An impacted wisdom tooth is one that doesn’t have enough room to fully emerge through the gum line, and the most telling signs are persistent pain at the back of your jaw, swollen or red gums behind your last molar, and difficulty opening your mouth. Some impacted wisdom teeth cause no symptoms at all and are only discovered on a dental X-ray, but when problems develop, the signs tend to be hard to ignore.
Symptoms You Can Feel
The classic symptom is a deep, aching pain at the very back of your jaw, often on one side. This isn’t the brief, mild soreness you might feel when a tooth is erupting normally. Impaction pain tends to linger for days or weeks, and it can radiate into your ear, temple, or the side of your neck. You may also notice that your jaw feels stiff or that it’s harder than usual to open your mouth wide.
Swelling around the jaw is another common sign. It can show up as puffiness along the lower jawline or a general feeling of tightness in the area. Some people notice increased pressure or throbbing when chewing, especially on food that hits the back teeth.
Symptoms You Can See
If you pull your cheek back and look at the gum tissue behind your last molar, you may notice redness, swelling, or a flap of gum tissue partially covering a tooth that’s only partway through. That flap is a hallmark of partial impaction, and it creates a pocket where food and bacteria collect easily.
Other visible or noticeable signs include:
- Tender or bleeding gums when you brush or press on the area behind your last molar
- Bad breath that persists even after brushing and flossing
- An unpleasant taste in your mouth, which can signal pus or drainage from an infection under the gum flap
- Pus or whitish discharge around the partially erupted tooth
Normal Eruption vs. Impaction
All wisdom teeth cause some discomfort as they push through the gums, typically between ages 17 and 25. Normal eruption pain is mild, comes and goes over a few days, and fades once the tooth breaks through. You can usually see the tooth emerging evenly through the gum.
Impaction feels different. The pain doesn’t resolve on its own, and the tooth either stays completely hidden beneath the gum or only pokes through partway at an odd angle. If you notice that one wisdom tooth seems stuck in place while others have come in, or that pain in the area keeps returning every few weeks, impaction is the more likely explanation. The recurring nature of the discomfort is one of the most reliable clues before you ever see a dentist.
Pericoronitis: The Infection Risk
Partially erupted wisdom teeth are especially prone to a gum infection called pericoronitis. The flap of tissue covering the tooth traps food particles and bacteria in a space that’s nearly impossible to clean with a toothbrush or floss. The result is an inflamed, painful infection right at the back of your mouth.
Acute pericoronitis comes on fast. The gum tissue turns red and swollen, and you may see pus draining from around the tooth. It can make swallowing uncomfortable and cause the lymph nodes under your jaw to swell. Chronic pericoronitis is subtler: a persistent bad taste, mild soreness that flares up periodically, and bad breath that won’t go away. Both forms are strong indicators that a wisdom tooth is impacted or only partially erupted.
The Four Types of Impaction
Not all impacted wisdom teeth are stuck the same way. A dental X-ray reveals the angle and depth of the tooth, which falls into one of four categories.
Mesial impaction is the most common type. The tooth is angled forward, pushing toward the molar in front of it. It may be partially visible above the gum line. Vertical impaction means the tooth is pointed in the right direction but remains trapped below the gum, never breaking through. Horizontal impaction is one of the more problematic types: the tooth lies completely on its side beneath the gum and pushes directly into the roots of the neighboring molar. Distal impaction is the rarest, with the tooth angled toward the back of the mouth, away from the other teeth.
You can’t determine the type of impaction on your own. But knowing these categories helps you understand your dentist’s explanation if an X-ray confirms the problem.
How Dentists Confirm Impaction
A visual exam alone can suggest impaction, but the definitive answer comes from a dental X-ray. Your dentist will take a panoramic image that shows all of your teeth, the jawbone, and the position of any wisdom teeth still below the gum. This image reveals exactly how the tooth is angled, how deep it sits, and whether it’s pressing into the roots of your second molar or affecting the surrounding bone.
If you suspect impaction based on your symptoms, an X-ray is the only way to know for certain. Many impacted teeth sit entirely below the gum with no visible sign in the mouth, and some partially erupted teeth that look fine on the surface are actually angled into neighboring teeth underneath.
What Happens If You Ignore It
An impacted wisdom tooth that isn’t causing symptoms right now can still cause damage over time. Because the tooth is pressing against the second molar, it can gradually damage that tooth’s root or erode the bone supporting it. The hard-to-clean gap between a partially erupted wisdom tooth and the molar next to it is also a common site for cavities on both teeth.
Repeated bouts of pericoronitis can lead to deeper infections that spread into the jaw or the soft tissues of the throat. Fluid-filled cysts can also develop around an impacted tooth, though this is less common. The longer an impacted tooth stays in place, the more complex removal tends to be, since the roots continue to develop and the bone around them becomes denser with age.