The Functions of Molars and Wisdom Teeth

Molars are the tough workhorses of human teeth

Table of Contents
View All
Table of Contents

Molars are rounded, flat teeth in the back of the mouth. They include your wisdom teeth.

Also called molar teeth, molars can vary in size and shape but are the largest teeth in the mouth. Their role is to grind food into pieces that are easy to swallow, while the smaller, sharper front teeth are used for biting and tearing food.

This article looks at the types of molars you have, why you have wisdom teeth, and problems that can develop in them.

Close up of x ray jaws scan examined by dentist
Zinkevych / Getty Images

Types of Molars

The average adult has twelve molars, three on each side of both your upper and lower jaws. Each of the three molars is a different type:

  • First molars, also called six-year molars because they come in around age six
  • Second molars, also called twelve-year molars because they erupt around age 12
  • Third molars, also called wisdom teeth, which appear between the ages of 17 and 21

Molars are designed to sustain great amounts of force from chewing, grinding, and clenching. That's thanks to their large surface area and two to four roots that are firmly implanted in the jaw bone.

Why Do We Have Wisdom Teeth?

The third molars, or wisdom teeth, are vestiges from our evolutionary past when the human mouth was larger and could accommodate more teeth. They were useful in chewing especially coarse 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, such as toothbrushes, toothpaste, and dental floss. So our ancestor's teeth were subject to significant wear and loss due to tooth decay.

Modern humans don't eat foods that require these extra teeth. However, evolution hasn't yet caught up to this change, so people still get those extra teeth around the time they reach adulthood.

Not Everyone Has Them

About 37% of people never develop wisdom teeth or don't have all four. Some experts believe this is due to evolution.

The Problem of Wisdom Teeth

Wisdom teeth have become a problem because evolution has shrunk the human jawbone. This presents a range of problems when those vestigial wisdom teeth try to squeeze in.

  • As wisdom teeth form, they can become blocked by other teeth so they can't come in properly. This is referred to as being "impacted."
  • If a wisdom tooth does come in, it can crowd the mouth and create hard-to-clean places where bacteria can thrive, leading to serious infections of the gums and surrounding tissue.
  • Wisdom teeth may also never come in. This can lead to cysts or tumors that can do considerable damage to the jawbone (mandible) and teeth if they're not taken out.

These problems are among the reasons many people need to have their wisdom teeth removed. This surgery is generally recommended for young adults, which is often early enough to prevent or minimize complications.

In some people, wisdom teeth come in without any problems. One study suggests that's the case for about 15% of the population.

Even in these cases, the wisdom teeth may need to be removed to avoid problems that might develop later in life, when surgery has longer healing times and more potential for complications.


Molars are the big flat teeth in the back of your mouth. They're designed to crush and grind food and can withstand considerable force.

The three types are six-year molars, twelve-year molars, and wisdom teeth. The modern human diet no longer requires wisdom teeth, so they're called vestigial, meaning they're left over from an earlier time.

The human jaw has shrunk through evolution, which means there's often not enough room for wisdom teeth to come in. That can lead to various problems and most people have their wisdom teeth removed at some point. The surgery is safer and easier to recover from when you're young.

Frequently Asked Questions

  • What causes pain in the molars?

    Some causes of molar pain include:

    Contact your dentist if the pain is severe or lasts more than one or two days. Make an appointment right away if you also have swelling, fever, earache, or pain when opening your mouth wide.

  • When do baby molars come in?

    Your baby's first molars will probably begin to come in between 13 and 19 months old. The last set of baby molars may finish coming in around 25 to 33 months old. These later fall out to make way for adult molars.

  • When do kids lose their molars?

    It varies. On average, kids tend to lose their baby molars when they're between 9 and 12 years old.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Cleveland Clinic. Teeth eruption timetable.

  2. Ghoncheh Z, Zade BM, Kharazifard MJ. Root morphology of the maxillary first and second molars in an Iranian population using cone beam computed tomographyJ Dent (Tehran). 2017;14(3):115-122.

  3. Jung YH, Cho BH. Prevalence of missing and impacted third molars in adults aged 25 years and above. Imaging Sci Dent. 2013;43(4):219–225. doi:10.5624/isd.2013.43.4.219

  4. Rakhshan V. Congenitally missing teeth (Hypodontia): A review of the literature concerning the etiology, prevalence, risk factors, patterns and treatmentDent Res J (Isfahan). 2015;12(1):1-13. doi:10.4103/1735-3327.150286

  5. Jung YH, Cho BH. Prevalence of missing and impacted third molars in adults aged 25 years and aboveImaging Sci Dent. 2013;43(4):219–225. doi:10.5624/isd.2013.43.4.219

  6. Von Cramon-Taubadel N. Global human mandibular variation reflects differences in agricultural and hunter-gatherer subsistence strategies. Proc Natl Acad Sci USA. 2011;108(49):19546-51. doi:10.1073/pnas.1113050108

  7. Fernandes MJ, Ogden GR, Pitts NB, Ogston SA, Ruta DA. Actuarial life-table analysis of lower impacted wisdom teeth in general dental practice. Community Dent Oral Epidemiol. 2010;38(1):58-67. doi:10.1111/j.1600-0528.2009.00501.x

  8. Cleveland Clinic. Toothache.

  9. American Dental Association. Eruption charts.

By Shawn Watson
Shawn Watson is an orthodontic dental assistant and writer with over 10 years of experience working in the field of dentistry.