Zirconium oxide was the focus of a TEAM talk from EADT eV. The interactive online format serves the targeted exchange of knowledge and lives from the participation principle. The participants are listeners and participants at the same time. The entertaining online talk is moderated by Carsten Fischer.

Zirconia. Question and conclusion

The focus of the second TEAM talk was on three central questions relating to the topic of “zirconium oxide”, which were discussed and discussed together with the participants. We summarize some of the key statements here for further reading. You will often find further links to relevant articles on our EADT website. These contain relevant literature references to scientific studies and publications.

Booked up! Insight into the second TEAM talk.

Keyword processing: What are the top 3 biggest sources of errors in dental laboratories and dental practices?

Fundamentally, not all zirconia is created equal. Today, we can look back on four generations, which differ in their mechanical and optical properties. The first two generations are tetragonally stabilized zirconia (3Y-TZP). These exhibit the highest mechanical properties and are frequently used for veneered zirconia frameworks . The third and fourth generations are cubic/tetragonal mixtures. Due to the cubic phase in the microstructure, the zirconia appears more aesthetic and translucent; however, its mechanical properties are significantly lower. Cubic/tetragonal zirconia are mostly used for monolithic restorations. Here, the restoration can be further individualized with ceramic materials through microlayering.

In a nutshell: zirconium oxide ≠ zirconium oxide!

Temporary fixation of zirconium oxide restorations

Through adequate planning and implementation in dental treatment (e.g. jaw relationship determination, framework try-in/firing try-in), temporary fixation of zirconium oxide restorations can usually be avoided. If the temporary attachment is loosened or unstable fixation, this can lead to possible crack induction and thus weakening of the restoration. Nevertheless, temporary attachment would be possible in many cases due to the higher mechanical properties. A short phase of testing, a so-called test drive, is particularly helpful in “difficult” patient cases.

In a nutshell: Temporary attachment is possible.

Abrasions on minimally coated restorations?

In vitro studies report rapid abrasion of the ceramic materials (microlayering) at the contact points, depending on the antagonist material. Abrasion at the contact points with the antagonist is also observed in clinical practice. Therefore, it is essential to ensure a smooth surface of the zirconia restoration before coating.

In a nutshell: Abrasion resistance depends on the surface and the antagonist material.

Sandblasting zirconium oxide?

Sandblasting damages the surface of zirconium oxide. Sandblasting with 50 µm aluminum oxide and a low pressure of a maximum of 0,5 to 1 bar can be used for cleaning and improving the wettability of the surface.

In a nutshell: Sandblasting with low pressure is possible.

Keyword aesthetics: full veneer or better micro-layering?

Monolithic restorations made from ceramic materials are becoming increasingly popular. From an economic and technical perspective, the question arises as to whether ceramic veneers are still up to date. Is the era of ceramic veneers coming to an end? From a scientific perspective, there are different approaches. On the one hand, the stability of the different ceramic materials and their indications as well as their aesthetic and light-optical properties in different oral situations are discussed. On the other hand, fractures (chipping) are the most common complications of ceramic veneered restorations.

Monolithic restorations made from ceramic materials offer good solutions. Different generations of zirconium oxide allow different options for finalization. Pay attention to the manufacturer's indication recommendations regarding the generation of zirconium oxide. The material thickness and pre-coloring of the zirconium oxide also influence the optical effect. Monolithic restorations often reach their aesthetic limits in the anterior tooth area or in difficult oral situations. The aesthetic and functional success therefore depends on many factors. The ceramic veneer or rather the “coating concept” must be economically and technologically oriented. Painted, veneered or minimally coated are the different approaches to adapting ceramic materials to the patient's oral situation. The time required for veneering or painting the ceramic restoration is an important component in the value chain. An alternative to “painting/glazing” or the classic “full veneer” is “microlayer technology” with a minimal coating of veneering ceramic. A thin (0,2 mm-0,4 mm) ceramic layer is applied here.

In a nutshell: Depending on the type of finalization, abrasion resistance can vary

Keyword hybrid zirconium oxides: What can we expect from the future?

Hybrid zirconium oxides are mixtures from several generations. Here, stability in the lower area and translucency in the occlusal area of ​​the blank are provided within a blank. 3Y-TZP materials are usually chosen for stability, while cubic (4Y-TZP or 5Y-TZP) zirconium oxides are used for aesthetics. A combination of cubic/tetragonal materials is also possible, with the translucent variant always positioned occlusally. With these hybrid zirconium oxides, the perfect positioning of the restoration in the blank is crucial in terms of stability. At this point in time, individual in-vitro studies are already available, but the scientific data is still very sparse.

In a nutshell: Hybrid zirconium oxides are finely tuned mixtures of different zirconium oxide generations.