The Functions of Molar and Wisdom Teeth

Referred to as molars or molar teeth, these are the flat teeth located at the back of the mouth. They can vary in size and shape but are the largest teeth in the mouth. Molars are rounded and used for grinding food into easily swallowed pieces. The smaller and sharper front teeth are used for biting and tearing food. Molars are designed to sustain great amounts of force from chewing, grinding, and clenching, and each molar is anchored to the jaw bone with two to four roots.

The average adult has twelve molars, with six in the upper jaw (identified by your dentist as "maxillary" for their location in the upper jaw) and six in the lower jaw (identified as "mandibular" by the dentist for their location in the lower jaw). Each side of the upper and lower jaw has three molars.

There are three types of molars. These come in after a child loses their baby teeth:

• First molars, also called the six-year molars because they are the first of the three to erupt around age six.
• Second molars, also called the twelve-year molars because they erupt around age 12.
• Third molars, or wisdom teeth, which appear between the ages of 17 and 21.

Anatomically, molars are designed to sustain great amounts of force from chewing, grinding and clenching, by having a large crown and two to four roots firmly implanted in the jaw bone.

The third molars, or wisdom teeth, are vestiges from our evolutionary past when the human mouth was larger and more accommodating to additional teeth. These additional teeth were useful in chewing especially course foods, such as roots, nuts, leaves, and tough meats. This type of diet was tough on the teeth—especially without the helpful maintenance tools we enjoy today like toothbrushes, paste, and floss—so our ancestor's teeth were subject to significant wear and loss due to tooth decay.

Even with the current popularity of "Paleo diets," modern humans do not consume foods that require these extra teeth. Our foods are generally far softer, and with cooking and utensils, the day of the useful wisdom tooth has passed. Evolution, however, has not caught up with us yet, and so we still get those extra teeth late in our youth.

Though it hasn't dumped our wisdom teeth yet, evolution has, unfortunately, made some adjustments to the size of our jawbones throughout our history. The jaws of modern humans are smaller than our ancestors. This presents a range of problems when those vestigial wisdom teeth try to squeeze in. 

When wisdom teeth form, they can become blocked by our other teeth, and they're referred to as being "impacted." If a wisdom tooth partially erupts, this can create a hard-to-reach haven for bacteria that can lead to serious infections of the gums and surrounding tissue. Wisdom teeth may also never erupt. This carries with it problems as well, including potential development of cysts or tumors that can do considerable damage to the jawbone and teeth if left unaddressed.

These problems are the reason many people need to have their wisdom teeth removed. It is recommended that this surgery is performed during young adulthood when any complications are least likely and minimal.

Some people may have no immediate need to have their wisdom teeth removed, because they come in without issues: One study puts the number at about 15 percent of the population. Even in these cases, it may be recommended that the wisdom teeth be removed to avoid problems that might develop later in life when surgery has more potential for complications and longer healing times.