Full text
| |
| Author(s): |
Stephanie Francoi Poole
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2024-11-26 |
| Examining board members: |
Renata Cristina Silveira Rodrigues Ferracioli;
Gelson Luis Adabo;
Rossana Pereira de Almeida;
Gabriel Kalil Rocha Pereira
|
| Advisor: | Renata Cristina Silveira Rodrigues Ferracioli |
| Abstract | |
In order to improve the optical characteristics of monolithic zirconia, new pigmentation techniques are developed to meet this need. Thus, the objective of this study was to evaluate the influence of different pigmentation methods on the optical and mechanical properties of monolithic zirconia, as well as the effect of accelerated artificial aging with UV and UV-B lights on these properties. In this study, three groups (n=15) were evaluated according to the different pigmentation methods: Preshade (PS) (single-body pre-pigmented zirconia), Multilayer (ML) (multilayer pre-pigmented zirconia) and White (W) (white zirconia for pigmentation). After sectioning the ceramic blocks, group W was pigmented by the immersion method where the pre-sintered samples were immersed in coloring liquid for 10 seconds for surface pigmentation. In the samples measuring 5x6x1.5mm, microhardness, color, translucency and X-ray diffraction (XRD) were evaluated. In samples with dimensions of 4x30x1.5 mm, surface roughness, flexural strength and modulus of elasticity were analyzed. After fracture of the samples, part was evaluated by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Fracture toughness was evaluated in samples with dimensions of 3x25x4 mm. Mechanical and optical tests were performed before and after accelerated artificial aging, aiming to simulate the intraoral condition. Microhardness data were analyzed by repeated measures ANOVA, while the other data were compared by 2-way ANOVA (α = 5%). ΔE data were compared by Kruskal-Wallis test, while translucency data were analyzed by repeated measures ANOVA and Bonferroni post-test (α = 5%). The results showed that there was a difference between the groups before aging for microhardness (W=ML>PS), surface roughness (PS>ML>W), flexural strength (PS<ML), modulus of elasticity (W<PS) and fracture toughness (PS>ML>W). After aging, there was no difference between the groups for microhardness, modulus of elasticity and fracture toughness, but there was for flexural strength (ML<PS and W) and an increase in surface roughness values for all groups. Comparing before and after aging, there was an increase in microhardness for PS (p=0.003) and a decrease for ML (p=0.032). For flexural strength, there was a decrease in the ML group (p=0.00). For the modulus of elasticity, there was an increase for the W group (p=0.05). For fracture toughness and surface roughness, the groups presented the same behavior. There was a difference between the groups for ΔE (PS>W=ML) (p<0.05). For translucency, there was a difference between the groups (p<0.05) and accelerated artificial aging (p<0.05), with a decrease in translucency for all groups (ML<PS<W). XRD analysis verified that the crystalline structure is the same and does not undergo phase changes in zirconia. All groups presented similar elements in their composition before and after aging according to the EDS analysis, except for group W, which presented a decrease in C and an increase in Zr. And through the qualitative SEM images, an irregular and rough surface was observed after aging. Accelerated artificial aging, as well as the different pigmentation methods, influenced the optical and mechanical properties, except for fracture toughness. (AU) | |
| FAPESP's process: | 20/14729-6 - Influence of low-temperature degradation and different pigmentation methods on the optical and mechanical properties of monolithic zirconia. |
| Grantee: | Stephanie Francoi Poole |
| Support Opportunities: | Scholarships in Brazil - Doctorate |