Effects of palladium addition on emission of mercury vapor from dental amalgam

Abstract

Objectives: The purpose of this investigation was to test the hypothesis that palladium causes a reduction in mercury emission when added to dental amalgam during condensation. Methods: Mercury vapor release was measured in a closed bottle system and an Intraoral Flow device(IOF). Conventional amalgam restorations were modified by addition of various palladium pellets. 1.57 mm diameter palladium pellets with different porosities were fabricated. These pellets were then placed in amalgam restorations using typical condensation and carving procedures. The samples were stored in a closed bottle and mercury measurements were taken from the bottles at 30 min, 1, 3, 5, 24 and 48 h and 7 days after trituration using a Jerome 411 Mercury Vapor Analyzer (Arizona Instrument Corp., Jerome, AZ). The palladium pellets identified as the most effective in mercury vapor reduction were further tested in an IOF device. Data were analyzed by two-way ANOVA followed by Tukey HSD pairwise analysis for significant findings ( α=0.05). Results: The palladium containing amalgams when tested in the closed bottle system yielded significantly lower ( p<0.05) mercury vapor release than the controls. Pellets fabricated with the highest porosity yielded the greatest reduction in overall mercury vapor release. In the IOF device the overall amount of mercury vapor released from the palladium containing amalgams was also significantly less than the control ( p<0.05). Significance: Mercury vapor emission from dental amalgam was greatly reduced by adding palladium pellets to amalgam during condensation. These techniques require only slight modifications of the standard operative procedures.