Early humans had broader, more powerful jaws in order to chew through tough plant materials and raw foods. A third set of molars, what we call wisdom teeth, helped them break down their foods for digestion. Over time, jaws shrank as humans learned ways to make foods easier to chew with food preparation and utensils. Modern jaws no longer have space for wisdom teeth. So when they grow in, they can cause an array of problems.
Wisdom teeth usually emerge between ages 17 and 25. Removing wisdom teeth is not always necessary—only when they cause pain, get infected, or place pressure on nearby teeth. Many people have their wisdom teeth removed to prevent these problems down the line. Others choose to keep their wisdom teeth if they are healthy, properly aligned, and not causing issues.
Why Did Humans Need Wisdom Teeth?
Our earliest ancestors survived on a diet of raw meat, nuts, roots, berries, and leaves. Chewing these tough, coarse, and fibrous foods required intense chewing power. As such, having broader jaws and three sets of molars, including wisdom teeth, was vital for our ancestors to be able to survive.
The larger jaws of our ancestors easily accommodated these third molars. The wisdom teeth erupted in their mouths normally, without the kinds of complications humans have with them today.
Why We Don't Need Wisdom Teeth Today
As modern humans took shape, our overall structure changed. Over time, the jawbone became smaller and all 32 of the teeth we once had could no longer fit properly.
In addition to these structural changes, humans changed what they eat and how they prepare it. Rather than eating tough foods that require greater chewing power, humans learned to cut, dice, chop, boil, steam, and bake foods.
Jawlines have adapted to changing eating habits by becoming smaller and less broad. Wisdom teeth, however, have outlived their purpose. Modern jaws no longer have room to accommodate them, so they typically need to be extracted to prevent pain, infection, and other complications.
What Age Do Wisdom Teeth Grow In?
Most wisdom teeth erupt (appear) around age 20. Genetics, facial development, jaw size, and tooth size can all influence when wisdom teeth grow in.
Can Wisdom Teeth Cause Problems?
Not everyone with wisdom teeth will experience problems. Many people have wisdom teeth that erupt and function without issues, just like the rest of their teeth.
With that being said, as many as 72% of people with wisdom teeth have at least one impacted third molar. Impaction happens when wisdom teeth do not have enough space to emerge through the gums. As a result, the wisdom teeth can get partially or entirely trapped beneath the gum line.
Wisdom teeth impaction can be quite painful. Most people with impacted wisdom teeth experience swelling in their gums. In some cases, a pocket (abscess) between the gum and impacted tooth can form. An infection called pericoronitis develops when bacteria accumulates there.
Pericoronitis often develops after an upper respiratory infection. It can lead to:
- Increased pain and swelling
- Difficulty opening the mouth
- Bad breath
- Pus
- Facial swelling
Left untreated, pericoronitis can lead to a life-threatening condition called sepsis, in which the body has an extreme and widespread inflammatory response to infection. Sepsis requires immediate medical attention.
Wisdom teeth may also cause:
- Root damage: Wisdom teeth, and especially impacted wisdom teeth, can damage the roots of the second molars. Sometimes, the pressure from the wisdom tooth can cause the second molar's roots to weaken or reabsorb into the gums and compromise the molar's stability.
- Tooth damage: Impacted wisdom teeth in particular can place excessive pressure on the surrounding teeth. This pressure can ultimately damage the function and stability of the neighboring tooth.
- Cysts and tumors: Although uncommon, impacted wisdom teeth can lead to the formation of a fluid-filled sac, called a cyst, around the tooth. Benign (non-cancerous) tumors, called odontogenic tumors, can also develop. Left untreated, these lesions can continue to grow and damage the surrounding teeth and bone.
- General pain and discomfort: Wisdom teeth, whether impacted or not, can be generally painful due to the pressure they place on the gums as well as nearby teeth, bones, and roots.
- Hygienic issues: Wisdom teeth are so far back in the mouth that proper care to keep them healthy can be difficult. As such, wisdom teeth can easily develop cavities (caries).
- Gum disease: Pericoronitis, difficulty cleaning the wisdom teeth, impaction, and the resulting inflammation can eventually cause the gums to get inflamed and infected. These issues can lead to or contribute to gum disease.
- Temporomandibular joint disorders (TMD): Impacted wisdom teeth can cause shifts in the position of the jaw. These shifts can strain the temporomandibular joint and supporting muscles, and may lead to TMJ disorders, which can cause jaw stiffness, face pain, difficulty opening and closing the mouth, bite changes, and more.
Even if the wisdom teeth are not causing a problem in terms of spacing, wisdom teeth may be extracted (removed) to prevent future issues.
What Percent of People Develop Wisdom Teeth?
According to a study published in Dentist Research Journal, as many as 35% of people are born with congenitally missing wisdom teeth, or wisdom teeth that never formed in the first place.
Is There Any Reason to Keep Wisdom Teeth?
For the vast majority of people, wisdom teeth offer limited to no benefits, and it's not important to keep them. There are a few instances in which wisdom teeth can be beneficial, though.
Healthy, properly aligned wisdom teeth can help with chewing, just like any other teeth. For some people, maintaining them can provide support for adjacent teeth and prevent them from shifting.
Mature wisdom teeth can also be transplanted, or used to replace, molars that have been lost or damaged. Third molar transplantation can restore the aesthetic and function of first or second molars that cannot otherwise be restored.
Your dentist may also recommend keeping your wisdom teeth or postponing their removal if you:
- Are pregnant, in which case elective surgeries, such as wisdom teeth removal, are typically postponed until after the baby is born
- Have an active infection around your wisdom teeth, in which case your dentist will want to address the infection first with antibiotics before proceeding with removal surgery
- Are immunocompromised, as your risk of infections and surgical complications is higher
- Are under chemotherapy or radiation therapy, as the drugs involved in these therapies increase your risk of a rare but serious condition called medication-related osteonecrosis, in which the jawbone loses its blood supply and starts to die
Ultimately, if your wisdom teeth are healthy, properly aligned, and not causing you any problems, you may choose to keep them. This decision should be made in close collaboration with your dentist and other healthcare providers involved in your care.
Summary
Early humans required broad jaws and an extra set of molars, or wisdom teeth, to chew through tough plant materials and raw meat. As humans evolved, their jaws shrank, but wisdom teeth outlived their purpose. Modern jaws do not have enough space for wisdom teeth, so they often grow in misaligned or trapped under the gums (impacted). Impacted teeth run a risk of infection, which can lead to serious complications, like sepsis and gum disease, if left untreated.
Not all wisdom teeth need to be removed, though. If they are healthy, properly aligned, and functioning well, you don't need to remove them. Your dentist may determine that wisdom teeth removal surgery is not necessary for you now, or that the risk of surgery outweighs the benefits.