Effects of artificial aging conditions on yttria-stabilized zirconia implant abutments

Author(s)

Basilio, Mariana de Almeida ; Cardoso, Katia Vieira ; Antonio, Selma Gutierrez ; Rizkalla, Amin Sami ; Santos Junior, Gildo Coelho ; Arioli Filho, Joao Neudenir

• Document type: Journal article
• Source: JOURNAL OF PROSTHETIC DENTISTRY; v. 116, n. 2, p. 277-285, AUG 2016.
• Web of Science Citations: 11

Abstract

Statement of problem. Most ceramic abutments are fabricated from yttria-stabilized tetragonal zirconia (Y-TZP). However, Y-TZP undergoes hydrothermal degradation, a process that is not well understood. Purpose. The purpose of this in vitro study was to assess the effects of artificial aging conditions on the fracture load, phase stability, and surface microstructure of a Y-TZP abutment. Material and methods. Thirty-two prefabricated Y-TZP abutments were screwed and tightened down to external hexagon implants and divided into 4 groups (n = 8): C, control; MC, mechanical cycling (1x10(6) cycles; 10 Hz); AUT, autoclaving (134 degrees C; 5 hours; 0.2 MPa); and TC, thermal cycling (10(4) cycles; 5 degrees/55 degrees C). A single-load-to-fracture test was performed at a crosshead speed of 0.5 mm/min to assess the assembly's resistance to fracture (ISO Norm 14801). X-ray diffraction (XRD) analysis was applied to observe and quantify the tetragonal-monoclinic (t-m) phase transformation. Representative abutments were examined with high-resolution scanning electron microscopy (SEM) to observe the surface characteristics of the abutments. Load-to-fracture test results (N) were compared by ANOVA and Tukey test (alpha=.05). Results. XRD measurements revealed the monoclinic phase in some abutments after each aging condition. All the aging conditions reduced the fracture load significantly (P<.001). Mechanical cycling reduced the fracture load more than autoclaving (P=.034). No differences were found in the process of surface degradation among the groups; however, the SEM detected grinding-induced surface flaws and microcracks. Conclusions. The resistance to fracture and the phase stability of Y-TZP implant abutments were susceptible to hydrothermal and mechanical conditions. The surface microstructure of Y-TZP abutments did not change after aging conditions. (AU)

• FAPESP's process: 10/06651-5 - Comparative analysis of the stability of the joint bolted in zirconia abutments over implants after cyclic loading
• Grantee: João Neudenir Arioli Filho
• Support Opportunities: Regular Research Grants