A dental crown is a restoration that completely encircles the tooth structure or implant abutment and looks exactly like a natural tooth.
A dental crown or cap (layman’s word) can be fabricated with a variety of materials such as metal alloy or porcelain or commonly a combination of the two. Once it is fabricated just like a tooth and verified its fit by a dentist, the crown gets cemented with dental cement on the tooth.
A crown protects the tooth from bite forces that can destroy a tooth and lead to extraction. The protection is similar to the way a thimble protects a finger while sewing. It’s a durable cover.
The teeth that need crowns are not healthy.
While some tooth reduction is necessary to place a crown, not placing the crown can be worse. Crown placement generally extends the life of a tooth.
Why would you need a dental crown?
1. When there is too much tooth structure missing due to tooth decay or trauma
If there is too much tooth structure missing due to gross decay or trauma, there is often no other way to restore to tooth but put a crown.
2. Cosmetic purposes when veneers or bonding is no longer possible.
When there is a lot of tooth structure missing and/or structurally not durable to do veneer or bonding, a crown is indicated. Sometimes teeth have old silver fillings – where the tooth has become discolored from the filling.
Simply placing tooth colored fillings in these teeth doesn’t always make it look better. Sometimes covering the tooth with porcelain is the only way.
3. After root canal therapy on the tooth (dramatically reduces the risk of fracture)
Teeth sometimes need root canal treatment to be saved. Teeth are weakened after a root canal and more brittle than a vital tooth.
Crowns on root canal treated teeth substantially improve the tooth’s resistance to fracture.
It’s notable that if a root canal tooth fractures, it cannot necessarily be fixed, necessitating extraction. At that point, it’s too late to do a crown.
The root canal itself relieves the pain, but treatment is not yet complete on the tooth. Crowns are indicated in a timely manner after the root canal.
In some teeth after a root canal treatment, the tooth becomes gray in color. A translucent all-porcelain crown is not indicated for these cases.
On the contrary, the opacity of metal or opaque ceramic can be used to mask the gray color and surface porcelain is used to make it look natural again.
4. When there are fracture lines or actual fracture within the tooth.
Sometimes you cannot see the crack in the tooth but feel sensitive. The hairline crack can be prevented to become a full-blown tooth fracture if you have a crown on it to protect.
5. On a selective basis to protect a weakened tooth.
This is for certain teeth, when Dr Oh or Dr Estafan sees a tooth that appears as if it will fracture imminently. These teeth typically have large fillings, perhaps some craze lines (like cracks in a windshield) combined with a heavy bite.
Obviously we can’t predict when these teeth will fracture, but waiting until the fracture happens means taking the risk that it would need more than just a crown (e.g. root canal or crown lengthening) or worse – sometimes we can’t fix a fractured tooth and it needs to be extracted.
At that point, we – and patients – wish we had done the crown when it looked poised for fracture.
6. Teeth are worn out from years of grinding.
A small number of patients have such a heavy bite that they wear their teeth out through their every-day habits of chewing food and grinding their teeth.
These patients have many or all teeth that appear to have been ”sanded down” In extreme cases, the slow tooth destruction over time can lead to a loss in the vertical height of the lower part of the face. The distance from the nose to the chin is effectively less than in health.
These patients typically need crowns placed on all the teeth (or all of the top teeth or all the bottom teeth) in order to properly restore form and function. This is referred to as a fixed reconstruction – and it’s best done by a prosthodontist.
7. Specific medical conditions like Amelogenisis Imprefecta, Bulimia, Acid Reflux or Ectodermal Dysplasia.
These conditions are not common, but they leave teeth in a weakened state that doesn’t hold up over time.
It’s typical that these people will need most or all of their teeth crowned to prevent fracture/decay of the weak teeth.
These people also need to take extra care of their teeth, perhaps with more frequent checkups/cleanings and X Rays in addition to fastidious home care to keep their smiles healthy over time. It’s also important to see a dentist who has seen and treated cases like these before.
Prosthodontists have the experience necessary to recommend these treatments only when indicated and execute them efficiently.
How is a dental crown fabricated?
A crown is customarily made at a dental lab, although it can be fabricated by machines or at a lab at the dentist’s office. More and more the 3D printing technology(CAD-CAM) is used to fabricate the crown with tooth-colored material.
What are the different types of a crown?
Temporary Resin Crown
Temporary crowns are usually made chairside by a dentist or lab technician. They are not meant to last definitively but rather on an interim basis. While the definitive crown is made at a lab (the turnaround time can take 1-2 weeks), patients usually wear temporary crowns.
Stainless Steel Crown
Stainless Steel Crown is typically used in pediatric dentistry for primary teeth. These crowns are done on the primary molar to prevent non-restorable decay. They can protect decayed primary teeth and maintain the arch space until they are exfoliated.
Full Metal Crown
All-metal crowns (like gold crowns) are extremely durable and very healthy in the right areas, but they have fallen out of favor in the eyes of patients because they do not look as nice as the tooth-colored ones. Gold crowns are very strong – which means the dentist doesn’t need to cut away as much tooth. They are biologically well tolerated by gums and soft tissues in the mouth (gums typically stay healthy when in contact with gold). Gold is hard, but not abrasive to other teeth. This is why you see gold when you look in the mouth of a dentist 🙂
Porcelain Fused Metal Crown
The standard of care for many years has been a combination of metal and porcelain or PFM (porcelain fused to metal). When done well, this combination creates an excellent mix of strength and esthetics. However, the esthetics of these crowns are generally not as good as all-porcelain crowns.
Light doesn’t pass through metal alloys they way it does most porcelains. Teeth themselves are translucent – they get their white opalescent look from the tooth structure, the tissues around them and the light which passes through them. Compared to opaque metals, all-porcelain crowns are usually the most esthetic option. Porcelain, however, is also the most brittle of all the crown materials and can break with heavy bite forces. Bite forces are greater on back teeth where esthetic demands are low. Since bite forces are least on front teeth, where esthetic demands are highest, front teeth are perfect for all-porcelain crowns.
Full Contour Zirconia Crown
Zirconia is the hardest known porcelain and the strongest material used in dentistry. Since the zirconia crowns get milled rather than layered like traditional porcelain material, CAD/CAM technology is used to fabricate. Although they can be made white in color, they are much more opaque in color. Indications of Zirconia crowns are for the molars due to the opaqueness.
Lithium Disilicate Crowns
These are far stronger porcelain crowns than the conventional felspathic porcelain. These can be also 3D printed or milled. They are also much more esthetic than zirconia crowns and often used on premolars and front teeth where indicated.
How Much Does a Crown cost?
A cost of a crown can range from $1200 to over $2500, depending on the area (the metropolitan area is more than rural area) and the materials and laboratory service. Crowns are not cheap, but well-done crowns can save teeth for many years.