Why multilayer zirconium blocks have developed rapidly in recent years？Perspectives from Experts at the 2024 South China Dental Exhibition

The rapid development of multilayer zirconia blocks in recent years can be attributed to several factors, as highlighted by experts at the 2024 South China Dental Exhibition:

1. Reduction in Porcelain Build-up: Multilayer zirconia blocks have significantly reduced the need for porcelain build-up, thus shortening the fabrication time for dental restorations and enhancing the efficiency of dental laboratories.
2. Since the incisal part of the multi-layer zirconium block is changed from glass ceramic powder (strength 100-200MPa) to zirconium oxide material (more than 600MPa), the overall strength of the denture restoration is improved, and clinically, the safety performance of the material is improved! Professor Teng Wei said, "The five-year clinical survival rate of multi-layer zirconia restorations is as high as 79-100%. For zirconia restorations made by the slurry stacking process, zirconia-decorated porcelain structure, porcelain chipping is the most common failure Case"
3. Reduction in Tooth Preparation: Due to the significant improvement in the strength and safety of multilayer zirconia blocks, dentists can noticeably reduce the thickness of dental restorations during tooth preparation. The required tooth preparation amounts for various materials are as follows：

   No.	Material	Anterior Tooth Preparation	Posterior Tooth Preparation
   1	3Y-TZP(Multilayer)	0.3mm	0.5mm
   2	4Y-TZP(Multilayer)	0.8mm	0.8mm
   3	5Y-TZP(Multilayer)	0.8mm	0.8mm
   4	Lithium Disilicate(GlassCeramic)	1.0-1.5mm	1.0-1.5 mm
   5	Porcelain-Zirconia	1.5-2.0mm	1.5-2.0 mm
   6	Metal-CeramicCrown	1.5-2.0mm	1.5-2.0 mm

4. The higher strength of multilayer zirconia blocks allows for reduced tooth preparation, providing the possibility of fabricating restorations for patients with limited intraoral space. Zirconia restorations can typically be fabricated with a thickness of 0.5 mm, which is unattainable with other dental materials such as glass and resin. Thinner restorations result in less tooth preparation, which is advantageous for both dentists and patients, as it preserves the long-term biological and structural health of the teeth to the maximum extent with minimal damage.
5. 
6. Improved Restoration Form: Among the three key elements of dental restoration fabrication—namely, restoration form, strength, and aesthetics—the most crucial is the restoration form. Multilayer zirconia blocks offer superior restoration form compared to porcelain-zirconia structures, as they are created using advanced CAD/CAM technology, resulting in restorations that require minimal post-processing for shape adjustment. Professor Liu Weicai pointed out that multilayer zirconia blocks can be used to fabricate fully anatomical dental restorations with excellent form, representing a significant aspect of zirconia blocks' integration into the digital dental industry.

7. In the field of ceramic veneer production, some companies claim that their zirconia ceramic veneers can achieve a thickness of 0.1mm  or 0.2mm, requiring almost no tooth preparation or minimal preparation. This aligns with the current concept of minimally invasive restoration, benefiting both dentists and patients.