Rhombohedral Phase Formation in Yttria-Stabilized Zirconia Induced by Dental Technical Tools and Its Impact on Dental Applications

• Published in: Materials Vol. 15; no. 13; p. 4471
• Main Authors: Wertz, Markus, Schmidt, Michael Benno, Hoelzig, Hieronymus, Wagner, Maximilian, Abel, Bernd, Kloess, Gert, Hahnel, Sebastian, Koenig, Andreas
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 24-06-2022; MDPI
• Subjects: CAM; Composite materials; Computer aided manufacturing; Degradation; Dental materials; dental zirconia; fixed dental prosthesis; Low temperature; Manufacturers; Optical properties; Partial stabilization; Partially stabilized zirconia; Phase composition; Phase transitions; Polycrystals; Preferred orientation; Prostheses; Sintering; Software; Surface temperature; Thermography; Transplants & implants; X-ray diffraction; Yttria-stabilized zirconia; Yttrium oxide; Zirconium dioxide; Oregon; United States > US; Germany
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15134471

In the study the influence of different dental technical tools on the surface temperature and phase composition of fixed dental prostheses (FDPs) made of yttria-partially stabilized zirconia polycrystals (3Y-/4Y-/5Y-PSZ) was investigated. FDPs were fabricated by using computer-aided manufacturing (CAM). The FDPs were treated with a contra-angle handpiece equipped with different burs and polishers. The resulting surface temperatures were measured with a thermographic camera, and the resulting phase transformations were investigated by X-ray diffraction and quantified by Rietveld refinement. Processing with burs resulted in no phase transformation, but a preferred orientation shift. Using coarse polisher induced a phase transformation to the rhombohedral phase, while fine polishers produced no relevant phase transformations and no preferred orientation shift. Compared to the monoclinic phase (ca. 9% theoretical volume increase), which is associated with low-temperature degradation (LTD), the rhombohedral phase is much more voluminous (ca. 15% theoretical volume increase) and distorted and, therefore, has a greater degradation potential.