Effect of sintering programs and surface treatments on monolithic zirconia
Seren Nur Dokuzlu1, Meryem Gülce Subaşı2
1Bornova Oral and Dental Health Center, İzmir, Turkey.
Purpose:
To investigate the effect of sintering programs and surface treatments on surface properties, phase transformation and flexural strength of monolithic zirconia.
Materials And Methods:
Zirconia specimens were sintered using three distinct sintering programs [classic (C), speed (S), and superspeed (SS)] (n = 56, each). One sample from each group underwent scanning electron microscopy (SEM) and grain size analysis following sintering. Remaining samples were divided into five subgroups (n = 11) based on the surface treatments: control (CL), polish (P), glaze (G), grind + polish (GP), and grind + glaze (GG). One sample from each subgroup underwent SEM analysis. Remaining samples were thermally aged. Monoclinic phase volume, surface roughness, and three-point flexural strength were measured. Monoclinic phase volume and surface roughness were analyzed by Kruskal-Wallis and Dunn tests. Flexural strength was analyzed by two-way ANOVA and Weibull analysis. The relationships among the groups were analyzed using Spearman's correlation analysis.
Results:
Sintering program, surface treatment, and sintering × surface treatment (P ≤ .010) affected the monoclinic phase volume, whereas the type of surface treatment and sintering × surface treatment affected the surface roughness (P < .001). Type of sintering program or surface treatment did not affect the flexural strength. Weibull analysis revealed no significant differences between the m and σo values. Monoclinic phase volume was positively correlated with surface roughness in the SGG and SSP groups.
Conclusion:
After sintering monolithic zirconia in each of the three sintering programs, each of the surface treatments can be used. However, for surface quality and aging resistance, G or GG can be recommended as a surface finishing method.
