drugs are most frequently linked to gum overgrowth:
- Certain blood pressure medications (calcium channel blockers like nifedipine and amlodipine)
- Anti-seizure medications (particularly phenytoin)
- Immunosuppressants (such as cyclosporine, often prescribed after organ transplants)
These drugs interfere with the way gum cells process folate, a B vitamin needed to break down and recycle collagen. Without enough active folate inside gum cells, old collagen doesn’t get cleared away. New collagen keeps piling on top of it, and the tissue gradually enlarges. The severity is directly proportional to how much plaque builds up around the teeth, so people on these medications who have even moderate plaque tend to see worse overgrowth than those with excellent oral hygiene. If you take any of these drugs and notice your gums swelling over your back teeth, your dentist and prescribing doctor can discuss whether switching medications or adjusting your dose is an option.
Reactive Growths From Chronic Irritation
Sometimes the gum tissue over a back tooth forms a firm, localized lump rather than a broad flap. This could be a fibrous epulis, a benign growth that develops in response to ongoing irritation from plaque buildup, tartar, a rough filling edge, or a poorly fitting crown or partial denture. Fibrous epulis is the most common type of these reactive growths, accounting for roughly 47 to 61 percent of cases in large studies. It’s more common in women, possibly because hormonal fluctuations encourage gum tissue to grow.
These growths are not cancerous. They’re your gum’s overreaction to something rubbing or irritating it repeatedly. In some younger lesions, simply removing the source of irritation (cleaning off the tartar, smoothing a rough restoration) can cause the tissue to shrink on its own. Larger or more established growths typically need to be surgically removed. Recurrence is common if the underlying irritant isn’t eliminated.
What You Can Do at Home
If you’re dealing with a gum flap over a partially erupted wisdom tooth, keeping the area as clean as possible is the single most important thing you can do before your dental appointment. Gently rinse the area with warm salt water several times a day, directing the rinse toward the back of your mouth to flush debris from under the flap. A curved-tip irrigating syringe (available at most pharmacies) can help you direct water under the gum flap more precisely than swishing alone.
Avoid chewing on that side if it’s painful. Stick to softer foods that won’t press sharp edges into the swollen tissue. Over-the-counter pain relievers can help manage discomfort in the short term. What won’t help is ignoring it. Pericoronitis tends to flare repeatedly once it starts, and each episode risks a deeper infection.
How Dentists Treat Gum Overgrowth
Treatment depends entirely on the cause. For pericoronitis around a wisdom tooth, the dentist first addresses any active infection, then decides whether the tooth can be saved or needs to come out. If the tooth is positioned well and has enough room to fully erupt, a minor procedure called an operculectomy removes just the overlapping gum flap. This can be done with a scalpel or a dental laser. Laser removal tends to cause less bleeding and less post-procedure discomfort, though both approaches produce equivalent long-term results. Scalpel removal is less expensive but typically requires a protective dressing over the site for 7 to 10 days.
If the wisdom tooth is impacted at a problematic angle, extraction is usually the better long-term solution. Removing the flap alone won’t prevent future problems if the tooth will never fully emerge.
For drug-induced gum overgrowth, the first step is working with your doctor to see if an alternative medication is available. Improving oral hygiene and getting a professional cleaning can reduce the severity significantly, since plaque is a direct contributor to how much the tissue enlarges. If the overgrowth is severe, a dentist can surgically reshape the gum tissue, but it will likely grow back if you remain on the same medication without excellent plaque control.
Fibrous epulis and similar reactive growths are typically removed with a simple excision. Recovery after any of these gum procedures follows a similar pattern: the first few days involve tenderness and some swelling, with soft foods recommended. The gum tissue heals through what’s called secondary intention, meaning new tissue gradually fills in the area from the edges inward. General health, how closely you follow post-procedure care instructions, and the complexity of the procedure all influence how quickly you heal.
Signs That Need Prompt Attention
Most gum flaps over back teeth are more annoying than dangerous, but certain symptoms signal that the situation has progressed beyond a simple gum flap. A severe, constant, throbbing ache that radiates into your jawbone, neck, or ear suggests the infection may have spread beyond the gum tissue. Fever, visible facial swelling, swollen lymph nodes under your jaw, or a sudden rush of foul-tasting fluid in your mouth (which can happen if an abscess ruptures) all point to a more serious infection. Difficulty opening your mouth, known as trismus, or trouble swallowing means the infection is involving deeper tissue planes and warrants same-day evaluation.