Sometime between ages 17 and 21, most adults will develop their third set of molars. These molars are more commonly called wisdom teeth.

Teeth are categorized by their placement and function. The sharper teeth can tear food into smaller pieces and the flatter teeth grind food down. Wisdom teeth are the flatter kind of teeth, called molars. Molars are all the way in the back of your mouth. Adults get three sets of molars on top and bottom, and on both sides of the mouth.

From infancy through early adolescence, humans develop their first set of teeth, lose them, and get a whole new set again. There’s a brief pause and then again, in early adulthood, the final set of teeth emerge.

They’re called wisdom teeth because they’re the last teeth to emerge. You’re presumably “wiser” when these teeth come in.

How frequently do people get wisdom teeth?

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 grow in. The first set of molars usually becomes visible at age 6, the second set around 12, and the final set (wisdom teeth) sometime before age 21.

Once essential for an early human diet of roots, leaves, meat, and nuts, wisdom teeth are no longer totally necessary. Today, humans cook food to soften it, and we can cut and crush it with utensils.

Anthropologists believe humans have evolved beyond needing wisdom teeth, so some people may never get any. Wisdom teeth may go the way of the appendix and become completely unnecessary. It wouldn’t be surprising to some researchers if someday nobody had wisdom teeth anymore.

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

However, 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.

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

Why are wisdom teeth removed?

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.

Our diet and dental needs have also changed drastically. Smaller jaws mean there isn’t always enough room in the mouth for all the teeth we’re supposed to have. There are four wisdom teeth in total, two on top and two on the bottom. People can have any number of wisdom teeth from none to all four.

Most jaws are done growing by the time a person is 18 years old, but most wisdom teeth emerge when a person is around 19.5 years old. Most problems caused by wisdom teeth are due to the fact that they just don’t fit.

Problems associated with wisdom teeth include:

The American Dental Association indicates that removal will be necessary if any of the above changes are apparent.

Its 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.

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.

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.