Patients often ask if their tooth doesn’t hurt how it can have a cavity. Maintaining teeth is similar to maintaining a car engine. If you waited until your car engine showed symptoms (like seizing up) to change the oil, it would be a lot more time consuming and expensive to fix than if you took preventative action and actually performed routine maintenance. The same is true for teeth. if you wait until they hurt then it is usually far more difficult and expensive to fix them than if you fix them as soon as a problem is detected. Also, good health has been directly linked to good oral hygiene. This is why dentists recommend regular checkups where x-rays are taken periodically for early signs of cavities.

So, what is a Cavity?   A cavity is basically a bacteria filled hole in a tooth.  Cavities can be in a tooth that has a filling as well as one that doesn’t. A cavity can even begin at the margin of a crown.  Basically, anywhere bacteria can enter a tooth, a cavity can be formed.  It starts with microscopic damage to the surface of the tooth by acid secreting bacteria. Once enough surface of the tooth is dissolved by the acid, the bacteria can actually enter into the tooth, and does. At this point the bacterium continues to proceed deeper and deeper into the tooth attacking from the inside out. The attack of the tooth is uncontrolled because it cannot be cleaned. None of this is painful and may not even be sensitive. Rarely can it be seen without the help of x-rays. Once a hole has formed in the tooth, nothing (not even brushing, flossing, or fluoride) will stop this process except removing the decay and then covering the hole with a protective material (like a filling).

So, why can’t you wait until the cavity hurts to do anything about it?  Eventually, bacteria will penetrate very deep to the middle of the tooth and become infected causing extreme pain. The only way to alleviate the pain is to get the dead, rotten tissue out by either removing the tooth or by cleaning out the nerve inside the tooth (called a root canal procedure).
Once the tooth begins to die it is going to die. Therefore, if you wait until it hurts to fix it you are very likely to need a root canal procedure.  And, because after a root canal, the tooth becomes brittle it will need the protection of a crown and possibly a foundation for the crown since you have allowed the hole to become large. Worst of all, the crown that a young person gets (younger than middle age) is unlikely to last the rest of their life. It will most likely have to be replaced within 5-10 years depending on oral hygiene and lifestyle. If you had allowed the filling this could all have been avoided.

It is impossible to predict how long it will take a small cavity to go from just starting out to needing a root canal. Cavities progress at different speeds depending on diet, oral hygiene, and saliva composition and amount. Some may progress to tooth ache in just a few months and some may take years. Therefore there is no way to say “this tooth has a cavity but won’t need a filling until such and such date”.

So, next time your dentist says you need a filling, remember this post. I know the natural reaction is to think, “Yeah right, my tooth doesn’t hurt. This dentist just wants to make money off me.” Try to remember this post. The dentist actually makes a lot more money, if he or she let’s you wait until it hurts. A root canal, build-up, and crown cost a lot more than a filling. So if your dentist brings up your cavities early before they hurt, he or she probably has your best interests at heart.