Efeito de diferentes regimes de acabamento e polimento na resistência à flexão e topografia superficial de zircônias monolíticas
Background: The restorations in monolithic zirconia may require adjustments in their structure prior to cementation. Several methods of finishing and polishing are suggested in the literature, however they can promote structural and surface changes of the zirconia, which can affect the mechanical...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/28037 |
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| Resumo: | Background: The restorations in monolithic zirconia may require adjustments in their structure
prior to cementation. Several methods of finishing and polishing are suggested in the literature,
however they can promote structural and surface changes of the zirconia, which can affect the
mechanical strength of the material in the long term. Aim: To investigate in vitro the effect of
different finishing and polishing regimes and low temperature degradation on flexural strength
and surface topography in two types of monolithic zirconia. Method: 300 zirconia bars (Z: ice
zirkon transluzent / Conventional and UT: Prettau Anterior / Ultratransluzent, zirkonzahn, Gais,
Italy) were made in sizes 2.1-1.3x 2.5x10mm, sanded and sintered, (Z: Conventional; UT:
Ultratransluzent), "Finishing and Polishing" - 5 levels (C- Control, B- diamond polishers, Pgrinding with burs, PB- grinding with burs + diamond polishers, PG- grinding with burs +
glaze) and "Degradation" - 2 levels (WithD: autoclave at 127 ° C, 1,7 bar / 24h, without
degradation). The miniflexion resistance test (3 points) was performed, with v: 1mm / min and
500N and 5000N load cells. Two samples from each group were prepared for Scanning Electron
Microscopy (SEM) / X-ray Dispersive Energy Spectrometry (EDS) and Atomic Force
Microscopy (AFM). The mean roughness of each group was evaluated qualitatively. Data were
analyzed by ANOVA (3 factors) and Tukey (5%). Results: The "Zirconia" (p = 0.0000),
"Finishing and Polishing" (p = 0.0000) and "Degradation" factors (p = 0.01) were statistically
significant, ZBD (1670.2 ± 252.73)A
, ZBD (1663.5 ± 216.80)A
and ZB (1654.7 ± 367.79A
) and
the lowest in the UT zirconia, standing out the UTPG group (372.1 ± 56.295)G
. In the SEM it
can be observed that the glaze layer did not cover the whole surface of the zirconia and the
diamond polishers promoted a more uniform surface. The EDS showed higher amount of
yttrium oxide in the UT zirconia and the AFM showed the higher Ra value was found in the
roughened groups, with UT> Z. Conclusion: The most suitable protocol for finishing and
polishing restorations in zirconia is the use of diamond polishers. The grinding followed by
glaze reduced zirconia resistance and the use of the diamond polishers provided a more uniform
surface compared to the other methods. |
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