Development of metal-resin composite restorative material part 5: Evaluation of the bonding between Ag-Sn particle and 4-META coupling agent of the metal-resin composite

This study evaluated the oxide characteristics on a Ag-Sn particle surface modified by acid and heat in order to understand the bonding mechanism. Nine different Ag-Sn particles including standard Sn, SnO and SnO₂ were evaluated by X-ray Photoelectron Spectroscopy (XPS). The particles were also used for preparing the composite to test the flexural properties following the ISO 4049. A high correlation between flexural strength of the composites and Sn3d binding energy of their filler particles was found. Different oxide forms (SnO and SnO₂) showed different adhesive abilities to bond with 4-META, regarding the difference in flexural strength of the composite. The highest flexural strength composite showed Sn3d binding energy of its filler at 486.4 eV, which was the SnO binding area. This implies that SnO was responsible for a good bond between particle surface and 4-META coupling agent.