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Robert Elsenpeter is a freelance writer and frequent contributor to Dental Products Report and Dental Lab Products. He is also the author of 18 technology books, including the award-winning Green IT: Reduce Your Information System's Environmental Impact While Adding to the Bottom Line. As such, he’s particularly interested in the technological side of dentistry.
How to bring zirconia chairside with the CEREC SpeedFire Furnace.
Chairside dentistry is a convenient, value-added service. In just one visit-usually less than two hours-patients can walk out with a completed crown or bridge. While that is appealing, the services were somewhat incomplete because doctors could not offer zirconia in those visits. Zirconia restorations required the handiwork of a lab.
With the CEREC SpeedFire furnace and zirconia materials like CEREC Zirconia, however, doctors can extend their offering to include this strong, durable material.
Meeting a need
Patients at Willis Dental Care in Montgomery, Alabama, have come to expect same-day restorations. That swiftness would hit a speed bump, however, when Dr. Bradley Willis, DDS, prescribed zirconia.
“We’ve been a CEREC office for many, many, many years,” Rachel Taylor, Dr. Willis’s assistant, says. “So the ability to do zirconia bridges in-office now is an added benefit. We don’t have to send that out to the lab and wait on it to come back. Our labs do great work, and we were not displeased with the labs at all, it was just waiting time in getting the bridges back.”
Being a CEREC doctor, and seeing the need to offer same-day zirconia to his patients, Dr. Willis was eager to start using the CEREC SpeedFire.
“Up until the SpeedFire came out, we did not have the ability to sinter zirconia in the office,” Taylor says. “It was a process that used to take several hours in the lab, and now it can be done in just a matter of 30 minutes or less. That depends on the thickness of the restoration and the size of the restoration, but it’s usually 30 minutes or less. To be able to offer something like zirconia in one visit is amazing for us.”
Why zirconia matters
Other materials used in chairside systems, like ceramics, are certainly esthetic and durable enough when needed, but there are cases in which a stronger material is necessary, like zirconia.
“Zirconia is a harder material,” Taylor says. “For patients who are clenchers or grinders, who have broken other types of material, then zirconia is a good option.”
For Dr. Willis, zirconia is a great material, but cases could previously only be manufactured by a lab.
“Zirconia is the material that has always been attractive to dentists because of its durability, its fracture resistance,” Dr. Willis says. “It’s predictable and it’s reliable. The issue with using zirconia was that it would take a week-or even two-to get the restoration back from the laboratory. So, if you’re an office like mine, whose patients are accustomed to getting all their restorations in one visit, it made it difficult when you wanted to use zirconia. You were forced to have them return. Now I don’t have to do that. Patients can get the restorations in one visit.”
Zirconia is also well-known for its durability.
“Just drawing from our knowledge of zirconia from the last 10 or 15 years, and what a reliable material it has been, I have the confidence now that I can put the zirconia restorations on in one visit into patients’ mouths, who are maybe bruxers, heavy clenchers and grinders, and these restorations are durable enough to withstand the forces those patients are going to put on them,” Dr. Willis says.
Further, the material is forgiving enough to make Dr. Willis’s job easier.
“The beauty of zirconia is that it allows you more flexibility in the preparation of the tooth,” Dr. Willis explains. “The material can endure or withstand variations and nuances in your preparation techniques that other materials might not hold up against. I’ve always felt that CEREC makes you a better dentist in that when you see your preps on the screen over and over and over, blown up, magnified, you begin to modify your preps and improve your preps, because you’re seeing them in real time, in real life. But the zirconia material is much more forgiving, where some of the other materials are much more exacting in the requirements for thickness and contour of the preparation. Zirconia is a lot more forgiving in that sense.”
For the SpeedFire system, CEREC offers its own variation of the material-CEREC Zirconia.
CEREC Zirconia features a high flexural strength and is suitable for individual crowns as well as small bridges and can be processed in thin wall thicknesses. Since these restorations are manufactured in monolithic form, there is no risk of chipping. Another benefit for dentists is that zirconium oxide can be cemented conventionally.
“The advantage is we can now order zirconia that has the same strength and physical characteristics of some of the best known zirconias that have been on the market for 10 years,” Dr. Willis says. “We can just now deliver it in a matter of two hours.”
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How it works
The SpeedFire system follows the usual chairside steps: The patient’s oral cavity is digitally scanned and then the scan is transferred to an in-house computer where the restoration is designed (by either the doctor or a member of staff).
The SpeedFire system and CEREC Zirconia workflow differs slightly, because at this point, the zirconia is milled slightly differently than other materials. It is milled in an enlarged form and then densely sintered to its final size in the CEREC SpeedFire furnace.
Each CEREC Zirconia block has a unique serial number, telling CEREC equipment how large it should be milled, based on the shrinkage profile of each particular block.
“The new steps have to do with the fact that the zirconia is milled in an enlarged state to compensate for the shrinkage that occurs during sintering,” Dr. Willis says. “During the process of setting up your milling, you have to share with the milling machine a barcode, a serial number, on each zirconia block. That barcode then tells the software the properties of that particular block, so that it can be milled to compensate for that particular block’s shrinkage. It’s pretty amazing when you take into consideration that, thinking about each individual batch of zirconia can vary ever so slightly, the computer is compensating for that by knowing the properties of that particular batch.”
Adding zirconia to the chairside workflow is an important addition to same-day dental practices.
According to Dentsply Sirona, dentists can benefit from chairside systems because patients are drawn to those services. Eighty-three percent of patients in a survey said they prefer single-visit dentistry to traditional treatment. The majority said they would even be willing to pay more for single-visit dentistry. Two-thirds indicated they’d be happy to travel farther than they currently do in order to receive treatment in one session. Another two-thirds said they would even be prepared to change their dentist.
Reducing their number of visits to just one means less hassle for patients, especially when it would take at least a week for zirconia restorations to come back from the lab.
“Therefore, you would’ve been forced to place a temporary in the patient’s mouth and have the patient return for a second visit,” Dr. Willis says. “In our case, CEREC has always been about efficiency. In using CEREC for 20 years, my patients will say that they’ve gotten a bit spoiled by the fact that they can come in and get the restorative work done in a very short period of time. As all the materials have progressed, those times have been shortened. For instance, just yesterday we did a zirconia case, from prep to cementation, in an hour and 35 minutes.”
“Most, if not all, of the other major materials manufactured for CEREC can be sintered through this furnace,” Dr. Willis says.
“We like it because we can fire other materials as well,” Taylor adds. “We don’t strictly use zirconia. We use lots of other materials in-office, and it depends on what the patient needs.”
While chairside dentistry is a convenient option for patients, doctors were somewhat limited in what materials they could offer. With the SpeedFire Furnace, they can now offer zirconia and all its benefits in a single office visit.