Flexural Strength of Monolithic Zirconia after Different Surface Treatments

Abstract

Aim:The purpose of this study was to evaluate the effect of grinding, over-glazing, regrinding, and polishing on flexural strength of monolithic zirconia. Materials and methods:In this in vitro study, 50 bar-shaped zirconia specimens were fabricated and divided into 5 groups (n = 10) of no-treatment control group (C), grinding (G), grinding + glazing (GGl), grinding + glazing + grinding (GGlG), and grinding + glazing + grinding + polishing (GGlGP). A universal testing machine was used to measure the flexural strength. Data were analyzed using the Tukey's HSD test and ANOVA (p < 0.05). Results: There were significant differences between group C and other groups (p < 0.001). Group C showed the highest mean flexural strength among all groups. There was also a significant difference between groups GGlG and GGlGP (p = 0.031), and the latter group showed higher mean flexural strength. There was no significant difference between other groups (p > 0.001). Conclusion:Regrinding does not have a significant effect on flexural strength of monolithic zirconia compared with grinding. Glazing slightly decreased the flexural strength of ground zirconia surfaces, which was not statistically significant. Polishing improved the flexural strength of ground zirconia surfaces; however, their mean flexural strength was significantly lower than that of the control group. Clinical significance: Grinding may lead to significant strength reduction and decrease the durability of zirconia restorations. Therefore, polishing of ground surfaces is suggested while glazing has an adverse effect on the strength.

Effect of Two Brands of Glaze Material on the Flexural Strength and Probability of Failure of High Translucent Monolithic Zirconia

“…Previous studies [27,[31][32][33][34] reporting on the effect of glaze on the flexural strength of Y-TZP did not mention how many surfaces they applied the glaze layer to, only stating that specimens were "glazed according to manufacturer's instructions". If glaze is applied to the compression side of the test specimen, it would potentially increase the flexural strength.…”

“…In this in vitro study, specimens were shaped according to the guidelines provided by ISO 6872:2015 for ceramic materials and glazed only on one surface which underwent tension during flexural strength test to simulate clinical conditions where crowns are glazed on their outer surface. Apart from one other study [31] which used beams to measure the flexural strength, all the others [27,[32][33][34] used the biaxial flexural strength piston-on-threeball method to measure the flexural strength. This makes it problematic to compare our results with theirs.…”

“…Yener et al and Kumchai et al compared different zirconia materials and found that glazing reduced the flexural strength of specimens [31,32]. Asli et al conducted a study to observe the effect of grinding and glazing on pre-sintered zirconia blocks and found that grinding followed by glazing slightly decreased the flexural strength, but the decrease was not statistically significant [33]. In a similar study, the effect of different surface alterations on flexural strength of monolithic zirconia showed that the mean flexural strength of the reglazed group was significantly higher [34].…”

Effect of orthodontic bonding with different surface treatments on color stability and translucency of full cubic stabilized zirconia after coffee thermocycling

“…Monolithic zirconia restorations are superior to porcelain-veneered zirconia restorations in regards to fracture and chipping, [1][2][3] however, their main drawback is low translucency. 1 One suggested strategy to increase translucency is to increase the yttrium oxide content (Y 2 O 3 ) and subsequently the cubic phase.…”

Effect of Different Surface Treatments and Orthodontic Bracket Type on Shear Bond Strength of High-Translucent Zirconia: An In Vitro Study

“…Zirconia restorations were first used as veneer/core bilayer [ 7 ]. However, monolithic zirconia restorations were later introduced to overcome the high frequency of chipping of the veneers, and the problems related to debonding at the zirconia-porcelain interface [ 8 , 9 ]. New types of monolithic zirconia are currently available to achieve favorable esthetics, translucency, and physical properties, and high-translucent (HT) zirconia is commonly used for monolithic zirconia restorations [ 10 ].…”