Wisdom teeth can cause a surprisingly wide range of problems, from gum infections and damage to neighboring teeth to cysts, sinus issues, and jaw pain. About half of all adults in the U.S. have at least one wisdom tooth extracted by age 25, and roughly 70% will by age 60. These third molars are the last teeth to come in, typically between ages 17 and 25, and the trouble they cause usually stems from one basic problem: most jaws don’t have enough room for them.
Pericoronitis: The Most Common Problem
The single most frequent reason wisdom teeth get removed is a gum condition called pericoronitis. When a wisdom tooth only partially breaks through the gum, a flap of soft tissue covers part of the tooth. Food and bacteria get trapped underneath that flap, leading to inflammation, swelling, and pain. The area can become so swollen that it’s hard to open your mouth fully.
Pericoronitis can come and go in mild episodes, or it can escalate into a more serious infection with pus, fever, and pain that radiates into the ear or jaw. Because the tissue flap won’t go away on its own as long as the tooth remains partially covered, the condition tends to recur until the tooth is removed or fully erupts.
Damage to the Tooth Next Door
When a wisdom tooth grows in at an angle, it can press directly against the second molar in front of it. That constant pressure can damage the neighboring tooth’s root or enamel, raise the risk of infection in the area, and even push other teeth out of alignment. The second molar is particularly vulnerable because the tight space between the two teeth becomes nearly impossible to clean with a toothbrush or floss.
Over time, bone loss can develop on the back side of the second molar, weakening its foundation and making it more susceptible to both cavities and gum disease. In some cases, the damage to the second molar becomes severe enough that both teeth need to be removed, a situation that’s entirely preventable with earlier intervention.
Tooth Decay and Gum Disease
Even wisdom teeth that erupt fully can cause problems simply because of where they sit. Positioned at the very back of the mouth, they’re difficult to reach with a toothbrush and nearly impossible to floss properly. That makes them magnets for plaque buildup, which leads to cavities and chronic gum inflammation.
The decay doesn’t always stay confined to the wisdom tooth itself. Bacteria that accumulate around a poorly cleaned wisdom tooth can spread to adjacent teeth and gum tissue, creating pockets of infection that deepen over time. Many people don’t realize a wisdom tooth is decaying until the damage is already significant, because the location makes it hard to see or feel early cavities.
Cysts and Tumors
Each wisdom tooth develops inside a small sac within the jawbone. When the tooth becomes impacted (stuck below the gum line), that sac can fill with fluid and form a cyst. A systematic review of multiple studies found that about 5.3% of impacted wisdom teeth are associated with cysts or tumors. The most common type, called a dentigerous cyst, appeared in roughly 2% of cases.
Cysts grow slowly and often produce no symptoms for years, but they can hollow out significant portions of the jawbone, damage the roots of nearby teeth, and, in rare cases, fracture the jaw. Tumors are much less common, occurring in about 0.5% of impacted wisdom teeth. The most frequently reported type is a slow-growing but locally aggressive tumor that requires surgical removal along with a margin of surrounding bone. This is one reason dentists monitor impacted wisdom teeth with periodic X-rays even when they aren’t causing pain.
Sinus Pressure and Infections
Upper wisdom teeth sit just beneath the maxillary sinus, the hollow cavity behind your cheekbones. In some people, the roots of these teeth are so close to the sinus floor that they press against or irritate the sinus lining as they grow. This can create a feeling of pressure, stuffiness, or dull pain in the cheek area that’s easy to mistake for seasonal allergies or a cold.
In more serious situations, an infected upper wisdom tooth can allow bacteria to spread directly into the sinus, causing sinusitis. If the tooth is extracted and the barrier between the socket and the sinus is very thin, a small opening can form between the mouth and sinus cavity. This complication, while uncommon, requires additional treatment to close the connection and prevent chronic sinus problems.
Do Wisdom Teeth Cause Crowding?
This is one of the most debated questions in dentistry. For decades, many oral surgeons and orthodontists assumed that erupting wisdom teeth push forward on the other teeth and crowd the lower front incisors. A 1971 survey found that about 65% of orthodontists and oral surgeons believed this was true, and prophylactic removal to prevent crowding was common practice.
The scientific evidence, however, is mixed. Systematic reviews of the available research have found contradictory results, with some studies supporting the crowding theory and others finding no meaningful effect. The current consensus leans toward wisdom teeth being just one of many factors that can contribute to crowding, alongside jaw growth patterns, tooth size, and age-related changes in the dental arch. Lower incisor crowding happens even in people who never developed wisdom teeth, which suggests it’s not a simple cause-and-effect relationship. Swedish orthodontists, for example, are far less likely than their American counterparts to recommend wisdom tooth removal for this reason, with only 18% believing wisdom teeth cause anterior crowding compared to 36% of American orthodontists.
Nerve Involvement
Lower wisdom teeth sit near a major nerve that runs through the jawbone, supplying sensation to the lower lip, chin, and tongue. When the roots of a wisdom tooth grow close to or wrap around this nerve canal, the tooth can put pressure on the nerve and cause tingling, numbness, or pain in the lip or chin.
Dentists use X-rays to look for specific warning signs that the nerve and tooth roots are in close contact, such as changes in root shape, interruptions in the visible outline of the nerve canal, or the canal being pushed out of its normal path. A study of over 400 wisdom tooth extractions found that when none of these warning signs were present on the X-ray, no nerve exposures occurred during surgery. When signs are present, more advanced imaging helps plan a safer approach to extraction.
Jaw Stiffness and Referred Pain
Impacted or partially erupted wisdom teeth can cause stiffness and difficulty opening the mouth, particularly when inflammation or infection is involved. The swelling from pericoronitis or a developing abscess can spread into the surrounding muscles, making it painful to chew, talk, or fully open the jaw.
Pain from wisdom teeth doesn’t always stay local. It can radiate along the jaw, up toward the ear, or into the temple, mimicking earaches or tension headaches. This referred pain sometimes leads people to seek treatment for the wrong problem before the wisdom tooth is identified as the source. Persistent one-sided jaw pain, especially combined with swelling at the back of the mouth or a bad taste from draining infection, is worth having evaluated with a dental X-ray.