Surface Chemical Analysis of Hydroxyapatite Compared to Glass Ionomer and Amalgam Materials Used as Retrograde Filling Material in Dentistry

The aim of this study was to analyses the surface chemistry of different materials used as retrograde filling and compare it with bulk chemical analyses reported. Surface analysis carried out using an X—ray Photoelectron Spectrometer (XPS) built by VG Scientific. Samples of HAP, GIC and Amalgam materials used were prepared as Discs of 10 mm diameter. These transferred on to XPS aluminum stubs. XPS spectra were obtained from the wide scan spectrum of amalgam, the following elements are present: tin (23.2%); mercury (6.6%); carbon (19%) and oxygen (51.2%). The wide scan spectrum of GIC the elements present in the surface of the material are: oxygen (41.1%); aluminum (5%); silicon (4.6%); carbon (36.1%); calcium (11.3%); fluorine (2.1%) and sodium (0.T). The XPS spectra were obtained from the wide scan spectrum of Hydroxyapatite the elements present in the surface are: Oxygen (49-4%), Carbon (33-9%), calcium (8-6%), and Phosphorus (8-4%). In conclusion, the chemical XPS analyses of the materials used as retrograde filling, have shown them to vary considerably with respect to bulk chemical composition. Further surface analysis could include narrow scans, manipulation of surface chemistry, coupled with in vitro and in vivo tests and experiments to determine the importance of different surface components on biocompatibility.