Abstract
The biological quality and chemical composition of alloys used in dental practice change during heat treatment. Often the residues of the previous cast are not disposed of but are reused and recycled until consumed. Thus, manufactured dental restorations have modified biological quality and chemical composition, and compromised biocompatibility. The aim of this study was to investigate the influence of repeated casting on the cytotoxicity of the silver-palladium (Ag-Pd) alloy. Our results showed that repeated casting of the Ag-Pd dental alloy affected its biocompatibility by promoting toxicity against transformed fibroblasts in a contact-independent manner. A strong decrease in cell proliferation, induction of senescence and massive cell death were observed in cultures exposed only to a medium previously incubated with dental alloy samples. The obtained data indicated that toxicity mediated by the accumulation of the Ag, Pd, Cu and Zn cations released from the Ag-Pd material was enhanced by recasting. The induction of cell senescence and subsequent apoptotic and necrotic death were accompanied by amplified intracellular production of reactive oxygen and nitrogen species, suggesting their involvement in the cell destruction process. Therefore, compromised biocompatibility after recasting with the Ag-Pd alloy can be the cause of serious local cell destruction, as observed in clinical practice.
Highlights
The biocompatibility of dental alloys used in fixed prosthodontics is a fundamental property in view of the close and permanent contact with oral tissue
To explore the cytotoxic influence of recasting of a frequently used a silver-palladium (Ag-Pd) dental alloy, the mouse fibroblast cell line L929 was selected because these cells simulate the appropriate microenvironment for dental material application and, according to their proliferative potential, provide a valuable setting for the assessment of eventual cytotoxicity
The observed change in phenotype when compared to cells cultivated only in culture medium or in the presence of glass clearly indicated that the presence of certain dental materials promoted the change in cell phenotype typical for differentiation or rapid aging accompanied by the loss of dividing potential
Summary
The biocompatibility of dental alloys used in fixed prosthodontics is a fundamental property in view of the close and permanent contact with oral tissue. The term biocompatibility refers to the material features with respect to their application in medical practice, which must avoid any undesirable local or systemic effects and enable clinically optimal performance [1]. To reach this goal and the most appropriate cellular and tissue response, the potential cytotoxicity as the main element of biocompatibility, needs to be assessed. The ions eluted from the surface of the material are biologically active and dramatically influence cell physiology as a result of interactions with multiple targets [3]
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