Are you about to get a dental crown procedure done for one of your teeth? Your dentist probably gave you a list of options for the type of crown material that you can choose from. Some of them had metal while others were all porcelain such as a zirconia crown.
Today we're going to talk about everything that you need to know about crowns made of zirconia. The good, the bad, the ugly, and how it stacks up against other types of dental ceramics. That way you can choose what is best for your tooth.
Table of Contents:
Overview
Zirconia crowns are marketed to the public as a dental ceramic that is all porcelain and metal-free. However, they're specifically made of zirconium dioxide (ZrO2) which makes it more accurate to call them a "ceramic steel."
It may get a little confusing so stay with us and read carefully.
Is zirconia a metal or a ceramic?
Zirconium dioxide (ZrO2) or "zirconia" as it is more commonly called, consists of one zirconium atom and two oxygen atoms. It is more of a ceramic steel rather than a metal or a ceramic.
Zirconium is a chemical element with the symbol "Zr" and atomic number "40" in the periodic table of elements. It is a very strong metal that is comparable with titanium (Ti) but it has a silvery white appearance.
Despite zirconium being a metal, zirconia crowns are made of a white crystalline oxide of zirconium. What zirconium oxide looks like is a white powder and that is what is used to make your dental crown.
As you can see, the oxide form of it certainly does not look metallic at all. It appears much more similar to a ceramic than a metal in this state. While it has a lot of ceramic properties in this form, you cannot disregard the fact that it was still derived from the metal zirconium.
In summary, your crown is technically a ceramic steel because it has metallic and ceramic properties. Appearance wise it certainly doesn't look metallic at all since it has a white color. For marketing purposes, it's often referred to as a ceramic dental material that is metal-free.
How is ZrO2 made?
According to Zircon Association, ZrO2 is naturally found in the mineral baddeleyite. It was named after Joseph Baddeley who discovered it while working on a railroad project in Rakwana, Ceylon which is now Sri Lanka.
Although zirconium dioxide can also be made from melting Zircon (ZiSiO4) at very high temperatures. Essentially zircon is mixed with coke and heated to beyond 2,800 celsius in an electric arc furnace. From there it will dissociate into zirconia and fumed silica.
Types of Zirconia Crowns
When it was first introduced to the dental community, only full zirconia crowns were available. However as technology improved, there are now three different types of zirconia that are available to restore your tooth with.
Attributes | Full Zirconia | Esthetic Zirconia | Layered Zirconia |
|---|---|---|---|
Cosmetics | Opaque | Translucent/Life-like | Life-life |
Flexural Strength | > 1000 MPa | > 900 MPa | Depends on layered ceramic |
Crystalline Structure | Tetragonal | Cubic | Tetragonal |
Yttria mol % | 3% | 4-5% | 3% |
Note: While the material is stable at high temperatures the same cannot be said for room temperatures. For zirconia to be stable at room temperature it does require the addition of metal oxides.
Yttria (Y2O3)
Ceram (CeO2)
What they look like:
Looks like any other type of crown except it is metal-less.
Tooth colored.
Full zirconia
A full zirconia crown is the first iteration of zirconium oxide being used as a crown material. Its most notable quality is its brawn over beauty since it's often marketed as being virtually indestructible.
Other names it goes by:
Full contour zirconia
Monolithic zirconia
Full strength zirconia
Framework zirconia
Tetragonal Zirconia (3Y)
Characteristics & traits:
Indestructible. Very strong and can withstand all sorts of heavy forces including teeth grinding at night.
Opaque-looking. When compared to traditional porcelain, it doesn't look as pretty since it lacks translucency.
Esthetic zirconia
Esthetic zirconia crowns were created due to a demand of wanting the full strength of zirconia but with better aesthetics. This was accomplished by increasing the yttria mol % from 3% to 4-5% and consequently the translucency of the material.
The increased translucency of this type of material made the crowns look more life-like. After all, natural enamel does have a certain degree of translucency to it which is how light passes through it. The opaqueness of full contour zirconia lacked that quality.
Other names it goes by:
Translucent zirconia
High translucency zirconia
Cubic-Containing Zirconia (4Y)
Characteristics & traits:
High strength. Despite the increase in translucency the material is still very strong. It is tougher than traditional porcelain and many other ceramic materials.
Translucency. The incisal edges of the crowns allow light to pass through due to its translucency. This gives it an improved cosmetic appearance which looks more life-like.
Preferred for anterior teeth. The better aesthetics makes it a better option for the front teeth.
Layered zirconia
The concept of a layered zirconia crown resembles the traditional porcelain fused to metal crowns (PFMs). Instead of fusing porcelain to metal, the layered zirconia would use zirconia as the base/framework and have porcelain fused over it.
Basically the substructure would be zirconia but a more aesthetic porcelain or ceramic would be "layered" over it to make it look prettier. This method of using the material is an alternative way of circumventing the opaqueness of full contour zirconia.
Characteristics & traits:
Improved aesthetics. The outer top layer uses a more aesthetically pleasing material. It could be with traditional porcelain or another type of glassy ceramic.
Not as strong as monolithic zirconia. Since it is made of zirconia and another material, it is not as strong as pure zirconia. As you may have guessed, the weakest point of the material is the junction between the two materials being layered together. Usually when it breaks, the most likely area to do so would be that junction of where it is layered.
When would I need a zirconia crown?
Zirconia can be used in any situation where a dental crown is needed but especially so if you need strength above all else. What it will do is protect your tooth and also restore it back to its original shape and function.
Conditions that may benefit from a zirconia crown:
Tooth decay. Moderate to severe tooth decay may compromise a tooth's structural integrity. A dental filling wouldn't be adequate for restoring the tooth.
Weakened tooth. Teeth that are prone to chipping and breaking may need a stronger restorative material. It is especially so if it's been repaired by fillings before but keeps breaking.
Extremely large filling. You can only fill a tooth so many times because it gets bigger each time. Eventually you will need to move onto the next step, which is a crown.
Broken tooth. A badly broken down tooth may still be repaired with a zirconia crown.
Root canal treated. One of the most common reasons for getting a dental crown is after a root canal. The tooth becomes more brittle overtime due to the loss of its blood supply when the nerve gets removed.
After an implant. After the dental implant gets placed and is ready for restoration, the material of choice is a zirconia crown.
Improve cosmetics. It can be used to change the shape and color of your teeth just like veneers. One such instance would be to cover up a grey tooth that is dead.
Severe teeth grinding. Those who are severe grinders may benefit from having their teeth restored with zirconia crowns. After all that is why one of the brands of zirconia calls their crowns Bruxzir crowns, which means it is meant for bruxism.
Pros and Cons
Every dental ceramic has its own set of advantages and disadvantages. That means zirconia is no exception because there are things it excels at and others where it falls short.
Advantages:
Strong. Can withstand heavy occlusal and chewing forces.
Metal-free. No unsightly metal margin since the material is white.
Good for bruxism. Those who grind their teeth heavily can wear down the tooth enamel. This material will protect it from excessive wear.
Longevity. Can last a very long time so it is resistant to breaking and fracturing.
Biocompatibility. Does not induce tissue inflammation like some other materials.
Same day procedure. Can potentially be made in a single day.
Disadvantages:
Opacity. Not as pretty looking as the ceramics that are high in glass such as emax or feldspathic porcelain.
Difficult to see recurrent decay. This material is highly radiopaque on x-rays. If a cavity is forming underneath you will have difficulty detecting it.
Masks problems. Due to its strength it can hide problems such as grinding until it is too late. If things break and go wrong there is a reason and cause. This makes it difficult to know for sure.
Not bondable. For short clinical crowns, choosing zirconia may risk the cap falling off a lot more frequently than a bondable ceramic cap.
Potential opposing tooth wear
There have been conflicting studies where some have shown that zirconia may cause excessive wear on the opposing dentition. The damage was higher than if a gold crown was used. They even recommended against its use in severe teeth grinding.
On the other hand there have also been studies which have shown that there is no harm to the opposing tooth.
6 month study found that monolithic Zr was comparable or even lower than other ceramics dental materials.
2 year study found no significant difference in enamel wear vs other ceramics.
The general consensus among the dental community is that unpolished zirconia can potentially be hazardous to opposing teeth. However if you polish it really well until it is glossy and smooth, there should be no harm. Perhaps that may explain why there are conflicting results.
What to expect for the procedure
Most commonly, there will be a total of two visits for the zirconia crown procedure. The first appointment will take roughly 45-60 minutes while the second will be 30-45 minutes. You may be numb for both them if your tooth is still vital/alive.
First appointment
Administer local anesthesia. Numbing gel and Lidocaine injection.
Crown preparation. Shave down the tooth to the appropriate measurements.
Pack cord. Place a thin cord around the gums to push them down and reveal the prepared margins. That helps in taking a more accurate impression of the prepared tooth.
Take an impression. Take a mold of the teeth with PVS or polyether. The impression gets sent to the dental lab for fabrication of the crown.
Fabricate a temporary crown. A temporary crown needs to be made in order to protect the shaved down tooth. The temporary will be glued in with temporary cement.
Pick a shade. The last but most important step is picking a color for your ZrO2 crown.
Second appointment
Administer local anesthesia. This is only required if you don't have a dead tooth.
Remove temporary crown. This is so you can try on the new restoration and see if it fits.
Clean residual cement. Old glue on the tooth may prevent the new one from fitting.
Try in the permanent crown. The try-in process is to make sure that it fits before it gets glued in. If it doesn't fit or the color is not right, it will need to be sent back for a redo.
Adjust the crown. If the new cap feels too tight, the contacts need to be adjusted. If the bite feels uneven, the occlusion will need an adjustment. Both of these can be done chairside by your dentist with a fine diamond football bur.
Polish. After all adjustments it is important to polish it so that it doesn't feel rough.
Permanently glue it in. Once everything feels good it is time to glue it in permanently with dental cement.
Zirconia vs other crown materials
As a dental ceramic, there are some things that it does well and others where it does not. Here is how it compares to other types of ceramics that are used for crowns.
Vs porcelain fused to metal crowns (PFM)
The porcelain fused to metal crowns (PFM) have been in service since the 1950s. It has served dentistry well and here is how it stacks up against the new contender, zirconia.
Attributes | Zirconia | PFM |
|---|---|---|
Esthetics | Translucent zirconia is comparable | Good |
Metal | No metal margins | Metal Margins |
Strength | Strongest | Weaker |
Single crowns | Yes | Yes |
Bridges | Yes | Yes |
Here is the infamous hammer test that demonstrates the prowess and strength of what zirconium oxide crowns can do compared to PFMs.
Vs emax crowns
Emax is a type of ceramic which has a mix of crystalline and glass structure. Zirconia is nearly purely crystalline only but that is what makes it stronger. However it is the greater percentage of glass that makes the emax look prettier.
Attributes | Zirconia | Emax |
|---|---|---|
Esthetics | Translucent is comparable | Good |
Metal | No Metal | No metal |
Strength | > 1000 MPa | |
Single crowns | Yes | Yes |
Bridges | Yes | Yes |
Vs porcelain crowns
All porcelain crowns is a very generic term but you can think of it as if it was similar to feldspathic porcelain which is used for veneers.
Attributes | Zirconia | Feldspathic porcelain |
|---|---|---|
Esthetics | Fair | Extremely life-like |
Metal | No metal | No metal |
Strength | Strong | Weak |
Single crowns | Yes | Yes |
Bridges | Yes | No |
How to take care of it
The wonderful aspect of crowns is whether they're zirconia, emax, or porcelain, you don't have to do anything extra to take care of it. You can treat it as if it was any other tooth in your mouth.
Brush and floss. You simply brush it and floss it like any other tooth. There is no special technique for brushing it. A manual or electric toothbrush will both work.
Fluoride toothpaste. The crown itself won't become decayed but the tooth underneath it still can. Therefore fluoride can help strengthen the tooth underneath of the cap.
Avoid hard foods. While you may eat whatever food you want but if you insist on using it to bite crab legs or open beer bottles, a mishap will happen eventually.
Dental check ups. Checking in with your dentist every 6 months is a good practice to have. They can evaluate the prosthesis to make sure it is working as intended.
How long does it last?
Zirconia is still a relatively new material that was only introduced recently so extended long term studies do not yet exist. Although we did find a 5 year study which reported a 98% survival rate for this crown material. That is certainly welcomed news since that makes it comparable to traditional PFM restorations.
Complications
There is no such thing as a product without any complications. Here are some which you can expect with this type of dental ceramic.
Need a root canal after. If the tooth dies after getting the crown, you may need to do the root canal through it.
Poor retention. Your zirconia crown keeps coming off despite being cemented with permanent glue.
Cost
The average cost of a zirconia crown without insurance is $1316.05 and that is according to the 2022 ADA survey of dental fees. However it can range from as low as $1025 to as high as $1688.
The exact cost will depend on the cost of living in your area. Although you should be aware that if you go to a very high end dental practice that caters to celebrities, it could be significantly higher than the estimates we've listed.
Cost with dental insurance
In our experience, most PPO dental insurances will cover about 50% the cost of a crown. That means you can expect a copay of about $658 on average. That is a good ballpark figure to go by if you need one and you have insurance.
Insurance downgrade
Even though we've said that insurance will most likely cover 50%, there are some that will downgrade you which results in a higher copay. Not all insurances want to cover an all ceramic crown because some will only cover an all metal crown.
If that is the case you will be responsible for the difference in fees if you opt for zirconia. If you choose to forgo it and get an all metal crown, there will be no additional cost.
Is it worth it to get zirconia?
While PFM crowns were the dominant choice in the 20th century, most patients and dentists have been moving towards all ceramic restorations like zirconia in the 21st century. Whenever patients are given the option, most would choose a metal-free one and thus zirconia wins over PFM on a daily basis.
Therefore if you want a tooth cap that doesn't have metal in it, ZrO2 would be a great choice. The question comes down to whether you are okay with metal in your mouth or not.
