You've got to be less sensitive about things!

One of the most common issues I see every day at Springhill Dental are people with sensitive teeth. These are people complaining of teeth hurting due to hot, cold, or sweet foods or drinks. I’m sure you have seen the commercials on tv for Sensodyne, Crest Sensitive, and all the other toothpaste brands trying to get you to buy their products. In this post I want to explain some of the most common causes of sensitive teeth and some ways you can reduce the sensitivity.

Let's talk tooth anatomy!

First off, what causes teeth to be sensitive. Well, let’s explain how teeth “feel” hot or cold. Let’s have a tooth anatomy lesson. A tooth has three layers:

1.       Enamel—The hard outer layer that acts to protect the dentin and pulp.

2.       Dentin—The middle layer which acts to support the enamel and as insulation over the pulp.

3.       Pulp—The inner layer which contains the nerves and blood vessels.



Cross section of a tooth showing the three layers.



When a person drinks hot or cold, this causes a change in pressure inside of the tooth. You can see this occur when a sealed plastic bottle is heated and it expands or if it is cooled and it contracts. This change in pressure inside of the tooth causes irritation to the nerve, which is transmitted as pain to the brain.

Now that we know how a change in temperature in the mouth can cause pain with a tooth, let’s talk about the possible reasons why a tooth would become more sensitive to these changes. Sometimes the reason people’s teeth or mouth is hurting is obvious. Sometimes though it takes some thought, and I have to go through a number of tests, x-rays, and lengthy exams in order to find the cause of people’s pain. I really enjoy this part of my job. I love that “Aha!” moment when I discover the culprit and find the cause of a person’s dental pain. Tooth sensitivity to temperature changes is often one of those problems that I have to play detective on to find the cause. (For the record I hate it for the patient! I don’t want anybody having dental pain and would be glad to spend every day looking at perfect mouths that don’t need any dental work.)

What's causing those teeth to hurt?

The first and most common is tooth decay. When a tooth develops a cavity, the enamel and dentin become weakened. This loss if insulation over the nerve can cause more sensitivity. How dentists treat decay is to remove all the weakened tooth structure and place a filling or cover it with a crown. If the decay goes untreated and enters into the pulp, this causes inflammation, which causes the nerve to become hypersensitive. Eventually this causes the nerve to die, causing the tooth to require a root canal or to have the tooth removed.

Another common cause of sensitivity is root sensitivity. This occurs when a person has gum recession. Recession occurs when a person loses bone and attachment around a tooth. The root of the tooth has less insulation over the pulp. It also has exposed dentin tubules. Ok, another dental anatomy lesson here. When the dentin develops, it’s actually not a solid block, but instead develops as tubes radiating out from the pulp. It’s a lot like Swiss cheese except the holes radiate from the center. The ends of the tubules are normally sealed by enamel.

This image shows the exposed tubules on the root of the tooth.
Sometimes nerve endings will radiate into the tubules.

However, there isn’t any enamel on the root, so these open tubules are exposed to heat, cold, and irritation from sugar, food, brushing, etc. There are a variety of treatments for root sensitivity. I personally like to start very conservative. This usually consists of using a combination of over-the-counter sensitivity toothpaste and prescription strength fluoride toothpaste. I have found this combination to be very successful. These two types of toothpastes will build a layer of insulation over the root, thus clogging the open tubules. If this treatment doesn’t work, my next treatment is to bond a filling over the root which seals the tubules and adds more insulation over the root. If this treatment doesn’t work, which is very rare, the tooth may need a root canal to remove the nerve from the tooth.

One other possible cause of sensitive teeth that should be mentioned is people grinding their teeth. Grinding your teeth can mildly irritate the nerve, causing them to become sensitive. Over time teeth are worn down from the grinding, thus reducing the insulation over the nerve. This also can cause sensitivity. I have even seen teeth that were worn down so bad from bruxism, the teeth abscessed and needed root canals or had to be removed. Usually teeth that are severely worn down require crowns to cover and protect the tooth. If most or all of the teeth are worn down, the patient may require full mouth reconstruction of their teeth and bite.



This poor person has a severe problem with grinding.
The only long term option is likely full mouth reconstruction or an upper denture.



There are other possible reasons that teeth can be sensitive. These include such things as cracked teeth or deep fillings and crowns. I plan on addressing both of these problems in future posts. If you have sensitive teeth, then I strongly encourage you to talk to your dentist about your problem. We dentists are here to help you with your oral health problems and want your teeth and mouth to look and feel the best it can.