Rodrigo Alessandretti1, Marcia Borba1, Alvaro Della Bona2. 1. Postgraduate Program in Dentistry, Dental School, University of Passo Fundo, Brazil. 2. Postgraduate Program in Dentistry, Dental School, University of Passo Fundo, Brazil. Electronic address: dbona@upf.br.
Abstract
OBJECTIVE: To evaluate the cyclic contact fatigue resistance and failure mode of ceramics for monolithic and multilayer restorations. METHODS: Ceramic structures (10 mm × 1.8 mm) were fabricated as follows (n = 28): (1) CAD-on- trilayer structure composed of Y-TZP (yttria stabilized tetragonal zirconia polycrystal- IPS e.max ZirCAD) infrastructure, fusion glass-ceramic (IPS e.max CAD Crystall/Connect) and lithium disilicate-based glass-ceramic (IPS e.max CAD); (2) ZFC- bilayer structure composed of Y-TZP infrastructure veneered by a fluorapatite glass-ceramic (IPS e.max Ceram); (3) LDC- monolithic lithium-disilicate glass-ceramic (IPS e.max CAD); and (4) YZW- monolithic Y-TZP (Zenostar Zr Translucent). All ceramics structures were bonded to a dentin analog substrate (G10). Specimens were submitted to cyclic contact fatigue test in a pneumatic cycling machine with 80 N load and 2 Hz frequency in distilled water at 37 °C. Test was interrupted after 104, 105, 5 × 105 and 106 cycles and the presence or absence of failure was recorded. Fatigue data were analyzed using Kaplan-Meier (log rank) and Holm-Sidak tests (α = 0.05). The relationship between the type of crack leading to failure and the experimental group was analyzed using chi-square test (α = 0.05). RESULTS: There was no statistical difference between CAD-on and YZW groups (p = 0.516), which presented the highest survival rates after cyclic loading, followed by ZFC and LDC groups (p < 0.01). There was a significant relationship between type of crack and experimental group (p < 0.001). LDC specimens showed the greatest frequency of radial cracks, while cone cracks were more prevalent for ZFC and CAD-on specimens. SIGNIFICANCE: Monolithic Y-TZP (YZW) showed similar fatigue resistance to CAD-on multilayer specimens, but different failure mode. Monolithic lithium disilicate glass-ceramic (LDC) and Y-TZP conventionally veneered by glass-ceramic (ZFC) showed lower survival time under fatigue.
OBJECTIVE: To evaluate the cyclic contact fatigue resistance and failure mode of ceramics for monolithic and multilayer restorations. METHODS: Ceramic structures (10 mm × 1.8 mm) were fabricated as follows (n = 28): (1) CAD-on- trilayer structure composed of Y-TZP (yttria stabilized tetragonal zirconia polycrystal- IPS e.max ZirCAD) infrastructure, fusion glass-ceramic (IPS e.max CAD Crystall/Connect) and lithium disilicate-based glass-ceramic (IPS e.max CAD); (2) ZFC- bilayer structure composed of Y-TZP infrastructure veneered by a fluorapatite glass-ceramic (IPS e.max Ceram); (3) LDC- monolithic lithium-disilicate glass-ceramic (IPS e.max CAD); and (4) YZW- monolithic Y-TZP (Zenostar Zr Translucent). All ceramics structures were bonded to a dentin analog substrate (G10). Specimens were submitted to cyclic contact fatigue test in a pneumatic cycling machine with 80 N load and 2 Hz frequency in distilled water at 37 °C. Test was interrupted after 104, 105, 5 × 105 and 106 cycles and the presence or absence of failure was recorded. Fatigue data were analyzed using Kaplan-Meier (log rank) and Holm-Sidak tests (α = 0.05). The relationship between the type of crack leading to failure and the experimental group was analyzed using chi-square test (α = 0.05). RESULTS: There was no statistical difference between CAD-on and YZW groups (p = 0.516), which presented the highest survival rates after cyclic loading, followed by ZFC and LDC groups (p < 0.01). There was a significant relationship between type of crack and experimental group (p < 0.001). LDC specimens showed the greatest frequency of radial cracks, while cone cracks were more prevalent for ZFC and CAD-on specimens. SIGNIFICANCE: Monolithic Y-TZP (YZW) showed similar fatigue resistance to CAD-on multilayer specimens, but different failure mode. Monolithic lithium disilicate glass-ceramic (LDC) and Y-TZP conventionally veneered by glass-ceramic (ZFC) showed lower survival time under fatigue.
Authors: Katia R Weber; Daniel E Meneghetti; Paula Benetti; Alvaro Della Bona; Jason A Griggs; Márcia Borba Journal: J Prosthet Dent Date: 2021-09-02 Impact factor: 3.426
Authors: Alvaro Della Bona; Viviane Cantelli; Vitor T Britto; Kaue F Collares; Jeffrey W Stansbury Journal: Dent Mater Date: 2021-01-19 Impact factor: 5.304