RESUMO
OBJECTIVES: This study evaluated surface roughness, biaxial flexural strength, and phase transformation of 5Y-PSZ after grinding and polishing with different protocols. MATERIAL AND METHODS: Two commercial 5Y-PSZ, Lava Esthetic (L) and Cercon xt (C), were used and divided into 3 groups: LC and CC represented unpolished control groups; LE and CE were polished with protocol I (EVE DIASYNT® PLUS HP following with EVE DIACERA RA); and LJ and CJ were polished with protocol II (Superfine diamond bur following with Jota ZIR Gloss polishing kit). Surface roughness was evaluated after polishing step-by-step with a contact-type profilometer. After high-gross polishing, the specimens were subjected to biaxial flexural strength test, crystallographic microstructure analysis using an X-ray diffractometer (XRD), and surface micro-topography using scanning electron microscopy (SEM). STATISTICAL ANALYSIS: Surface roughness differences after each step and biaxial flexural strength between groups were evaluated with one-way ANOVA, followed by Bonferroni post-hoc analysis. Changes in surface roughness across four different time points within groups were assessed using one-way repeated measures ANOVA, followed by Bonferroni post-hoc analysis. RESULTS: After high-gross polishing, both polishing protocols showed significantly lower surface roughness than the grinding group (p < 0.05). The LE and CE groups exhibited the highest surface roughness values, which were significant differences from the LJ and CJ groups (p < 0.05). The LE group showed significantly lower biaxial flexural strength compared to the LC group (p < 0.05). However, there was no statistically significant difference in the CE and CJ groups compared to the control group (p > 0.05). Furthermore, all polishing protocols did not change the phase transformation of zirconia. CONCLUSION: Polishing protocol II provided a smoother surface than the protocol I after high-gross polishing, while the biaxial flexural strength of materials remained unaffected.
RESUMO
Objective: The aim of this study was to compare five toothpastes in terms of alteration of surface roughness and colour of red-wine-stained human enamel over time after brushing simulation. Methods: Stained specimens were randomly divided into five groups (n = 8): Oral-B Gum and Enamel (C), ZACT Stain Fighter (ZW), Colgate Optic White Volcanic Mineral (CW), Oral-B 3D White Luxe Fresh Breath (3DW), and Thepthai (TW). The colour and surface roughness of the specimens were measured after brushing simulation for four durations; two weeks, one month, six months, and twelve months. Abrasive particles in toothpaste were inspected under a scanning electron microscope. Results: Surface roughness was increased in the specimens that underwent brushing simulation in all groups (p < 0.05). ZW (6.33 ± 0.98 µm) exerted the most changes in surface roughness for all durations. Other groups showed similar surface roughness at each time point. ΔE00 and ΔL were increased in all groups until twelve months; however, there were no significant differences between C (ΔE00 = 30.17 ± 4.16, ΔL = 38.19 ± 4.34), CW (ΔE00 = 24.25 ± 10.52, ΔL = 31.12 ± 11.00), and TW (ΔE00 = 29.00 ± 3.96, ΔL = 36.68 ± 4.53) at any time period. Moreover, ZW (ΔE00 = 45.6 ± 8.01, ΔL = 53.03 ± 6.71) and 3DW (ΔE00 = 43.6 ± 7.33, ΔL = 51.03 ± 6.47) exhibited a substantial change and were statistically differed from the other groups after four-weeks. Various characteristics of abrasive particles were inspected under SEM. Conclusion: All five toothpastes increased the surface roughness altered the colour of red wine-stained human enamel over time.
