Novel Approach to Rapid Mercury Analysis in Whole Saliva

Mercury (Hg) is a major component of dental amalgam. While most studies fail to show a link between dental amalgam and systemic diseases, there is a renewed interest in novel approaches allowing for the Hg detection/measurement in clinical settings. Objective: To develop a new miniaturized technology for efficient analysis of Hg in salivary samples, ultimately leading to a method for determining the oral Hg burden of patients at the point of care. Methods: Whole saliva (10.0 ml) was collected from 40 human subjects divided into 4 groups (n=10/group). Groups differed according to amalgam restoration experience: (1) - recently placed restorations; (2) – amalgam restorations removed prior to saliva collection; (3) - more than 5 long standing restorations; (4) - No amalgam restorations. The Hg measurements were made using polystyrene microspheres coated with a turn-on type fluorescent-based mercury sensor chemistry with high selectivity and sensitivity for Hg (method A). This new method was compared with an established method (method B) utilizing the mercury sensor chemistries in solution (Nolan et al. Inorg Chem 2006) Results: Salivary Hg levels exhibited very similar values in the experimental group (method A) and the control group (method B), ranging between 37 and 1484 nM. Student's t-test of the data revealed no significant difference between the miniaturized experimental method (A) and the control method (B) (p=0.134), and a modest correlation between the two methods (R=0.49; p=0.001). Neither measurement methods revealed salivary Hg levels corresponding to dental amalgam restoration experience of the subjects. Conclusion: The data indicate that Hg measurements allowing detection of salivary Hg levels as low as 20 nM can be accomplished employing a nano-technological approach, using chemistries bound to polystyrene microspheres. The method may be of high relevance for patients at risk for high oral Hg exposures. Supported by NIH/NIDCR grant DE17788.