If your crown falls off and the tooth looks black, it could be normal or it could be a cavity but you have no way to tell unless you get diagnosed by a dentist. If it is decayed, simply gluing it back on would be improper treatment.
Table of contents:
Why is the tooth black?
There can be many reasons as to why the tooth may have turned black underneath the crown but it has probably been darkening for a while. You were just not aware of the color change happening because the crown was covering over it. It's only after the cap of the tooth has fallen off that you can visibly see the black color.
Causes of black tooth with fallen off crown:
Root canal treated.
Dead tooth.
Amalgam staining.
Tooth decay.
What this condition looks like is a black colored tooth. It doesn't necessarily need to be pitch black in color, it just needs to be "darker" looking than your adjacent teeth. Therefore the color could be a lighter black, grey, or even a deep yellow.
Root canal treated
If the reason you needed a crown on the tooth was because it had a root canal, you should expect it to slowly turn black over time. This is because root canal treated teeth are considered dead which means it will discolor over time.
Therefore if it has been years since you've had the nerve removed from the tooth and the crown finally falls out... you can expect to see a black tooth.
The good news is that this condition is normal and not pathological. What it means for you is that you do not require any dental treatment for the darkened tooth but the fallen off crown will need to be recemented.
Necrotic tooth
A dead tooth will become discolored over time and they usually end up looking black in color. You probably guessed it but a treatment to mask the discoloration for a necrotic tooth is a crown. By placing a layer of porcelain over the tooth, it can hide the unsightly color.
The reason why non-vital teeth become discolored is because they have a non-functioning blood supply. That means it no longer receives nutrients and the remaining blood within the pulp chamber and canal will decompose. That decomposition is the reason for the color change.
Amalgam stained
Teeth that have or had large amalgam fillings in them can take on a dark appearance. The black color can leach out to surrounding tooth structure and cause it to discolor. Therefore if you had a large silver filling on that tooth but it ended up needing a crown, it can look black if your cap pops off the tooth.
Usually teeth with small conservative amalgam fillings do not have this problem. Then again, teeth with tiny cavity fillings also won't need crowns.
Decayed tooth
Last but not least, if you see a black tooth after your dental crown falls out it could very well be a cavity. Tooth decay was probably the one condition that you were most worried about when you saw the black color.
And your thinking is correct because the color of a cavity is often a brown to black color. Depending on the severity of the decay the intensity of the darkness will vary. A lighter brown color is usually not as severe as a very dark looking one.
How to tell if the black color means it is a cavity:
Deep black color.
Tooth looks soft or mushy. Healthy tooth structure is solid to touch.
Pieces of the tooth is disintegrating.
Foul odor. However, this isn't a definitive sign since most crowns smell very bad.
What to do
Depending on what is causing the tooth underneath the dislodged crown to be black, it may or may not need treatment. Not all of the conditions are pathological.
Cause of black tooth | Treatment |
|---|---|
Root canal treated | Reglue crown |
Dead tooth | Reglue crown |
Amalgam staining | Reglue crown |
Tooth decay | Excavate decay and new crown |
Reglue the crown
Absent of any tooth decay, root canal treated, dead, and amalgam stained teeth do not require additional treatment. The only thing your dentist needs to do is put a fresh layer of permanent glue in the crown and cement it back on.
The reason why it doesn't need extra treatment is because all three of those conditions are not complications. The overall tooth structure is still intact so nothing needs to be done for it.
Decay excavation with new crown
The only time the black tooth underneath the cap needs to be treated is if it was decayed. If there is a cavity underneath, simply reattaching the crown won't get rid of the decay. In fact, it will continue to grow and you may end up losing the tooth.
Your dentist will be doing you a misservice if they glue the cap on without treating the cavity.
The only way to treat this is to remove the decay parts and then restore it with a core build up or post and core. After that you will need a new crown to be made because the old one definitely will not fit.
When to see dentist
Even if that black color isn't due to decay, you still need to see a dentist. In fact you should seek professional care for all of the causes of the black colored tooth because you can't treat it at home.
Reasons to seek professional care:
You don't have access to permanent crown glue to cement it back on.
You can't tell if it is a cavity or something else.
For decayed teeth, it will need to be drilled out and only your dentist can do it.
If you leave the crown off for an extended period of time, it will not fit because teeth do shift. This is similar to how if you don't wear your retainers, it won't fit anymore.
Takeaway
A black tooth underneath a fallen off crown could mean that it was root canal treated, it was necrotic, stained by silver fillings, or it could be decayed. You won't be able to tell which one it is so you should see a dentist. Our emergency dentists in Long Island City are available for consultations if you're nearby.
