What Are Dental Crowns?
A dental crown is a cap made of an artificial material used to cover all the tooth surfaces to restore its strength, function, and appearance. They are usually placed on damaged, broken, or root canal-treated teeth, and when a tooth or a few teeth are missing, joint crowns or otherwise known as a dental bridge, are used to replace them. Also, crowns can be used on top of dental implants for the same reason.
Dental crowns have been in use for many decades now. Traditionally they were made from gold alloys, nickel, or cobalt-chromium alloys. Later, tooth-colored material known as dental ceramics was added on top of these alloys to make the dental crown appear like a tooth. But the presence of metal underneath the ceramic always made it difficult to give a life-like appearance to these crowns. The opacity of the metal was always shown, and it was hard to match the translucency of the natural teeth.
In order to solve this problem, dental crowns were made out of ceramics entirely. The initial version (Lithia disilicate crowns) was esthetically superior, but they lacked the strength. There was always an issue of fracture of these crowns, and there was a show-through of discoloration of the underlying natural teeth. Also, they were not useful for bridges replacing many teeth. Then came the revolutionary material Zirconia (Zirconium oxide) in the dental arena.
What Are Zirconia Crowns?
Zirconia combines the advantages of strength and a life-like appearance. It is light as well as strong, making it an ultimate choice for dental crowns. It is also chemically inert and resistant to corrosion. Zirconia can be used as dental crowns, bridges (even for replacing all the teeth in the jaw), dental implant crowns, abutments (supporting structure for dental implants), and even as dental implants themselves.
Advantages:
1. Metal-Free - As mentioned earlier, there is no metal included in the crown, which essentially makes the mouth metal-free.
2. Precise Fit - The Zirconia crowns are custom fabricated for the particular patient’s tooth size using CAD-CAM technology. The scanned image of the patient’s tooth will be fed to the computer, and the Zirconia crown is first designed in the computer to have an accurate fit. Then the design is transferred to a computerized milling machine which mills the exact design precise to microns. This makes sure there are no problems related to gap formation and food lodgment in the crown areas.
3. Quick - Since the entire process is carried out by computer design and milling, it does not take days together to fabricate them. A crown or bridge will be ready within hours of taking the measurement, which essentially means fewer visits to the dentist.
4. Longevity - With the kind of precise fit achieved with these crowns, naturally, the lifespan of these crowns will be higher than that of their counterparts. There will be zero issues pertaining to gap formation between the crown and the tooth on which it is fitted, making them long-lasting.
5. Strength - The strength of Zirconia crowns can be equal or sometimes even more than that of the natural teeth. This makes them almost impossible to break during normal function.
6. Life-Like Appearance - In the beginning, Zirconia crowns were considered opaque and not very esthetic. But the current versions have a good amount of translucency, making them esthetically close to the natural teeth. They are also good at covering up natural stained teeth, unlike the Lithia disilicate crowns. This makes it impossible for the observer to differentiate between the natural and artificial tooth, thereby enabling the wearer to smile freely without being conscious about his or her dental crown.
7. No Greying Effect - There might be a grayish discoloration along the neck of the tooth when metal-ceramic crowns are used. This is simply due to the presence of metal, and it is harmless. But when this happens in the front teeth region, surely this will not be a pleasing sight. With the use of Zirconia crowns, this problem can be solved completely.
8. Light Weight - Sure, these metal-free crowns are much lighter than the metal crowns and metal ceramics, making them comfortable for the user. There is no feeling of “heaviness” on the teeth with these crowns.
9. No Chance of Ceramic Separation - The ceramic portion of the metal-ceramic crowns frequently separate from the underlying metal core making an unaesthetic appearance. This does not happen with Zirconia crowns, as the entire crown is made up of ceramic-related components.
Disadvantages:
1. Expensive - Zirconia crowns are usually more expensive than metal-ceramic crowns. But, considering the life span they can serve, this should not be a big factor.
2. Not Versatile - There are certain conditions where there will not be enough space to fabricate Zirconia crowns.
What Are the Types of Zirconia Crowns?
1. Regular Zirconia:
This type has a Zirconia core and regular ceramic (feldspathic) on top. This can be used in front teeth and premolars where chewing forces are moderate.
2. Monolithic:
This type is used only for back teeth crowns where limited space is available for crown placement. These crowns are unsuitable for front teeth crowns.
3. High Strength Zirconia:
This type is used for the back teeth crowns and where multiple teeth have to be replaced with a dental bridge. These types can even replace the entire set of teeth in a jaw.
4. Zirconia for Bruxers:
Bruxers are people who grind their teeth at night and have heavy biting forces. For such patents, there is a special type of Zirconia with very high strength.
5. Translucent Zirconia:
This is also a special type of Zirconia used only for the front teeth with high levels of translucency. This is especially used for young patients.
Are Zirconia Crowns Safe?
They are extremely biologically compatible and do not cause any reaction in the body. In fact, they have even been used as hip bone implants for so many years. So far, no allergy has been reported for Zirconia crowns.
How Long Can the Zirconia Crowns Last?
A well-made zirconia crown has the ability to last at least 15-20 years with good maintenance from the patient such as,
-
Regular flossing.
-
Brushing.
-
Regular dental checkups.
-
Professional cleaning.
Can Existing Metal Crowns Be Replaced With Zirconia Crowns?
That is definitely possible, albeit being a difficult procedure. The existing crown has to be carefully removed by the dentist without damaging the underlying teeth and then can be replaced with a Zirconia crown.
Are Zirconia Crowns Only for the Front Teeth?
They can be used for back teeth as well. In fact, they can practically be used to replace any tooth in the jaw.
Conclusion:
The advent of this marvel material for dental crowns has led to the transformation of the way one can look after dental treatment. With so many options available in Zirconia today, the dream of a perfect smile is not very far. The amount of confidence boost one can achieve with this smile is priceless.
