Comparison of optical and crystal properties of three translucent yttria-stabilized tetragonal zirconia polycrystals with those of lithium disilicate glass-ceramic material

Chun-Cheng Wang; Po-Sung Fu; Jen-Chyan Wang; Ting-Hsun Lan; Pei-Ling Lai; Je-Kang Du; Wen-Cheng Chen; Chun-Cheng Hung

doi:10.1016/j.jds.2021.01.004

Comparison of optical and crystal properties of three translucent yttria-stabilized tetragonal zirconia polycrystals with those of lithium disilicate glass-ceramic material

J Dent Sci. 2021 Oct;16(4):1247-1254. doi: 10.1016/j.jds.2021.01.004. Epub 2021 Jan 29.

Authors

Chun-Cheng Wang¹, Po-Sung Fu^{1

2}, Jen-Chyan Wang^{1

3

4}, Ting-Hsun Lan^{1

3}, Pei-Ling Lai³, Je-Kang Du^{1

3}, Wen-Cheng Chen^{5

4}, Chun-Cheng Hung^{1

3

4}

Affiliations

¹ School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
² Department of Dentistry, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan.
³ Division of Prosthodontics, Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
⁴ Dental Medical Devices and Materials Research Center, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁵ Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, Feng Chia University, Taichung, Taiwan.

Abstract

Background/purpose: Among the ceramic materials used for all-ceramic crowns, zirconia has high biocompatibility and favorable mechanical properties, but its main drawbacks include low translucency and stress-induced phase transformation. To stabilize high-strength tetragonal zirconia polycrystal (TZP), 3-5 mol% yttria is usually added to prepare yttria-stabilized TZP (Y-TZP). In this study, the optical properties of three commercial Y-TZP ceramics were compared with those of the clinically available glass-ceramic material of lithium disilicate, and the relationship between translucency and crystal properties was analyzed in vitro.

Materials and methods: Twelve 5-mm-thick standardized disks were prepared from three Y-TZP ceramics and one lithium disilicate block. Absolute translucency was measured using a spectrophotometer with an integrating sphere. X-ray diffraction was used to quantify the main structural parameters (i.e., preferred plane, quantitative phase, and grain size) of Y-TZP crystals.

Results: The product-dominated phase of Y-TZP exhibited a tetragonal lattice pattern, and the preferred planes had minor variations. The diffraction patterns of the three Y-TZP ceramics demonstrated minor effects on translucency, without significant differences (p > 0.05). The grain size of 54-70 nm was negatively related to translucency in Y-TZP. Lithium disilicate specimens had significantly higher translucency than the three Y-TZP specimens (p < 0.001).

Conclusion: Grain size reduction played an essential role in developing highly translucent Y-TZP ceramics. The three Y-TZP ceramics were essentially opaque but exhibited poorer translucency than lithium disilicate in terms of esthetics.

Keywords: Lithium disilicate; Spectrophotometer; Translucency; X-ray diffraction; Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP).