Comparison of surface topography and roughness in different yttrium oxide compositions of dental zirconia after grinding and polishing

Abstract

PURPOSE The purpose of this study was to compare the surface roughness, phase transformation, and surface topography of dental zirconia with three different yttrium oxide compositions under same grinding and polishing conditions. MATERIALS AND METHODS Three zirconia disks (IPS e.max ZirCAD LT, MT, MT multi, Ivoclar Vivadent AG, Schaan, Liechtenstein) were selected for experimental materials. Sixty-nine bar-shaped specimens were fabricated as 12.0 × 6.0 × 4.0 mm using a milling machine and glazing was conducted on 12.0 × 6.0 mm surface by same operator. With a custom polishing device, 12.0 × 6.0 mm surfaces were polished under same condition. Surface roughness (Ra[µm]) was measured before grinding (C), after grinding (G), and at every 3 steps of polishing (P1, P2, P3). X-ray diffraction and FE-SEM observation was conducted before grinding, after grinding, and after fine polishing (P3). Statistical analysis of surface roughness was performed using Kruskal-Wallis test and Mann-Whitney-U test was used as a post hoc test (α = .05). RESULTS There were no significant differences of surface roughness between LT, MT, and MM groups. In LT, MT, and MM groups, P3 groups showed significantly lower surface roughness than C groups. X-ray diffraction showed grinding and polishing didn't lead to phase transformation on zirconia surface. In FE-SEM images, growths in grain size of zirconia were observed as yttrium oxide composition increases. CONCLUSION Polished zirconia surface showed clinically acceptable surface roughness, but difference in yttrium oxide composition had no significant influence on the surface roughness. Therefore, in clinical situation, zirconia polishing burs could be used regardless of yttrium oxide composition.

Sintering mode of a translucent Y‐TZP: Effects on its biaxial flexure fatigue strength, surface morphology and translucency

“…Moreover, it was observed that all specimens mainly contained tetragonal phase with no phase transformation for either sintering mode regarding their crystalline composition. The XRD graphs corroborates with a previous study that investigated the same zirconia under different surface conditions, however they did used fast sintering protocols 21 . Another investigation has found 15 wt.% of cubic phase for the same zirconia; however the author crystalized the zirconia using 1500°C for 2 h 22 .…”

“…The XRD graphs corroborates with a previous study that investigated the same zirconia under different surface conditions, however they did used fast sintering protocols. 21 Another investigation has found 15 wt.% of cubic phase for the same zirconia; however the author crystalized the zirconia using 1500 C for 2 h. 22 Other study showed low amounts of cubic phase for other 3Y-TZP materials: 8 wt.% for CEREC Zirconia sintered using a Speed sintering (15 min/2 min/1578 C) and 20 wt.% for inCoris TZI sintered using a conventional protocol (4 h/2 h/1510 C). 13 In addition, the authors found that the zirconia phase composition was influenced by sintering mode, since speed sintered zirconia presented more tetragonal phase (92.1%) than the conventionally sintered (80%).…”

“…However, the effect of these changes on monolithic zirconia's properties remains debatable. 16 Given these aspects, it seems relevant to accordingly analyze 17,18 the effect of different sintering processes on the surface morphology, 18,19,20 phase transformation, [21][22][23] fatigue strength, 24,25 fractographic features 26 and translucency [26][27][28][29][30] of a novel translucent monolithic zirconia. Therefore, the hypotheses of this study were that the Fast sintering mode would negatively influence the: 1) Morphology and microstructure; 2) Mechanical strength; and 3) Translucency parameter of the evaluated zirconia compared to the Standard sintering mode.…”

Comparison of Testing Designs for Flexural Strength of 3Y-TZP and 5Y-PSZ Considering Different Surface Treatment

“…Based on the existing peaks compared with current studies, specimens from 5Y-PSZ showed a cubic phase whereas 3Y-TZP specimens showed a tetragonal structure. Only minimal phase changes for the 3Y-TZP specimens were detected [ 21 , 24 ].…”

Effect of nonthermal argon plasma treatment on the surface properties and phase transformation of zirconia

“…The plasma performance of these applications significantly depends on the experimental parameters, and one of the most important characteristics is the gas species. Conventional plasma sources are limited in their ability to generate gas; therefore, previous studies that experimented with the surface treatment of zirconia only used a few specific gases, including nitrogen, helium, and argon [13,14]. Additionally, the effect of irradiation time and the flow rate of plasma on the zirconia surface remains unclear [15].…”