Influence of recasting different types of dental alloys on gingival fibroblast cytotoxicity
Section snippets
Material and Methods
To compare the cytotoxic effects of surplus metal addition to base and high-noble alloys, Ni-Cr, Co-Cr, and Au-Pt alloys were selected. Manufacturers and composition of the metal alloys used are shown in Table I. Sixty disk-shaped (5 × 2 mm) wax specimens (Thowax Sculpturing Wax; Yeti Dentalprodukte GmbH, Engen, Germany) were prepared. Preparation of sprues, investment, burnout, and castings were done according to the manufacturer's instructions. The base-metal alloys (Co-Cr and Ni-Cr) were
Results
The first aim of this study was to examine the effect of adding various amounts of surplus alloy to Co-Cr, Ni-Cr, and Au-Pt alloys on the metabolic activity of HGF cells. Table II summarizes the results of the 2-way ANOVA, which showed that the effects of alloy type on MTT activity depend on the amount of recast alloy addition (P<.001). Significant results were observed for alloy groups (P<.001) and casting procedures (P<.001), indicating that both alloy type and amount of recast alloy addition
Discussion
Because of improved mechanical properties and lower cost, Co-Cr and Ni-Cr base metal alloys have increasingly replaced gold alloys in the fabrication of fixed metal ceramic restorations. In addition, many dental laboratories combine previously cast metal with new alloy for financial reasons. These casting procedures change the chemical composition, microstructure, physical properties, and cytotoxicity of the alloys.9, 55, 56 The results of this study demonstrated that extract solutions from all
Conclusions
Within the limitations of this study, casting procedures decreased the cobalt content (P=.021) and increased the chromium content (P=.048) of Co-Cr alloys. The increased indium content (P<.001) of Au-Pt alloys did not affect the composition of Ni-Cr alloys. However, recast Ni-Cr alloys released higher amounts of nickel than the NA-100 group (P<.001). The cytotoxic ranking of tested alloys was Ni-Cr>Au-Pt>Cr-Co. Adding recast alloy negatively influenced the cellular activity of all tested alloys
Acknowledgments
The authors acknowledge the Research Commission of Baskent University School of Medicine for funding this research and Prof. Ismail Ercan, the director of the Ankara Nuclear Research and Education Center, for permission to perform the spectrophotometric analysis.
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