Characterization of the Interface of Palladium Alloys Cast-to Implant Cylinders

Objectives: High-palladium alloys were used as cost effective alternatives of gold alloys, based in two metallurgical systems, Pd-Cu-Ga and Pd-Ga. They are technique sensitive, when are used in different thicknesses. The objective of this study was to characterize the quality of the interface of two commercial palladium alloys cast-to prefabricated implant gold cylinder, when they were cast in two thicknesses. Methods: Specimens were made by cast-to two different palladium alloys (Mentor P, Elementdental and IPSd.SIGN 84, Ivoclar-Vivadent AG) on gold implant cylinders (MW-GPC10, MIS Implants Technologies LTD). As control was used a commercial high-gold alloy (IPSd.SIGN96, Ivoclar-Vivadent) cast-to the same gold cylinders. Two thicknesses for each cast-to alloy were studied, namely 1mm and 2mm. The specimens were prepared metallographicaly and observed in an optical microscope. Electron microprobe analysis and line scanning microanalysis by energy-dispersive X-ray spectrometer were performed to study the relative variations of the elemental compositions. To evaluate the resulted interfaces were used as criteria the maintenance of structure alloys, the existence of distinct boundaries between alloys, the absence of abrupt diffusion of elements, the absence of forming oxide layers or pores within the interface. Results: According to the above mentioned criteria the interface quality of the 2mm cast-to Pd-Ga alloy on the gold cylinder was poor due to high porosity in the interface, the formation of oxide layer and abrupt diffusion of elements, resulting in a non acceptable union. All other combinations independently from the type of the alloy used or/and the cast thickness did not reveal any difference within the interface zone. Conclusion: Under the limitations of the present study, cast-to prefabricated gold cylinders with different type of high-palladium alloys provide acceptable unions, except the combination of Pd-Ga alloy cast-to gold cylinders in 2mm thickness. Part of the project has been funded by the MIS Co.