Mercury Vapor Release from Dental Amalgam by Restoration Design; a Methods Comparison
Dillingham, Jeffrey S.
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The aim of this investigation was to evaluate mercury vapor release from amalgam restorations of variable size with two collection methods. The Closed Bottle (CB) method is a simple benchtop technique, while the IntraOral Flow (IOF) method is intended for clinical evaluation. Tytin amalgam was triturated and condensed by a single operator into standardized 0, MO and MOD cavities in acrylic tooth #30 in a typodont. Five samples were made for each design and method. For the CB method, a 25-ml glass bottle, sealed with a rubber septum, was used to store the restored teeth. Vapor was extracted with a syringe and analyzed using the Jerome 411 Analyzer at 1, 3, 5, and 24 hours after trituration and then daily until levels fell below the sensitivity range of the instrument. For IOF, PVS impressions were fabricated for each sample tooth within the typodont and connected to the Jerome Meter. Ten-second vapor samples were taken at the same time periods as CB at a flow rate of 800 ml/min. Average mercury vapor levels' were calculated and the data analyzed by ANOVA and Turkey HSD (α=0.05). A significant difference in mercury vapor was found for time and restoration design with a significant time/design interaction for both methods. A significant difference in total mercury released among designs was found for the CB method and for the I-hour IOF readings. Total mercury could not be calculated for I0F by integration under the curve due to the lack of data points. In conclusion, the data support that mercury vapor release varies with restoration size during amalgam setting, but earlier readings are needed to capture total mercury with the IOF method in vivo.