Introduction: The combination of two or more dental alloys in the oral cavity, which are in
contact with saliva, can lead to mutual interactions and the formation of corrosion products.
These products are metal ions that are released into the body and can cause potential
complications for the patient. (Ciszewski at al., 2007) Corrosion is an electrochemical
process where an electric current occurs between metals through an electrolyte. The driving
force of corrosion is the potential difference between these metals. (Milošev, 1994) In such
a case, it is necessary to replace the primary material with another. Additional solution is to
passivate the surface of the primary material. One of the surface passivation techniques is
galvanic gilding, where a gold layer is applied to the material. (Faber, n.d.) Purpose: We
would like to present the technological process of electroplating with the aim of passivating
the surface. The microstructure of the Co-Cr alloy and gold, their bonding and the thickness
of the gilding were checked by stereo, light and scanning electron mictoscope on the samples
of the gilded metal base of the partial prosthesis made of Co-Cr alloy. Work methods: The
theoretical part of the thesis is based on the reviewed domestic and foreign literature.
Literature was searched in libraries and electronic databases. The practical part of the thesis
includes the production of a partial prosthesis with a metal base made of Co-Cr alloy, its
gilding and metallographic analysis of samples of the gilded metal base. We investigated the
microstructure of the gilding, possible defects in the microstructure and its thickness by
stereo, light and scanning electron mictoscope. We wanted to find out if the gold layer is
continuous and compact. We also examined the microstructure of the boundary surface
between the Co-Cr alloy and gold plating. Results: During the metallographic analysis of
the samples, we encountered a defect in the microstructure of the gilded sublingual arch
sample, which looks like porosity. No defects in the microstructure were found on the
interface between the Co-Cr alloy and the gilding. When measuring the thickness of the
gilding, we came to the conclusion that the gilding is uniformly thick in local areas, but the
thickness varies throughout the entire structure. The gilding on the molar clasp is thicker
than on the sublingual arch. Discussion and conclusion: We believe that the defect in the
microstructure of the gilding represents a damaged part of the gilding that occurred during
the surface treatment of the metallographic sample. If the defect occurred during the
technological process of gilding, it represents an uncovered surface of the Co-Cr alloy
structure, which would not prevent the further release of metal ions. The reason for the
deviation in the thickness of the gilding after the construction is in the movement of the
construction during the mixing of the electrolyte during the final gilding of the metal base.
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