Choosing the Right Zirconia for the Job
Inside Dental Technology delivers updates on digital workflows, materials, lab techniques, and innovation in dental technology through expert articles and videos.
September 1, 2017
Volume 8, Issue 9, September 2017
Page(s): p. 60
Collaborative cases always begin with thorough analysis and planning. When choosing materials for the best outcome for each individual case, the process always begins by analyzing photographs and digital records.
One of the most important esthetic considerations for anterior restorations is the coloration of teeth that will be adjacent to the crown or implant. It can be especially challenging when those adjacent teeth are prosthetics themselves made with other restorative materials. Older zirconia restorations looked more opaque, which just wouldn’t look right next to a super-translucent crown made with the materials available today.
For example, for anterior implant restorations, many dentists default to prescribing screw-retained zirconia crowns. However, when a large amount of zirconia is in the restoration, the overall characterization of the tooth is difficult to match to a lithium disilicate crown or all-ceramic restoration. In that case, it may be better to use a zirconia hybrid abutment with a cemented crown fabricated with a restorative material similar to the adjacent teeth to ensure a good matching effect.
You can’t always prescribe zirconia or one preferred type of restoration. The big picture needs to be considered, as do the individual parameters, for choosing the right zirconia and restoration for each specific case.
Of course, strength is always a top concern, too. We all know that different zirconias are used for different parts of the mouth. But another determining factor is the minimal thickness of the material. Zirconia in general is very forgiving in margin and in tooth preparation style. Different types of zirconia may have different specifications as far as minimal thickness is concerned.
No matter what the material, early planning and continued communication are still at the heart of the best collaborations.
The evolution of zirconia happened along with dentists’ and laboratories’ move to digital dentistry. As the industry began shifting from analog to digital processes, zirconia came into favor, especially as the esthetics of the material continued to improve. Now zirconia has practically overtaken porcelain-fused-to-metal restorations.
With the newer generations of zirconia available, dentists and laboratories also need to update their processes and their own knowledge of what each variety can do. Though these differences may seem small, technicians need to work within the manufacturer’s indications for each material, especially the parameters for firing, cooling, etc. These “little things” can make the difference between successful restorations and those that are not successful.
When working on a case with a dentist, communication is paramount. The best way to do this is with images of the patient—including photographs using a camera or smartphone, intraoral scans, and, when possible, video, though that’s not used as frequently. These tools help the laboratory know what the current dentition looks like.
This is especially important when determining the appropriate zirconia for the anterior region. Occlusion is a major consideration, but, as Alan says, it’s also critical to see the dentition that will be adjacent to the restoration—whether it’s natural or has old restorations. This will help us decide on the type of zirconia to use to best match the existing color and characteristics, and be able to provide the most esthetic results for that patient.
Overall, zirconia has evolved tremendously over the last 15 or so years. Some early adopters were turned off by its optical qualities, and have been reluctant to try it again. These days, four to five generations down the line, it’s extremely esthetic. Dentists or laboratories that continue to ignore these benefits are really holding themselves and their patients back from better outcomes.
