Knowledge for laboratory and practice: Zirconium oxide and materials science are inseparable

Zirconia frameworks. The discolored dies are masked with an opaque zirconium oxide (2nd generation).

Materials science is just as indispensable in everyday dental work as it is in dental practice. Let's just look at the different zirconia materials available on the market. It quickly becomes clear that the knowledge once learned is no longer sufficient to exploit the full potential of zirconium oxide.

by Annett Kieschnick, Bastian Wagner and Nina Lümkemann

The different variants of zirconium oxide sometimes differ greatly in strength and translucency. The materials also differ in composition, microstructure and the resulting mechanical and optical properties, e.g. B. Bending strength/breaking load, fracture or crack toughness and translucency. Depending on the indication, the appropriate material can be selected in everyday laboratory life. Materials science knowledge is essential for this.

Materials details relating to zirconium oxide are important for dentists and dental technicians, e.g. b.

• to be able to select the appropriate material based on the indication,
• to be able to carry out material-appropriate preparation (preparation),
• to guarantee material-appropriate processing,
• to be able to implement the desired light-optical properties,
• to achieve the optimal aesthetic result,
• to choose the correct insertion protocol.

Case study from everyday laboratory life

In the present case study, six front teeth in the upper jaw were treated with all-ceramic crowns. The tooth stumps were slightly discolored. In order to mask the discoloration, a second generation zirconium oxide (high opacity, high strength) was used for the framework caps. The framework caps, reduced in an anatomical crown shape, were then individually veneered. The desired tooth color was relatively light; the crowns should radiate a natural translucency.

The balancing act between opaque framework material (discolored dies) and light tooth color could be achieved safely. For this purpose, after sintering, the framework caps were sprinkled with dentin material (bleach dentin) and then fired. This framework pretreatment made it possible to increase the brightness value of the ceramic restorations. Useful side effect: fine “microretentions” form on the surface of the framework, causing the incident light to be diffusely scattered. The crowns were veneered and finished according to the established layering scheme. It was inserted into the mouth using an adhesive approach, as recommended by materials science.

Fig. 1 Six front teeth in the upper jaw are to be treated with all-ceramic treatment.

Fig. 2 Digital photography with polarization filter to detect optical properties of light without reflections

Fig. 3 Zirconia frameworks. The discolored dies are masked with an opaque zirconium oxide (2nd generation).

Fig. 4 Sprinkling a framework cap with dentin powder (bleach dentin)

Fig. 5 The framework caps after firing form an ideal color background.

Fig. 6 Individual veneering with layered ceramic

Fig. 7 The all-ceramic crowns on the model appear lively despite the opaque zirconium oxide framework and have the desired translucency

Fig. 8 The zirconium oxide crowns were adhesively inserted into the mouth (cohesive, stable bond).

Conclusion
Auf dem 1st TEAM DAY of EADT eV The speakers will present a variety of facts about zirconium oxide and talk about their experience. The lecture by Bastian Wagner and Nina Lümkemann explains the symbiosis of laboratory, dental technology and materials science.