Anatomy and physiology of the teeth

In the mouth, the bone holding the bottom row of teeth is the mandible, and the bone holding the top row of teeth is the maxilla.

The mandible and maxilla - like most bones in the human body - have a core of less dense cancellous bone, wrapped in an outer layer of more dense alveolar bone.

The part of the mandible and maxilla that are in the mouth are covered by the gums. And the teeth rest in bony sockets within the mandible and maxilla and are surrounded by the gums.

Usually, at around six months of age, infants will have their first pair of deciduous teeth, also called milk teeth or baby teeth, erupt through the gums and into the mouth.

New deciduous teeth continue to erupt every one to two months until the baby is around two years old and has a full set of deciduous teeth.

Since the mouth is symmetrically divided down the middle, let’s look at just one side of it.

The teeth that pair up vertically have the same names.

Starting at the front of the mouth, in the center, there are the central incisors and then the lateral incisors. These teeth are shaped like chisels and are good at biting off small bits of food.

Next, are the canines, which got their name from being the same teeth that are extra long and sharp in dogs. They’re also called the cuspids, which comes from the word cusp, meaning point. They’re good for puncturing holes, tearing things, and are an essential part of any vampire costume.

Both incisors and canines typically have one root each.

Then, there are the first molars and the second molars. Molars usually have four to five cusps, and are great for crushing and grinding food. That makes 20 deciduous teeth in total.

As the permanent teeth grow in the bone below the deciduous teeth throughout childhood, the roots of the deciduous teeth begin to get absorbed into the gums. This loosens them and allows them to fall out, making room for the permanent teeth to take their places.

These permanent teeth are also called the adult teeth or succedaneous teeth, which means to succeed or follow after.

Children usually begin to lose teeth starting around age six and the process finishes around age 12.

As the permanent teeth move in, a few more types of teeth begin to show up.

Starting from the center of the mouth again, the permanent teeth include the central and lateral incisors, and then the canines, just like before.

But then, the teeth that replace the deciduous molars are called the first and second premolars or bicuspids. As the name bicuspid suggests, they have two cusps each, and each has one root. Just like the molars, these teeth are great for crushing and grinding food.