Influence of recasting different types of dental alloys on gingival fibroblast cytotoxicity

Statement of problem Surplus alloy from the initial casting is commonly reused with the addition of new alloy. This recasting procedure could affect the cytotoxicity of dental alloys. Purpose The purpose of this in vitro study was to evaluate the effect of repeated casting of high-noble and base metal alloys on gingival fibroblast cytotoxicity. Material and Methods Disk-shaped specimens (5 × 2 mm, n=60) of a high-noble (Au-Pt) and 2 base metal (Ni-Cr and Cr-Co, n=20) alloys were prepared with 100% new alloy and 50%, 65%, and 100% once recast alloy. The elemental composition of specimens was analyzed with X-ray energy-dispersive spectroscopy. Five specimens from each group were conditioned in saline with 3% fetal bovine serum albumin. The conditioning media were analyzed for elemental release with atomic absorption spectroscopy. Cytotoxic effects were assessed on human gingival fibroblast with a 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyl tetrazolium bromide (MTT) colorimetric assay. The data were analyzed with 1-way and 2-way ANOVA and Tukey's HSD multiple comparison test (α-=.05). Results Elemental compositions of Co-Cr and Au-Pt alloys were significantly different among casting protocols. Elemental release of Co-Cr and Ni-Cr alloys was significantly different between new and recast specimens ( P