Dissertação
Efeito da imersão periódica em soluções limpadoras na rugosidade superficial, porcentagem de variação de massa e resistência flexural de ligas de cobalto-cromo
Fecha
2014-08-22Registro en:
BORSA, Pedro Carlos Cortiana. Co-Cr alloy immersion in cleaning solutions: effects on flexural strength, surface roughness and percentual of variation of mass. 2014. 62 f. Dissertação (Mestrado em Odontologia) - Universidade Federal de Santa Maria, Santa Maria, 2014.
Autor
Borsa, Pedro Carlos Cortiana
Institución
Resumen
The aim of this study was to evaluate the flexural strength, elastic modulus,
mass changes and surface roughness of two cobalt-chromium alloys, before and
after immersions in four cleaning solutions and distilled water (as control). Co-Cr
alloys (Co-Cr®, Dentsply-DeguDent Industria e Comércio, São Paulo, Brasil; and GM
800+®, Dentaurum GmbH & Co KG, Ispringen, Alemanha) were investigated. Fifty
bar specimens (25 x 3 x 0,5 mm) for the flexural test, 50 quadrangular specimens
(10 x 10 x 1 mm) for mass changes evaluation and 35 cylindrical specimens (10 x 1
mm) for surface roughness measurements were obtained by casting. They were
polished by abrasive paper (#240 to #2500) and diamond polishing paste (3μm).
Specimens were randomly divided into 5 groups according the following cleaning,
solutions: pure white vinegar, 0.2% peracetic acid, sodium perborate - Corega
Tabs®, 0.37% sodium hypochlorite and the control, distilled water. Surface
roughness (Ra parameter) was analyzed using a profilometer (Mitutoyo SJ 410,
Mitutoyo Corp, Kanagawa, Japan) before and after 5, 20 e 90 immersions (10 min
each). Ra changes (ΔRa5, ΔRa20 e ΔRa90) were calculated for the different
intervals. Qualitative surface analyses were performed by Scanning Electron
Microscope (JSM 6360 SEM, JEOL). Both alloys, immersed in pure white vinegar,
0.2% peracetic acid, sodium perborate - Corega Tabs®, 0.37% sodium hypochlorite
had similar roughness changes after 90 immersions (ΔRa from -0,012 to 0,022 μm).
There was a significant surface roughening in hypochlorite (ΔRa90= 0,064 μm for
CoCr®; and ΔRa90 = 0,592 μm for GM 800+). The number of immersions influenced
on the roughness changes only in hypochlorite and there were greater changes in
the GM 800+ alloy. After 90 immersions, GM 800+ alloy showed mass lost in the
hypochlorite solution (-0,3%). This alloy presented higher flexural strength after 90
immersions in SH (σF= 1516 MPa in hypochlorite; 1366 MPa in control). However,
there were no elastic modulus changes. CoCr® alloy did not present differences in
the σF or in elastic modulus in any solution. The only solution that damaged the alloy
surface was 0.37% sodium hypochlorite.