title: Stray-field imaging and multinuclear magnetic resonance spectroscopy studies on the setting of a commercial glass-ionomer cement.
abstract: A commercial glass-ionomer (Fuji II) was studied using different NMR techniques. 1H and 19F 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 27Al and 29Si MAS and two-dimensional 27Al 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.
authors.affiliation: Departamento de Engenharia de Materiais, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av Rovisco Pais, 1, 1049-001 Lisboa, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pires
authors.forename: Teresa G
authors.initials: TG
authors.lastname: Nunes
authors.forename: Isaac
authors.initials: I
authors.lastname: Abrahams
authors.forename: Geoffrey E
authors.initials: GE
authors.lastname: Hawkes
authors.forename: Cláudia M
authors.initials: CM
authors.lastname: Morais
authors.forename: Christian
authors.initials: C
authors.lastname: Fernandez
mesh_terms: D000535:Aluminum / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D012825:Silicon / Q000737:chemistry
chemical_list: D005899:Glass Ionomer Cements; D000535:Aluminum; D012825:Silicon