Teeth are categorized by their placement and function. Sharper teeth near the front of your mouth tear food into smaller pieces, while flatter teeth at the back of your mouth grind the food down. These flatter teeth are called molars. Adults have three sets of molars, each set consisting of four teeth on the top, bottom, and both sides of the mouth.

From infancy through early adolescence, humans develop their first set of “baby” teeth, lose them, and then get a whole new set again that they’ll keep for life. But only two sets of molars (8 teeth), arrive during the emergence of those adult teeth. Sometime between the ages of 17 and 21, most adults will develop their third set of molars, which sit the farthest back. These molars are more commonly called wisdom teeth because they show up last, when you’re “older and wiser.”

The rough diets of our human ancestors (think much less tender meat than what we’re able to prepare today), may have necessitated this third set of molars.

All of the teeth a person will ever have are present at birth, higher up in the skull structure. First, a set of 20 baby teeth erupts and falls out. Then 32 permanent teeth move in. The first set of molars usually becomes visible at age 6, the second set around age 12, and the final set (wisdom teeth) sometime before age 21.

Because of the ease of our modern diets, anthropologists believe humans have gradually evolved beyond needing wisdom teeth, so some people may never get any. Wisdom teeth will likely go the way of the appendix and become completely unnecessary. Eventually, they may disappear altogether

Still, most adults today develop their wisdom teeth. One study found that at least 53 percent of people aged 25 and older had had at least one wisdom tooth come in. Men were more likely to have them than women.

Just because you don’t see all of your wisdom teeth doesn’t mean they aren’t there. Sometimes wisdom teeth don’t ever erupt and won’t ever become visible. An X-ray can confirm if you have wisdom teeth under your gums.

Humans and our jaws have gotten smaller over time. There are probably a few reasons for this evolutionary progress. Some scientists believe that as the human brain grew bigger over time, the jaw got smaller to accommodate for space. Most problems caused by wisdom teeth are due to the fact that they just don’t fit.

Whether visible or not, wisdom teeth can cause oral health problems. Wisdom teeth that haven’t erupted through the gums are known as impacted teeth. Sometimes this causes even more problems than visible wisdom teeth do.

Problems associated with wisdom teeth include:

Wisdom teeth are more susceptible to infection than most other teeth for a few reasons. Their position in the very back of the mouth can make it difficult to floss next to them correctly, allowing bacteria to multiply.

Because they emerge into a mouth already full of teeth, wisdom teeth can also remain partially impacted, creating more hard-to-reach nooks and crannies. In some cases, soft tissue can grow over a partially impacted wisdom tooth, causing an infection known as pericoronitis.

Symptoms of a wisdom tooth infection can include the following:

  • pain or sensitivity
  • tender or swollen gums
  • red or bleeding gums
  • white fluid or oozing around teeth
  • bad breath
  • bad taste in your mouth
  • jaw pain
  • jaw swelling
  • stiff jaw
  • difficulty breathing, opening your mouth, or speaking

If you experience pain around your back molars, make an appointment with your dentist.

A wisdom tooth infection can be treated in multiple ways, depending on the severity and the position of the tooth. Your dentist will first prescribe antibiotics to clear the infection up. Once the area is no longer infected, dental work or surgery is the best way to prevent reinfection.

Your dentist may decide to repair the tooth by filling in a cavity or crevices around the eruption site to minimize the number of spaces bacteria can build up in.

In some cases, surgery, including partial or full removal of the tooth, is the best way to keep the area clean and prevent further discomfort.

Your dentist can help walk you through all the options for your own mouth.

Wisdom teeth are often removed even in the absence of infections. Because they may crowd your mouth as they come in, potentially damaging or shifting other teeth, your dentist may recommend they be removed once they begin emerging, as a preventative measure against future pain.

Sometimes dentists will recommend wisdom tooth removal before any orthodontic work, like braces, to ensure that these teeth don’t erupt later and undo all the hard work of shaping your jaw and teeth.

It’s recommended that teenagers be evaluated for wisdom teeth removal surgery. People who get their wisdom teeth removed at a younger age tend to heal better from surgery, before the roots and bone have fully formed. This can help avoid any potential problems before they start.

There are always risks associated with surgery so be sure to ask a lot of questions when you’re deciding whether or not to have these teeth removed. If you decide not to have your wisdom teeth removed, they need to be monitored closely by your dentist. Wisdom teeth tend to become more problematic over time.

Either a professional dentist or oral and maxillofacial surgeon can remove your wisdom teeth. They’ll give you clear instructions on how to prepare for surgery and what to do during recovery.

Your mouth is more vulnerable to infection after surgery, so it’s important that you follow your dentist’s instructions for keeping your wounds clean. This will likely include salt water rinses, avoiding smoking, and eating foods without small pieces like seeds that can get stuck in your healing gums.

Recovering from wisdom tooth surgery generally takes a few days, but some pain can last for up to a week. Ask your dentist about which pain medications are safe to use.

Recovering from having your wisdom teeth removed can be uncomfortable, but for many people it’s a great way to avoid more dental procedures in the long run.