Updated: Apr 28
Tooth decay that has progressed into the nerve of the tooth can absolutely cause headaches. The reason is your tooth nerve is connected to cranial nerve V (trigemnial nerve) which travels up to the brain and sends pain signals whenever a problem occurs with your tooth.
Due to the location of where the brain is, it is not unusual for you to experience a headache if you have a serious toothache.
In fact, a really bad toothache will often throb and give you a headache. That throbbing may be constant or it can come and go periodically. The symptoms may vary but it is definitely not a pleasant experience.
Symptoms of tooth decay into the nerve:
Throbbing pain - will feel like a heart beat that is pulsating.
Headache - can occur anywhere on your head.
Unbearable toothache - you would report this as a 10 out of 10 on the pain scale.
Sharp sensation - feels like a knife.
Constant pain - it won't stop bothering you at all.
Pain that comes and goes - it comes to hurt you periodically but goes away.
Feels worse when chewing on it - only hurts if you bite down or when you try to eat.
Wakes you up in the middle of the night - prevents you from sleeping because it is that severe.
Treatment for a headache causing cavity
Since the headache is a result of tooth decay affecting the nerve, it means that the nerve would require treatment. The procedure for curing an unhealthy nerve would be a root canal, which removes the infected nerve from the tooth.
Once the root canal is completed, you will need a dental crown made to protect the tooth. The reason is because the blood supply for the tooth gets removed along with the nerve. After the blood supply is gone, no more nutrients would supply the tooth and over time it will start to get more and more brittle. You can potentially risk fracturing the tooth if you don't put a crown on to protect it.
Not all cavities cause headaches
Just to reiterate, only tooth decay which has reached the nerve will have the potential to cause a headache. What that means is that all of the stages of tooth decay prior to reaching the pulp will not cause a headache. In fact smaller cavities often have zero symptoms and most people aren't even aware that they have them.
Earlier stages of cavities which do not cause head pain:
Enamel decay. The decay is contained within the outermost layer of the tooth, which is the enamel. This layer contains the largest concentration of the hardest substance in the body, which is hydroxyapatite and it is the reason why the cavity progresses slowly. All tooth decay begins by attacking and trying to penetrate through the enamel layer.
Dentin decay. Untreated enamel decay will progress into the next layer of the tooth called the dentin. This layer is softer than the enamel so the cavity will progress at a quicker pace once it gets here. The next layer of the tooth after the dentin is the pulp.
Why small cavities don't cause headaches
Tooth decay at its earliest stages are unable to induce a headache because it has not reached the nerve yet. The anatomy of a tooth is designed in such a way that the pulp is situated in the middle and protected by two outer layers called the enamel and dentin. This forces all decay to penetrate and work its way through these two layers first before they can get to the nerve.
Here is a diagram showing the anatomy of a human tooth:
As you can see, the outer most layer of the tooth is the enamel and that is where tooth decay has to start first. After that it progresses into the dentin and then finally into the pulp.
Once it goes into the pulp, that is where the majority of the nerve endings are. Your body will let you know if the decay is into there. Unprovoked pain or pain that wakes you up in the middle of the night is a tell tale sign that the cavity or infection is at the level of the pulp.
Can tooth decay cause dizziness?
Dizziness is a rare but possible side effect of very severe tooth decay. It can make you dizzy via two mechanisms, severe pain and infection spreading to the ear.
Severe pain. An unbearable toothache will make your head throb non-stop and that can seriously affect your mental state. It can cause you to feel dizzy and also make you see stars due to mental exhaustion.
Infection close to the ear. If the tooth decay ends up causing an infection, that infection can spread towards the ear. This is more likely if one of your back molars are affected because location-wise, those are the closest to the ear. Conditions which can affect the inner ear have been known to cause dizziness.
Tooth decay can certainly cause a headache but only if it is large enough to affect the nerve. Smaller cavities which are located in the enamel and dentin, are unlikely to cause a headache. In fact, they tend to have no symptoms at all.
Therefore if you have a headache and you suspect a cavity, it may be worthwhile to go in for your dental check up!
Author: Written by Dr David Chen, a general dentist in long island city.