title: Fracture Strength of Aged Monolithic and Bilayer Zirconia-Based Crowns.
abstract: The purpose of this study was to evaluate the effect of design and surface finishing on fracture strength of yttria-tetragonal zirconia polycrystal (Y-TZP) crowns in monolithic (1.5 mm thickness) and bilayer (0.8 mm zirconia coping and 0.7 mm porcelain veneer) configuration after artificial aging. Bovine incisors received crown preparation and Y-TZP crowns were manufactured using CAD/CAM technique, according to the following groups (n = 10): Polished monolithic zirconia crowns (PM); Glazed monolithic zirconia crowns (GM); Bi-layer crowns (BL). Crowns were cemented with resin cement, submitted to artificial aging in a chewing simulator (2.5 million cycles/80 N/artificial saliva/37 °C), and tested for fracture strength. Two remaining crowns referring to PM and GM groups were submitted to a chemical composition analysis to measure the level of yttrium after aging. One-way ANOVA and Tukey's test (P = .05) indicated that monolithic zirconia crowns presented similar fracture strength (PM = 3476.2 N ± 791.7; GM = 3561.5 N ± 991.6), which was higher than bilayer crowns (2060.4 N ± 810.6). There was no difference in the yttrium content among the three surfaces evaluated in the monolithic crowns. Thus, monolithic zirconia crowns present higher fracture strength than bilayer veneered zirconia after artificial aging and surface finishing does not affect their fracture strength.
authors.affiliation: Prosthodontics and Periodontology Department, Faculty of Dentistry, University of Campinas (UNICAMP), 13414-903 Piracicaba, SP, Brazil.
authors.forename: Deborah Pacheco
authors.initials: DP
authors.lastname: Lameira
authors.affiliation: Prosthodontics and Periodontology Department, Faculty of Dentistry, University of Campinas (UNICAMP), 13414-903 Piracicaba, SP, Brazil.
authors.forename: Wilkens Aurélio
authors.initials: WA
authors.lastname: Buarque e Silva
authors.affiliation: Prosthodontics and Periodontology Department, Faculty of Dentistry, University of Campinas (UNICAMP), 13414-903 Piracicaba, SP, Brazil.
authors.forename: Frederico
authors.initials: F
authors.lastname: Andrade e Silva
authors.affiliation: Department of Clinical Sciences, Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, ON, Canada M5G 1G6.
authors.forename: Grace M
authors.initials: GM
authors.lastname: De Souza
mesh_terms: D000818:Animals; D002417:Cattle; D019245:Compressive Strength; D003442:Crowns; D017267:Dental Prosthesis Design / Q000379:methods*; D003799:Dental Stress Analysis / Q000379:methods*; D019544:Equipment Failure Analysis; D006244:Hardness; D007180:Incisor / Q000502:physiology*; D013314:Stress, Mechanical; D013718:Tensile Strength; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015040:Zirconium