A porcelain crown with a hairline crack is the beginning stage of a crown fracture which will most likely happen at some point in the future. Our dentists recommend being proactive and not reactive about this precarious condition.
Hairline crack in porcelain crown: Things to know
Appearance - faint crack line on crown
Causes - wear & tear or hard foods
Treatment - crown replacement
Consequences - crown fracture
What it looks like
A ceramic crown with a hairline crack will present with a very faint crack/fracture line that can run along any direction of the crown.
The photo below shows what it can look like on a molar crown.
Typically the crown is not considered fractured yet because it is still in one piece. However, you can usually visually see that there is a distinct line running through the porcelain.
Where the hairline crack can be located:
Chewing surface of the crown
On the sides (cheek or tongue)
The cracks can run vertically or horizontally
Essentially it can appear anywhere on the restoration.
Potential causes
Porcelain crowns can sustain a hairline fracture from eating hard foods, wear & tear over time, insufficient porcelain thickness, or to grinding.
Hard foods
Tooth caps are meant to protect your teeth but if you habitually eat very hard foods such as crab legs and etc, you will run the risk of damaging it. Typically the first sign of damage would be a hairline crack on the porcelain.
Wear and tear
Nothing lasts forever (except diamonds) and porcelain caps are no exception because over time you can potentially cause a hairline fracture. It may take a decade or two for it to occur but it depends on your lifestyle habits such as the type of foods that you eat and how well you take care of your teeth.
Thin porcelain
Very short molars may end up with very thin porcelain crowns that are more susceptible to hairline fractures. This is especially true for second molars for people with very short teeth.
The photo above shows a molar with a short clinical crown. A ceramic cap made on a tooth that small will be much thinner than normal. As you can imagine it will be more prone to breaking.
Teeth grinding
Severe teeth grinding can slowly wear away the porcelain on your tooth cap. It may start as a hairline crack and then progress to chipping on the porcelain.
As you can see in the photo above, a lot of the porcelain has chipped off but some of it still remains.
Can it be fixed?
Unfortunately, a porcelain crown with a hairline crack cannot be repaired meaning it will need to be replaced. In other words you will need a new crown made by your dentist.
What to expect replacing the hairline cracked tooth cap:
Administer local anesthesia.
Drill off the damaged cap.
Re-prepare the tooth to the proper measurements.
Pack cord to push away the gums for an accurate impression.
Take an impression of the teeth.
Fabricate a new temporary crown.
Pick a tooth shade.
Return in 1-2 weeks to cement the new crown.
The entire process is very similar to getting the crown the first time. The only difference is that you need to remove the old one prior to redoing all of the steps.
What to consider
In order to prevent this situation from reoccurring you may want to make a smarter crown material choice that is stronger and more resistant to fractures.
Stronger crown materials:
Zirconia. A zirconia crown has a reputation for having more brawn over beauty meaning that it is incredibly strong. If you need further convincing, just watch the infamous bruxzir hammer test video.
Gold. Porcelain crowns can fracture but gold crowns rarely do because the metal is malleable and has some give to it. Need convincing? Try dropping a porcelain dinner plate vs dropping a gold necklace on the floor. Which one will crack?
Consequence of no treatment
A hairline crack in a porcelain crown is not considered fully fractured or cracked yet but if left untreated it will become broken beyond repair.
The photo below shows a porcelain molar crown with a hairline fracture that runs across the chewing surface. It is very faint looking so you may need to squint your eyes a little to see it.
The photo below shows the same crown approximately 6 months later. As you can see the hairline crack became a full crack in the porcelain. The entire side of the porcelain is now missing because it cracked off! We believe the patient probably swallowed that fallen off piece.
In summary, if you leave this condition alone with no treatment, ultimately it will end up as a crown fracture.
Verdict
If you notice a hairline fracture on your porcelain crown you should contact your dentist. Our dentists in Long Island City recommend replacing it with a brand new crown because if you keep chewing with it, it will end up cracking in half anyway!
