Title: 0871 - Effect of Processing Method on Chipping Resistance of Zirconia/Glass-Ceramic Bilayers


Erick Lima, University of Sao Paulo
Karina Santos, University of Sao Paulo
Lidia Arashiro, University of Sao Paulo
Carina Tanaka, University of Sao Paulo
Josete Meira, University of Sao Paulo
Paulo Cesar (Presenter)
University of Sao Paulo


Objectives: To evaluate the effect of the processing method (PM) and of the cooling rate (CR) on the edge chipping resistance (Re) of zirconia/glass-ceramic bilayers.

Methods: Bilayered bend bars (n=10) were produced (25mm-long, 4mm-wide, and 2mm-thick). One layer (1mm-thick) was composed of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP, IPS e.max ZirCAD) and the other layer was composed of one of the following leucite-based glass-ceramics: IPS emax Ceram (processed by powder/liquid application followed by sintering) or IPS e.max ZirPress (processed by lost-wax technique followed by hot-pressing). Sintering followed manufacturer’s recommendations, however, the CR of the final glazing cycle varied between slow (S) or fast (F). For S, the specimens were kept in the closed furnace until reaching the glass-transition temperature (Tg=530°C). For F, specimens were removed from the furnace before reaching Tg. Re was obtained using a Vickers indenter coupled to an universal testing machine (0.1mm/min). Ten indentations were performed varying the distance (d) between the edge of the specimen and the indenter (0.1 to 1.0mm). Chipping forces (F, Newtons) were recorded and Re was calculated by averaging all F/d values. Data were analyzed by two-way ANOVA (alpha=0.05).

Results: Considering the same CR, there was no effect of the processing method on Re. S resulted in significantly higher Re values compared to F for specimens processed by powder/liquid application. Re values obtained for hot-pressed specimens were not affected by the cooling rate.

Conclusions: Traditional powder liquid application method of veneering ceramics resulted in similar resistance to chipping compared to hot-pressing. Slow cooling was able to improve the chipping resistance only for veneering layers processed by the traditional method.


Powder/Liquid application Slow 349.7 a 116.4 33
Fast 285.6 b 117.5 40
Injection Slow 298.4 a,b 119.9 40
Fast 263.5 b 107.9 41

This abstract is based on research that was funded entirely or partially by an outside source:
Fapesp Project #2017-11913-8

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE