It is possible to get tooth decay under a filling because the decay can enter into the gap between the filling and your natural tooth structure. This condition is called recurrent tooth decay since it is not the first time that it happened.
Here is a picture of a cavity underneath an existing filling:
There is a microscopic gap that may form where the filling meets the natural tooth structure. If a cavity were to form, the most likely point of entry would be that gap or junction between the filling and the tooth. From the photo you can see a lot of discoloration around that junction, which is the entry point for the decay.
In case you were wondering if you have this condition called recurrent tooth decay, this article will explain everything that you need to know about it. We'll also let you know what you should do!Good oral hygiene
How to tell if you have tooth decay under a filling
The only way to tell if you have decay under a filling is to get it confirmed by a dentist. Nonetheless, if you have any of these signs or symptoms, you should go in for a check up because you may have it.
Sensitivity to sweets. You may get a zing or an unpleasant sensation if you eat anything sweet with sugar in it.
Discolored filling. Your tooth filling looks like it is changing colors. Usually if decay sneaks in under the existing filling, you'll see a black shadow coming through the restoration.
Here is a photo showing what decay under a filling in a premolar looks like:
Here is a photo showing a more advanced cavity inside of a broken filling. This can happen if you don't take care of the cavity under a filling. It can eventually cause a hole in your tooth.
When the decay gets to the point where it can cause a hole next to the old filling, it will definitely be sensitive. The reason is because the dentin, which is much more sensitive than the enamel will be completely exposed to the outside elements. Of course this is all a part of the progression for the stages of tooth decay, small cavities progress through the tooth to become bigger ones.
Why does recurrent decay happen?
Recurrent decay under a filling can develop from new decay in the gap, de-bonding, or the existing filling breaking.
New decay. The filling itself may not be able to get a cavity but the natural tooth structure immediately next to it can. Decay can form at that junction where the filling meets the tooth.
De-bonding. The tooth colored fillings are bonded onto the tooth. If that bonding melts away, decay can sneak in and start forming.
Broken filling. A filling that is fractured or damaged is a prime spot for tooth decay to develop. This is why it is important to get any damaged restorations replaced as soon as possible.
Treatment for a cavity under a filling
Since there is decay under the filling, the cavity will need to be removed first and then replaced with a new filling. However, depending on the extent of the decay, a cavity filling may not be enough and you may need a crown or even a root canal sometimes.
Small decay under filling. Another dental filling should be sufficient to restore this tooth back to normal. Don't put it off because the cavity can grow and you may need to move onto the next treatment.
Medium size decay under filling. If the cleaned out cavity will encompass more than 50% of the entire tooth, you may need a dental crown. A crown will offer better structural integrity than a large filling. An analogy would be patching up your pants if there was a hole. However, if you were missing an entire leg on your pants you may want a new pair!
Large decay under filling. If the cavity is very big, it could very well be close to the nerve. In that case you will need to treat the nerve by removing it via a root canal procedure. Afterwards you can get a crown to protect the tooth.
How to prevent it from happening again
As you are now aware, fillings can get decay underneath them so just because you get a cavity filling, it does not make it immune to new decay. The only way to prevent it from happening again is to maintain good oral hygiene and minimize the sugar intake.
Good oral hygiene. If you want acknowledgement from your dentist, you must practice good oral hygiene. This means you should brush for at least 2 minutes twice a day and then floss before you go to bed.
Minimize sugar. Reducing or even eliminating sugar from your diet will do wonders to prevent cavities from coming back. The reason is because the bacteria which cause them require sugar as a fuel. If you deprive them of it, they won't be able to cause any damage to your teeth.
Yes, you can certainly get a cavity under a filling because new cavities can attack the gap in between the tooth and filling. Therefore, even after getting a cavity filling you should still be diligent with maintaining your oral hygiene and minimizing sugar intake. That is the only way to keep cavities away.
Author: Written by Dr David Chen, DDS a long island city dentist.