Teeth do have nerves because if they didn't they wouldn't be able to feel any sensations like hot or cold. The tooth nerves are actually a part of the cranial nerve network which stem from your brain.
Evidence of this would be dead teeth or ones that have been root canal treated. That is when the nerve dies or has been forcibly removed with a procedure.
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Are there nerves in teeth?
Yes there are nerves in the teeth and they're located within the tooth pulp, which is at the center of the tooth. It is protected and insulated from the oral environment by the dentin and enamel layers.
The nerves within the pulp extend further down into the canals and exit out of the tooth via the tip of the roots. From the root tip they connect with one of the branches of the fifth cranial nerve known as the trigeminal nerve.
Extensions of the trigeminal nerve
The nerves of your teeth are technically just nerve endings from one of the major branches of the trigeminal nerve. The trigeminal nerve is also known as cranial nerve five or CN V. Therefore you can think of the tooth nerves as an extension of the trigeminal nerve.
The diagram above shows the fifth cranial nerve (trigeminal) and all of the structures that it innervates. It consists of three major branches often denoted by V1, V2, and V3.
Three branches of cranial nerve V:
V1 (opthalmic nerve) - innervates the orbital structures.
V2 (maxillary nerve) - innervates the upper teeth.
V3 (mandibular nerve) - innervates the lower teeth.
The schema above demonstrates how V2 controls the teeth on the upper jaw while V3 controls the teeth on the lower jaw. Basically, the nerves in the pulp of the tooth exit out through the tip of the root and join with their respective branches of the trigeminal. From there they merge and relay information to the brain.
Everyday proof of teeth having nerves
The fact that teeth can feel sensations such as hot and cold are due to having nerves and also why we consider them alive. For instance, if you eat something too hot or too cold, your teeth will immediately react to it. That is to warn you to be careful but it is also an indication that your teeth are vital or alive.
On the other hand you can think of living organisms that have died. Dead beings are not bothered by extremely hot or cold temperatures. For example, people will feel cold if you put them in the arctic but a dead body will not be the least bit bothered by the cold there. The same can be said for your teeth.
Dead teeth
Your teeth can die from infections or after a root canal. The latter is when your dentist removes the nerve from your tooth and the end result is a tooth that can no longer feel any sensitivity. For that reason, teeth are considered dead after a root canal.
Essentially after undergoing a root canal treatment, you've officially a dead tooth. That is direct evidence that your dentition has nerves since the entire purpose of the procedure is to remove unhealthy nerves from your teeth!
Purpose of a tooth nerve
The purpose of teeth having nerves is to maintain the overall health of your mouth so that you can effectively eat and acquire nutrients. The nerves alert you of potential problems by sending pain signals whenever something is wrong with your mouth or teeth.
That is why infections and cavities feel painful. If there were no nerves, it would be painless and we wouldn't know that something is wrong. The problem would get worse and worse, eventually we would have no teeth because they got destroyed by infections or tooth decay.
The nerves are there to alert you so that you can intervene and stop that destructive process. You can think of it as a defensive mechanism that your body uses to preserve your teeth. That way you can eat properly and not perish from malnutrition.
Detect oral infections
The reason you're able to detect dental abscesses such as tooth abscesses and gum abscesses is because you have nerves in your teeth. Without them, you wouldn't even know that you've an infection in your mouth.
Being able to detect them early will permit you to get treatment for them earlier on. Waiting will only make it more complicated and more expensive to treat.
Detecting tooth decay
When cavities start to grow bigger, they begin to become more sensitive especially to sweets. A tell-tale sign of tooth decay is when you have sugar and your teeth feel sensitive.
If you get it treated early it may end up being a more conservative dental filling. However if you wait and let it fester, it could very well involve the pulp and you may need a root canal. That is significantly more involved and also more costly.
Takeaway
Of course your teeth have nerves because if they didn't, you wouldn't be able to sense food that is too hot or too cold. The whole point of having nerves in them is to alert you of potential problems so that you can treat them before they become catastrophic. It's how your body protects your teeth so that you can eat properly and get all of your nutrients.
Without teeth, you may become malnourished. Therefore you can think of it as a defensive mechanism to protect your overall health. Tooth nerve pain isn't just there to inconvenience you but to help you so that you can take action sooner to save your teeth.
