By Hilarie Galloway, DMD
Introduction to Zirconia
Zirconia is a white, non-metal ceramic material that has become widely used in the replacement and restoration of teeth. Zirconia has physical properties that make it an ideal material for tooth replacement, including aesthetics, strength and durability, biocompatibility and resistance to wear and corrosion. Zirconia can be used in crowns, bridges, veneers, inlays, onlays, implants and dentures. As with all dental procedures, circumstances often dictate which material is most ideal in a particular case, and a dental professional can help to determine whether zirconia is ideal for your oral health needs.
Materials Used in Zirconia Teeth
Zirconium dioxide is a strong, white, ceramic material which has gained popularity in dentistry in recent years. Zirconium dioxide is often stabilized with other elements, such as yttrium, cerium, calcium, and magnesium. The addition of these elements contributes thermal stability and also changes the properties of the zirconia. For example, different zirconia materials are available with varying levels of yttria – adding yttria increases translucency, but with these improved esthetics comes the trade-off of decreased strength. There are currently many different formulations of zirconia on the market which allow the dentist to balance need for strength and aesthetics for each specific case. From dental crowns to implants, zirconia dental solutions offer flexible and dependable choices for patient care.
Advantages of Zirconia Teeth
There are many advantages to utilizing zirconium oxide materials to replace missing teeth or other dental restoration needs. A few primary advantages include aesthetics, durability and strength, biocompatibility, and resistance to wear and corrosion.
Aesthetic Benefits
Zirconia is a white, non-metal material. This serves as a great aesthetic option, specifically in comparison to traditional porcelain crowns or all-metal crowns. Since zirconia doesn’t require a metal substructure (as with a PFM crown), there is no metal margin show-through and no risk of graying at the gumline as often occurs with PFM crowns. In comparison to all-metal crowns, zirconia crowns allow for a much more natural tooth appearance since it is white in color (vs. metallic). Newer formulations of zirconia balance strength and aesthetics and provide improved translucency over previous zirconia materials. Zirconia can even be layered – somewhat like a PFM crown but with a white, zirconia base rather than metal – this provides the ability to hide unsightly dark staining on a tooth while still allowing for a more translucent surface to blend with natural, existing teeth.
Durability and Strength
Zirconia provides superior durability and strength when compared to other dental ceramics. It has the greatest hardness of any dental restorative material and has very high flexural strength. Zirconia is highly fracture-resistant which makes it a great option for posterior restorations and long-span bridges. This strength and durability also allow for long-lasting dental restorations which hold up well over time.
Biocompatibility
Numerous studies in humans and rats have shown zirconia to be a biocompatible material. Zirconia has not been found to cause cytotoxicity in rats or genomic mutations. Zirconia has even been shown to be less toxic to tissues than titanium for dental health. Furthermore, there is less bacterial adhesion and less biofilm formation on zirconia than on titanium, which promotes health in surrounding tissues and better outcomes for overall oral health.
Resistance to Wear and Corrosion
Zirconia’s physical properties make it resistant to acid erosion and physical wear. When placed opposing a different material (e.g. glass ceramic or natural enamel), zirconia is more likely to wear the opposing tooth than become worn down itself. When zirconia is smooth it is less likely to wear the opposing dentition. However, despite Zirconia’s erosion-resistant properties, it can become rougher in the presence of acid, which in turn can cause increased wear of opposing teeth (but not the zirconia tooth itself).
Disadvantages and Limitations of Zirconia Teeth
The use of zirconia materials to replace missing teeth has many advantages, but also has a few limitations. The main disadvantages associated with zirconia tooth replacement are cost, limited translucency, and challenges in adjustment and repair.
Cost
Given the many benefits zirconia affords, it is not surprising that a zirconia crown comes at a cost premium relative to other materials. In the case of single-unit crowns, zirconia crowns typically are more expensive than all-metal, PFM (porcelain-fused-to-metal) and even all-ceramic options. A typical zirconia crown often costs somewhere between $1,000 and $2,500 depending on geographic location, specific dental office, and complexity of procedure. It is important to note that this increase in cost often translates to longer lasting aesthetic restorations given the improved strength and durability of zirconia in comparison to other all ceramic crowns.
Limited Translucency
While zirconia is certainly a more aesthetic option than traditional PFM or all-metal crowns, it has limited translucency in comparison to more modern glass ceramics. This limitation has improved since the introduction of zirconia, when it was a very opaque, white material only suitable for use in posterior teeth. Now, with the addition of yttria content, high translucent zirconia can be better matched to the surrounding natural teeth. Despite these advances in zirconia, glass ceramics still provide superior translucency, while zirconia provides the balance of strength and aesthetics for tooth restoration.
Challenges in Adjustment and Repair
One disadvantage of zirconia restorations relates directly to the material’s hardness. While this hardness is ideal when the tooth is in use, it makes removing or adjusting a restoration much more challenging. Following minor adjustments to occlusion it is critical to polish zirconia restorations because rough zirconia can cause significant wear to opposing dentition.
Important Considerations
When selecting any dental material, it is critical to consider several factors, including patient suitability, preparation requirement and cementation/bonding considerations. Zirconia can be a great material for patients with a history of bruxism, but may not be the correct option for anterior restorations on a patient with extreme aesthetic demands and highly translucent natural teeth. Zirconia requires minimum reduction of 1.0-1.5mm occlusally, and 0.8mm wall thickness (though it is always important to check the specific zirconia material’s preparation requirements prior to fabricating a crown or submitting a case to a lab). Some zirconia materials can be made chairside using CAD/CAM machines and sintering units, while others are made in labs. Cementation best practices for zirconia restorations include sandblasting the internal surface of the zirconia restoration (or treating with Ivoclean), cleaning prepped tooth with pumice (not prophy paste) and treating with a desensitizer prior to cementing with a resin-modified glass-ionomer (RMGI) cement. When combined with an ideally retentive preparation, these cementation techniques should improve longevity of the zirconia restoration.
Applications of Zirconia Teeth
Given its superior physical properties, it is no wonder that zirconia makes for an excellent restorative material in a variety of situations. Single crowns can be made with great strength, and esthetic bridges without metal substructures can last many years using zirconia. Veneers can be fabricated with increased esthetics using zirconia with a higher yttria content. Zirconia dental implants help provide strong, long-lasting support for restorations on titanium implants. These implants can hide metal show-through using more opaque layered zirconia with a more esthetic zirconia on top. Full-arch hybrid dentures fabricated from zirconia provide a stable, strong, and esthetic arch replacement when attached to implants placed throughout the arch. Zirconia is even used in dental implants themselves, although their long-term success may be lower than that of titanium implants and this indication should be carefully considered on a case-by-case basis. Zirconia is an excellent restorative option for many dental scenarios, especially given the ability to balance strength and aesthetics with more recent zirconia materials.
Work with a Quality Dental Lab
Stomadent dental lab is here to help with all of your zirconia needs. Our lab fabricates beautiful zirconia restorations from individual dental crown and bridge units (Zirconia Crowns) to full arch replacements (Zirconia PMMA). When looking for a combination of strength, durability and esthetics, look no further than Stomadent’s zirconia restorations.
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