When it comes to restoring a damaged tooth, zirconia crowns are among the top choices for dentists throughout the world. This is because of the lifelike aesthetics and durability of zirconia. Since this is a relatively new material, many patients are curious regarding the composition and uses of zirconia crowns. This article explains everything you need to know about zirconia as a material for making dental crowns as well as its pros and cons.

What is Zirconia?

Zirconia is a powdered white metal oxide of zirconium, which belongs to the titanium family. Therefore, zirconia possesses properties similar to titanium alloys. Just like most other crown materials, zirconia is also a ceramic material. However, zirconia crowns can be preferred over other types of ceramics for use inside the oral cavity because of their durability, chemical inertness and safety.

What are the Benefits of Zirconia Crowns?

As discussed earlier, zirconia-based crowns possess several advantages of the current metal-ceramic or all-ceramic based crown materials, which make them one of the best choices for making dental crowns:

1. Aesthetics

The most often used material for crowns are metal-ceramic crowns, that usually have a dark grey metal collar, or in cases where high strength is needed, the crown may even be a visible metal colour. Zirconia, being naturally white, offers a natural and aesthetically pleasant look to the crowns and other prostheses prepared from it. This is why zirconia crowns are the material of choice among dentists and patients when aesthetics and superior strength are required, especially when restoring the back teeth.  Due to these features, teeth restored with zirconia crowns are virtually indistinguishable from the natural teeth.

2. Milled Zirconia Crowns

Perhaps, the biggest advantage of zirconia crowns is that they can be prepared using the 3D printing and milling technology, which offers several benefits over the dental crowns prepared conventionally in the dental laboratory:

• Single Day Crowns – with the 3D printing and milling technology, highly aesthetic and durable zirconia crowns can be prepared at the dental chairside, and that too on the same day. So, you don’t have to wait for days or weeks to get your teeth restored as in the case of conventionally prepared crowns.
• Precision – with the 3D printing technology, digital impressions of the prepared teeth are made. Afterwards, these impressions are fed into a software to design to digitally design the crowns. Finally, the crowns are milled using CAD-CAM technology. As a result of this digital technology, the chances of errors and imperfections, which may be encountered during laboratory processing are eliminated and highly precise, durable and accurately fitting prostheses are prepared.
• Durability – zirconia crowns prepared with the milling technology contain fewer imperfections. Consequently, they are much more durable and last longer than the conventionally metal-ceramic or all-ceramic crowns.

3. Layering with Ceramics

Zirconia is naturally opaque. Teeth that have become darkened by trauma,  decay or after root canal treatment can be masked with zirconia to appear normal again after the crown. However, as it does not possess the translucency offered by ceramic crowns, zirconia crowns can be layered with translucent glass-ceramics to obtain the desired aesthetic outcome.

4. Strength

Zirconia is an extremely strong material and can withstand even the highest chewing forces generated inside the oral cavity. Unlike the metal-ceramic crowns, zirconia crowns are metal-free and do not require the placement of a metal layer beneath them.

5. Ease of Bonding

Zirconia crowns can be directly bonded to the natural tooth structure, thereby improving the retention and also making it a good choice in cases whereby the tooth is very broken down.

6. Natural Tooth Conservation

Due to the high inherent strength of zirconia crowns, they can be prepared in thinner sections in comparison to the conventional ceramic or metal-ceramic crowns. This is advantageous as less of the tooth needs to be removed to fit the crown in. More conservation of the tooth is better as there is more strength, and to reduce the risk of tooth sensitivity.

7. Safety

Zirconia crowns are biocompatible and completely safe for use inside the oral cavity.

The Other Side of the Picture

Despite the numerous benefits of the zirconia crowns, there are some disadvantages associated with this material as well:

• Opacity – as discussed earlier, zirconia crowns have less translucency. As a result, they tend to be less aesthetic than their ceramic counterparts and may not be suitable for restoring the front teeth.
• Abrasiveness – zirconia is an extremely hard material. Therefore, there are chances that the zirconia crowns may abrade the opposing teeth. This can be significantly decreased when the zirconia material is properly treated and polished.
• Cost – the cost of zirconia crowns is slightly higher than conventional crown materials due to their processing and material costs.

Zirconia Crowns at Dental Designs

At Dental Designs Clinic, we offer durable, aesthetically pleasant and natural-looking zirconia crowns to restore your teeth and to give you a charming and beautiful smile. With our technology, we are able to make these crowns with our in-house laboratory and can usually be issued on the same day.

Find Out More About Crowns Here!

References:

1. High-strength Cad/cam-fabricated Veneering Material Sintered To Zirconia Copings - A New Fabrication Mode For All-ceramic Restorations
   Florian Beuer-Josef Schweiger-Marlis Eichberger-Heinrich Kappert-Wolfgang Gernet-Daniel Edelhoff - (https://www.sciencedirect.com/science/article/abs/pii/S0109564108001486)
2. Clinical Trials in Zirconia: a Systematic Review
   K. Lyons-M. Swain - (https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2842.2010.02094.x)
3. Zirconia Based Dental Ceramics: Structure, Mechanical Properties, Biocompatibility and Applications
   Chandkiram Gautam-Jarin Joyner-Amarendra Gautam-Jitendra Rao-Robert Vajtai - (https://pubs.rsc.org/en/content/articlelanding/2016/dt/c6dt03484e/unauth#!divAbstract)
4. Restoring Primary Anterior Teeth: Updated For 2014
   Waggoner-William F. - (https://www.ingentaconnect.com/content/aapd/pd/2015/00000037/00000002/art00011)
5. Bonding To Zirconia Ceramic: Adhesion Methods and Their Durability
   Matthias Kern-Stefan Wegner - (https://www.sciencedirect.com/science/article/abs/pii/S0109564198000116)
6. Long-term Resin Bond Strength To Zirconia Ceramic
   S Wegner-M Kern - (https://www.ncbi.nlm.nih.gov/pubmed/11317401)

Dental crowns are used to restore the function and aesthetics of teeth that have been heavily damaged and to protect them from further damage. When a tooth has decayed, a filling can be placed if it is small. However, if the decay is large, there might not be enough healthy tooth structure to place a regular filling. This is when a crown will be better to have enough strength to protect the remaining healthy tooth structure for the long term.

If your dentist has recommended restoring one of your teeth with a crown, then you might find it difficult to choose a suitable crown material that best fits your dental needs and budgetary constraints. This article will give you an idea of the different types of crown materials available for restoring damaged teeth.

What are Different Types of Crown Materials?

Crown materials can be broadly divided into two types; metal and non-metal

Metal Crowns

These dental crowns are prepared from different metal alloys.

• Gold Crowns – gold alloy based dental crowns have been in use for restoring damaged teeth for a long time and might have seen some actors in old movies with “gold teeth.” Gold crowns provide an excellent balance between strength, safety and durability. However, their drawback is their metallic golden appearance, which may not be acceptable nowadays. Cost is also typically high, due to the rising cost of gold.
• Metal Alloys or PFM (Porcelain Fused Metal) Crowns – these crowns are typically made from a mixture of non-precious metal alloys in which the main ingredient is nickel, cobalt or chromium, that is then covered with a layer of porcelain to achieve a white appearance. The great disadvantage is that they need to be prepared in thick sections to allow space for both layers of metal and porcelain thickness. Therefore, they require extensive removal of the healthy tooth structure. This weakens the tooth further and can increase the risk of needing root canal treatment. Although it can appear white, it is usually easily distinguished from the natural tooth. Another one of their major drawbacks of porcelain metal crowns is the appearance of a dark silver metal line beneath the ceramic layer, which is quite unpleasant for many patients. Also, as the porcelain layer wears out over time, the underlying metal can be exposed and visible on the biting surface of the crown.

Metal Free Crowns

These crowns are made from tooth-coloured materials to provide lifelike aesthetics.

• Resin Crowns – these crowns are made from tooth-coloured polymer resins. They can appear similar to natural teeth. Over time, they will lose their polish and appear more matte. They also tend to be less aesthetic than their ceramic counterparts. Minor chips can be repaired immediately by the dentist. The main advantage of resin crowns is that very little or no tooth structure needs to be removed for the crown. The overall strength of the crown is lower than that of other materials but is still strong enough for normal use.
• Porcelain or Ceramic Crowns – The most beautiful and natural-looking option, they possess excellent strength, durability, and aesthetics. This is why porcelain crowns are one of the most commonly placed prostheses in the oral cavity. Ceramic crowns can be bonded onto the tooth enamel for extra strength and retention, and thus require less tooth structure to be removed. In fact, more healthy tooth structure can be conserved with ceramic crowns, instead of having to be drilled away for the crown.
• Zirconia Crowns – these crowns offer the best combination of strength, aesthetic appearance, and durability. They are white in appearance and similar to natural teeth. However, they are more opaque in nature, which makes them look slightly more bright in comparison to natural teeth. Zirconia crowns are very strong; they can withstand very heavy masticatory forces generated on the molar teeth. Also, they do not require the extensive sacrifice of natural tooth structure as they can be prepared in very thin (1mm) section.

Conventional Versus 3D CAD/CAM Crowns

Previously, dental crowns were prepared in the laboratory by using the impressions and study models of the prepared teeth. However, the prepared crowns were not always perfectly fitting, as there was still room for human error. For example, dimensional changes could take place in the impressions if they were kept in the open air for too long, or the distortion of the wax pattern of the prosthesis at any step. The impression quality also can vary depending on how deep the tooth margin or surface is. Also, problems could arise with the exact colour and shade matching of the crowns with the adjacent teeth, which meant multiple visits where the crown has to be sent back to be remade. Unfortunately, these drawbacks were more prevalent in traditional crowns as they required a higher number of steps for their fabrication.

We have the Perfect Solution!

Keeping these problems in view, we have introduced digital dentistry in our practice to maximize the accuracy and esthetics of our prostheses. Our state of the art CEREC system allows us to fabricate all-porcelain and zirconia crowns which not only possess naturally pleasing esthetics, but they also possess superior function and durability than conventional crowns.

How is our Digital Technology Beneficial?

You might be wondering why our digital CEREC technology is better than the conventional system, and how will it benefit you? Continue reading to find out:

• Accuracy and Precision – with our CEREC system, human error is greatly minimized. We will make digital impressions of your teeth which will be transferred to software that allows us to measure the material thickness, amount of space we have between the teeth and opposing teeth, shape of the crown to fit with the neighbouring teeth, the amount of biting forces on the crown, and fully customize your prosthesis so that it fits precisely over the prepared tooth.
• Natural Esthetics – our CEREC system possesses the capability to record the exact shade and colour of your adjacent natural teeth. This shade is then used while designing your prosthesis. As a result, we can accurately match the colour of our crowns with your neighbouring natural teeth.
• Same Day Solution – Conventionally, multiple appointments were required for the preparation of the crowns, and patients had to wait for many days or weeks before they could their crowns were received back from the laboratory. However, thanks to our 3D milling technology offered by the CEREC system, you can get a beautiful smile with crowns in just a matter of hours. We prepare the damaged tooth, make the digital impression, design the crown on the software and place the crown all in the same day!

At Dental Designs Clinic, our priority is to offer the highest quality dental care with our experienced dental team, and our state-of-the-art dental diagnostic and therapeutic equipment. During the consultation appointment, we will be discussing treatment options as well as material choices that will best suit your needs. To find out more about crowns, visit our page on veneers and crowns.

References

1. The Influence Of Different Core Material on the Fea-determined Stress Distribution in Dental Crowns
   Niek Jager-Marcel Kler-Jef Zel - (https://www.sciencedirect.com/science/article/abs/pii/S0109564105001624)
2. A New All-ceramic Crown: A Dense-sintered, High-purity Alumina Coping with Porcelain
   (https://www.tandfonline.com/doi/abs/10.3109/00016359309041149)
3. In Vitro Fracture Strength Of Teeth Restored with Different All-ceramic Crown Systems
   Narong Potiket-Gerard Chiche-Israel Finger - (https://www.sciencedirect.com/science/article/abs/pii/S0022391304005840)
4. Laboratory Simulation Of Y-tzp All-ceramic Crown Clinical Failures
   P.g. Coelho, E.a. Bonfante, N.r.f. Silva, E.d. Rekow, V.p. Thompson, 2009 P.G. Coelho-E.A. Bonfante-N.R.F. Silva-E.D. Rekow-V.P. Thompson - (https://journals.sagepub.com/doi/abs/10.1177/0022034509333968)
5. Fracture resistance and failure patterns of endodontically treated mandibular molars with and without glass fiber post in combination with a zirconia–ceramic crown
   (https://doi.org/10.1016/j.jdent.2008.03.014)
6. Anterior Esthetic Rehabilitation on Teeth and Dental Implants Optimized with Procera® Technology: A Case Report
   Pascal Bonnard-Marc Hermans-Philippe Adriaenssens-Philippe Daelemans-Chantal Malevez - (https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1708-8240.2001.tb00259.x)