Zirconia crowns have grown more popular over the past few years — for good reasons. They’re extremely durable, and match the look of natural teeth well. Despite the hype, most patients do not know much about this type of dental crown. And some dentists hesitate to adopt it because they distrust hype, and they are comfortable with long-tested and understood materials such as porcelain and gold.
What is Zirconia?
Zirconia (zirconium dioxide) is a white, powdered metal oxide. Like other common dental crown materials, it is a ceramic. Zirconia is made from zirconium, a metal with similar properties to titanium. Zirconium makes a good choice for dental material because it is chemically unreactive.
Zirconia has many properties that make it a good choice for dental crown material. Some of these beneficial properties include:
- A natural, white color.
- High hardness.
- High fracture toughness (zirconia is difficult to crack).
- Resistance to wear.
- Resistance to oxidation.
- No chemical corrosion.
- Translucent appearance when sintered (baked).
Benefits of Zirconia Crowns
Because of these properties, zirconia offers many benefits to patients as a dental crown material. Zirconia crowns:
- Can be easily modified, reshaped, and recolored.
- Resemble natural tooth enamel due to their color and translucence.
- Do not require a metal base.
- Do not require as much of the original tooth be removed as with other types of crowns.
- Resist staining better than acrylic or composite ceramic crowns.
- Are biocompatible (they are safe to stay in the mouth a long time).
- Resist hot and cold temperatures well. Thus, they reduce the frequency of hypersensitivity associated with other types of crowns.
- Are extremely durable. Zirconia is about five times stronger than porcelain. Because of this, zirconia might be a better choice for patients who have had problems with other crown material or who have problems with grinding their teeth, excessively chew their gums, bite their nails, etc.
Another benefit to zirconia crowns is that dentists can make them in their office. Because zirconia crowns are milled directly from solid blocks of zirconia, they require less equipment, time, and materials to produce than other types of crowns, such as composite ceramic (porcelain and other ceramic material fused to a metal base). Dentists, therefore, can make them in-house without having to order the crowns from a dental lab. It is even possible for dentists to create and fit zirconia crowns in a single day.
If an order must go through a dental lab, it will take a few days or weeks before the finished crown arrives at the dental office. During the wait, the patient will have to wear a temporary crown. After the permanent crown arrives, the patient must then return to the dentist for a second appointment to fit the crown.
While the list of disadvantages to zirconia is short, it is worth noting. No material is perfect for everyone. It should also be noted that zirconia, while thoroughly tested in various industries, is a newer material for dental crowns than composite ceramic and metal. Fewer case studies have therefore been conducted on zirconia crowns than other types of crowns. Known disadvantages of zirconia crowns include:
- Limited translucence. Zirconia is not as translucent as porcelain or lithium disilicate (IPS) and therefore does not look as much like natural teeth as these other materials. Some dentists suggest using zirconia for posterior teeth (molars) and IPS for anterior (front) teeth.
- Greater difficulty detecting decay under the crown (because crown is so durable).
- Expense. Zirconia is generally one of the most expensive types of crown. However, the cost varies greatly from dentist to dentist.
- Dentists’ preferences. Some dentists prefer gold or composite crowns due to zirconia’s hardness. They may also simply be more comfortable working with crown materials they better understand.
How Zirconia Crowns are Made
The process of making zirconia crowns is far less complicated than the process for composite ceramic crowns. It starts at the dental office. First, the dentist makes an impression of a patient’s teeth. The dentist then sends this impression to a lab, where a technician pours die into the impression to make a mold of the teeth. The technician then cuts the mold into sections and scans it using a laser, red lights, or blue-light technology. Afterward, they upload the scan into a computer with CAD software that designs the crown. The technician may design the crown, as well.
These steps differ if the dentist has CEREC® technology available at their office. CEREC® manufactures a tool called an Omnicam, which dentists can use to scan patients’ teeth. No impressions are required. The scanned data uploads to a computer with software that designs the crown.
Both in the lab and with CEREC® equipment, technicians send the crown design from their computer to a milling/grinding machine. This machine reads the designs and creates the zirconia crown from a solid block of zirconia. A lab may send their designs to a factory to manufacture the crown, or they might mill the zirconia crown themselves.
After the crown is made, technicians (or factory workers) may add coloring to the crown. After this, they sinter it. Sintering refers to the process of baking a material at a very high heat (between 2730°F and 2910°F for zirconia) in order to harden it.
Once the sintering is finished, the dental technician textures, smooths, and glazes the crown. At this point, it is ready for the dentist to fit it in their patient’s mouth.
White River Dental in Columbus, Indiana, offers traditional crowns and single-day crown replacements with CEREC® technology. White River Dental uses the latest technology to care for its patients’ needs from 8 a.m. to 8 p.m. Mondays through Saturdays. Call now or contact us to book an appointment.