Humans go through two whole sets of teeth in our lifetimes — as is the case for most mammals! We are born without teeth. We simply do not need them until a few months after birth because our digestive systems need time to develop enough to process solid food. Babies grow their first set of teeth, called “milk teeth,” a few months after they are born. At about age six, these primary teeth start falling out. This makes room for about 32 permanent teeth that, with proper care and hygiene, we can keep as long as we live.
An average adult has 32 permanent teeth — 16 in the lower jaw and 16 in the upper jaw — by about age 21. The third set of molar teeth located at the back of the oral cavity, AKA wisdom teeth, emerge later in life (though they’re there the whole time).
Human teeth are fascinating in many ways, especially in their development and purpose. Let’s look at the different types of teeth we have in our mouths, the way primary and secondary teeth work, and when teeth start and stop growing in humans.
Different Types of Teeth
Apart from making your smile big and bright, your teeth perform a variety of functions. They help you break down the food you eat and shape your facial structure, allowing you speak and sing.
There are four types of teeth in a human mouth that work together to keep you fed, healthy, and happy. Here’s a breakdown of an adult’s full set of 32 permanent teeth.
Incisors are the front teeth located in the very front of your upper and lower jaws. We have eight: four on the top and four on the bottom. Both rows of incisors have sharp and thin cutting edges that come together to cut food like a pair of scissors.
The canines are sharp and pointy teeth on either side of the incisors. We have four: two canine teeth at the top and two on the bottom. Human canine teeth are slightly pointed and are almost the same length as the other types of teeth — if you are trying to recognize a vampire, it’s the long and sharp canines you should watch out for.
These teeth rip and tear food. They also guide your bite when talking and chewing.
There are eight premolar teeth in our mouths. They have at least two cusps and are bigger than incisors and canine teeth. They also have ridges that help you crush food. Premolars are called “transitional teeth” because they share the characteristics with canine teeth and molar teeth, which break up and crush food.
At the very back of the mouth lie the molars. The term molar derives from the Latin word for “millstone,” which perfectly describes their function. Molars are the largest teeth with broad and jagged surfaces. They help you grind and break down foods with hard textures, making it easier for you to swallow.
Human molars have either four or five cusps. Adults have six molars in each jaw. Four of these molars are called the “first” and “second” or “six-year” and “12-year” molars. Wisdom teeth are the third set of molars that usually appear last. We typically have four “wisdom teeth,” but some people develop fewer ones or none at all.
When Do Teeth Start Growing?
Teething is the process of the first tooth eruption in babies. The exact timing of teething can vary from child to child, but most babies start teething by the time they are 12 months old. Usually, the incisors come first, followed by canines, the first set of molar teeth, and then the set second molar teeth.
The process of eruption for a single tooth often takes about eight to 10 days, which can often be painful for the child. Parents are recommended to provide their babies with chilled teething rings to help reduce the pain and discomfort associated with teething.
By the age of three, children develop a full set of 20 primary teeth. Good oral hygiene habits should start at birth. Proper care for baby teeth will help digestion and speech in children and create a healthy environment for their permanent teeth to grow.
When Do Adult Teeth Come In?
At the age of about five or six, when a child’s jaw and the skull have grown enough to accommodate permanent teeth, their primary teeth slowly start to get loose or “wobbly” and fall out one by one.
This happens as a way to make space for the secondary or adult teeth. Interestingly, on average, girls tend to start losing their teeth sooner than boys. The first teeth that fall off are often the incisors in the lower jaw.
As baby teeth fall out, adult teeth begin growing in their places. The first molars start erupting around the same time. It takes until a person is about 21 years old to fully grow the complete set of 32 teeth.
Depending on the shape and the size of a person’s jaw, their third molars, or “wisdom teeth,” can erupt, become impacted under the gums, or not develop at all.
Wisdom Teeth and How They’re Different
Wisdom teeth are the final set of molars that erupt to complete the full set of permanent teeth. They usually come in around the ages of 17 to 21. But, for some people, they can emerge even later in life, like their early 30s.
The primary purpose of wisdom teeth is to help us grind away coarse food. This is a byproduct of evolution. Our eating habits and even our bodies have changed drastically over time.
As a result, it is common for many people to have jaws that are too small to accommodate their wisdom teeth. In many cases, this means that the teeth are still present, but impacted beneath the gum tissue. However, some people may naturally be missing one or two wisdom teeth entirely. And while it’s much rarer, some people don’t grow any wisdom teeth at all, leaving them with 28 permanent teeth.
It’s perfectly possible for people to have a healthy digestive process without wisdom teeth. In fact, wisdom teeth extraction is often recommended as a preventive measure for those with smaller jaws in order to prevent overcrowding and wisdom tooth headaches.
Oral health is a window into the general health of a person, as problems in the oral cavity can affect the rest of the body. Therefore, regularly practicing good oral hygiene, like daily brushing and flossing, is important to maintain our overall health.