Impact of different pretreatments and aging procedures on the flexural strength and phase structure of zirconia ceramics

Kelch, Matthias; Schulz, Julian; Edelhoff, Daniel; Sener, Beatrice und Stawarczyk, Bogna (2019): Impact of different pretreatments and aging procedures on the flexural strength and phase structure of zirconia ceramics. In: Dental Materials, Bd. 35, Nr. 10: S. 1439-1449

Abstract

Objective. To test the impact of zirconia pretreatment and aging on flexural strength and phase structure. Methods. For flexural strength measurements, 180 3Y-TZP(0.25) specimens were fabricated and pretreated: (i) air-abraded (105-mu m alumina, 0.25 MPa), (ii) air-abraded (50-mu m alumina, 0.25 MPa), (iii) air-abraded (30-mu m silica-coated alumina, 0.28 MPa) (iv) non-pretreated. Each pretreated group (n = 15) was aged: (a) hydrothermal (134 degrees C, 0.23 MPa, 2 h) (b) in a mastication simulator (1,200,000x, 5/55 degrees C) and (c) not aged. The fractured specimens were stored dry for 5 years (23 degrees C) for analysis of phase transformation. Additionally, specimens were fabricated from 3Y-TZ1D(0.25) (n = 12) and 3Y-TZ1D(0.05) (n = 8), pretreated (i, ii, iii, iv), and hydrothermally aged. Each air-abrasion method was alternated using 0.05, 0.25 and 0.4 MPa pressure. The phase transformation was examined by Raman spectroscopy and surface topography by scanning electron microscope. Data were analyzed using univariate ANOVA with the Scheffe post hoc test and partial-eta-squared (eta(2)(p)) (alpha = 0.05). Results. The highest impact on flexural strength was exerted by the pretreatment (eta p(2) = 0.261, p < 0.001), followed by interactions between pretreatment and aging (eta p(2) = 0.077, p = 0.033). Non-pretreated and non-aged specimens showed the lowest monoclinic percentage. Hydrothermal aging and 5 years of storage at room temperature increased the monolithic percentage of 3Y-TZ1D(0.25). The highest phase transformation was observed in groups air abraded with 105-mu m alumina particles. Increasing pressure during the air-abrading process increased the content of the monoclinic phase in zirconia surfaces. Significance. Air-abrasion with 30-mu m silica-coated alumina powder can be recommended for pretreatment of 3Y-TZ1D(0.25) and 3Y-TZ1D(0.05). For air-abrasion using alumina powder lower pressure should be used. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Medizin
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• ISSN: 0109-5641
• Sprache: Englisch