Stray-field imaging and multinuclear magnetic resonance spectroscopy studies on the setting of a commercial glass-ionomer cement

resumo

A commercial glass-ionomer (Fuji II) was studied using different NMR techniques. H-1 and F-19 stray-field imaging (STRAFI) were used to monitor the curing kinetics of the cement and two processes were distinguished: the gelation and maturation phases. Characterization of the aluminium and silicon species present in the glass component and cement was performed by conventional Al-27 and Si-29 MAS and two-dimensional Al-27 triple quantum MAS NMR (MQMAS) techniques. Quantification of the aluminium in the glass component and in the cement indicates the leaching of about 32% of the 4-coordinate aluminium, about 100% of the 5-coordinate aluminium and about 41% of the 6-coordinate aluminium, during the setting reaction. It is also shown that the 5-coordinate aluminium is only present in the surface layer created by the acid attack during the cement formation process. In the cement, silicon maintains species with four bridging oxygens after the leaching of tetrahedral (4-coordinate) aluminium. The silicon analysis correlates well with the aluminium determinations. (C) 2004 Kluwer Academic Publishers.

palavras-chave

DENTAL RESIN; AL-27 NMR; ALUMINOSILICATE; H-1; ANGLE

categoria

Engineering; Materials Science

autores

Pires, R; Nunes, TG; Abrahams, I; Hawkes, GE; Morais, CM; Fernandez, C

Grupos

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