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Tooth Truth: Everything to Know About Your Molars

Most people have two sets of teeth during their life: a set of primary or “baby” teeth and then the permanent or “adult” teeth. And making up these sets are four different types of teeth:


  • Incisors
  • Canines
  • Premolars
  • And molars


Each of these types of teeth has a specific purpose, and they have each evolved over time to change with our diets and speech. Just think of how different the modern diet is compared to that of our ancestors in the middle ages, or even before that in the era of cavemen.

Tooth Truth: Everything to Know About Your Molars


Teeth reveal remarkable details about the mouths they’re in, whether our own or those of our ancestors. Fossil teeth are tiny time capsules that provide insights into human evolution, including our diverse diets, extended childhoods and other unique features of our species.


Our mouth has evolved to best suit our needs today, and that is what make the evolutions of humans fascinating. The molars in the mouth have a storied history. Keep reading to learn more about the evolution of molars in the mouth and their unique purpose in life!


Molar use


Molars are your widest and flattest teeth that are found in the back of the mouth. There are three types of molars, aptly named your first molars, second molars and third molars.


While each person’s molars can vary in shape and size, molars are the largest teeth in the mouth. Molars are also the strongest teeth in the mouth. These teeth can exert 70 pounds per square inch, a force that tapers off as you move toward the front of the jaw. This is equivalent to approximately 171 pounds of pressure! And with this force, molars grind down tough food through pressure and force. Unlike sharper teeth like the canines (that can rip meat or other fibrous foods), molars take the longer approach in grinding down food through the chewing process. It is estimated that 90% of chewing takes place with the first molars.


Children’s mouths


While most children have 20 primary teeth—10 in each of the upper and lower jaws—these teeth eventually are replaced by 32 permanent teeth, 16 in each jaw. The first permanent molars usually erupt between ages 6 and 7.


Since these molars in humans erupt around this age—roughly when a child is in kindergarten—they are often called the “six-year molars.” They are among the “extra” permanent teeth in that they don’t replace an existing primary tooth. These important teeth sometimes are mistaken for primary teeth. However, they are permanent and must be cared for properly if they are to last throughout the child’s lifetime. The six-year molars also help determine the shape of the lower face and affect the position and health of other permanent teeth.


By age 13, children have eight molars. These are typically the last teeth to erupt before the “third molars” or “wisdom teeth” appear between the ages of 17 and 21.


Wisdom teeth


Commonly referred to as wisdom teeth due to the age in which they appear (when we’re oh-so-wise), the third molars are the last four teeth adults sprout. These teeth were essential to our prehistoric ancestors, who needed the extra set of molars to chew tough meet and fibrous vegetables. In addition, having an extra set of teeth helps offset any losses of other teeth, which was commonplace before hygiene awareness or medical services.


However, as humans evolved and we left the hunter and gatherer lifestyle, our jaws also changed. Thanks to softer foods, we no longer needed an extra set of molars to help break down what we eat. And with a smaller jaw, 32 teeth could no longer fit properly, and complications would occur (like teeth that wouldn’t fully erupt and would become impacted).


These changes in our jaw and diet have led to more than 5 million people a year having their wisdom teeth removed. Dentists and oral surgeons don’t recommend removal “simply so we have something to do.” Instead, the problem with wisdom teeth is that, through their evolution, there is no longer room for them in the mouth—and that results in poor root quality and oddly-shaped or angled teeth. Even if you do have the space in your mouth, there is a higher likelihood that your wisdom teeth could become infected or lead to the development of other periodontal diseases since they are so far back and much harder to clean. Many times, pulling wisdom teeth is a preventative measure that is done to protect the long-term health of your mouth.


Special protections


In addition to a good oral health routine that includes brushing and flossing, sealants are a special precaution that can be taken to add an extra layer of protection for your molars. Sealants provide a protective cover for the teeth that are most susceptible to cavities (due to their deep grooves).


The procedure to apply the sealant is both quick and painless. An acidic gel is placed on your dry tooth to “rough up” the surface for better application of the sealant itself. Once the gel dries and excess is washed off, the sealant itself is applied to the tooth. Modern sealants are typically resin based of glass ionomer based. A UV light is used to harden the sealant to the tooth.


Once the sealant is applied, it acts as a barrier against food particles infiltrating the deep grooves of your teeth. Studies have shown sealants reduce the risk of decay by nearly 80% in molars. The Centers for Disease Control released a report touting the benefits of sealants and concluded that “school-age children without sealants have almost three times more cavities than children with sealants.” While as of 2016 only 43% of children has sealants, that number continues to grow as more parents become aware of the benefits for their child. For the hard-to-reach teeth in the back, sealants are a good option to ensure protection.

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