Can You Get A Cavity Under A Crown Or Filling?

Back a couple of years ago I was talking to my sister in law and she told me that she had recently been to her dentist and he found about 7 or 8 cavities under her old fillings. She asked me how she could possibly have cavities under her fillings. She thought that since the fillings were there that she shouldn’t get any more cavities, right?

After talking a bit more, I found out she was drinking a 2 liter soda every single day. She would sip on it all day long. She didn’t think it was a big deal until she found out about all these cavities.

Here is the deal. I see this all the time! You can absolutely get new cavities under fillings or crowns. In fact this is the single biggest reasons that they fail or need to be replaced. Every crown or filling has an interface where it meets your original tooth structure. Even with the best materials and techniques there is always going to be a microscopic gap in this area. Bacteria, food, and sugar can travel into this gap and cause a cavity over time if you’re not careful.

These cavities can be especially challenging because they are often much larger than the original cavity. In the case of fillings, these cavities usually don’t show up on the x-ray until they are quite large and have already compromised a large portion of the tooth. In many cases of additional decay under fillings a crown is needed to fix the tooth again. For teeth with crowns, new decay can cause you to need a root canal or even loose the tooth. Decay can often creep under a crown and your dentist can’t see it until it is too late. The crowns sometimes block the x-rays so that cavity isn’t visible until is huge or the crown falls off.

So if you’ve got crowns or fillings are you already doomed? Is it just a matter of time? 

No! I’ve also seen fillings and crowns that have been in people’s mouths for over 50 years! This is with the old materials that they used 50 years ago. What did all these people have in common? A good diet and good oral hygiene. They avoided consistent exposure to sugar and kept their teeth clean. In most cases they flossed regularly.

Want to avoid more dental work. Doing what all these people did. Limit sugar. Brush and floss your teeth. Avoid bad habits. This doesn’t mean that at some point you won’t need more dental work. Fillings still wear out and teeth break. If you do these things though you increase your odds of keeping those fillings and crowns as long as possible.