DOI: 10.1177/0003702816687572

Authors
da Ana, P. A. ; Krug, F. J. ; Samad, R. E. ; Santos, D. ; Vieira, N. D. ; Zezell, D. M.

Keywords

Laser-induced breakdown spectroscopy; femtosecond LIBS; fs-LIBS; amalgam; dental restoration; mercury;INDUCED BREAKDOWN SPECTROSCOPY; RESTORATIVE DECISION-MAKING; RESIN-BASED COMPOSITE; PERMANENT TEETH; DENTAL AMALGAM; GLASS-IONOMER; LONGEVITY; REPLACEMENT; TOXICOLOGY; MIGRATION

Abstract

In this work the diffusion of mercury and other elements from amalgam tooth restorations through the surrounding dental tissue (dentin) was evaluated using femtosecond laser-induced breakdown spectroscopy (fs-LIBS). To achieve this, seven deciduous and eight permanent extracted human molar teeth with occlusal amalgam restorations were half-sectioned and analyzed using pulses from a femtosecond laser. The measurements were performed from the amalgam restoration along the amalgam/dentin interface to the apical direction. It was possible to observe the presence of metallic elements (silver, mercury, copper and tin) emission lines, as well as dental constituent ones, providing fingerprints of each material and comparable data for checking the consistence of the results. It was also shown that the elements penetration depth values in each tooth are usually similar and consistent, for both deciduous and permanent teeth, indicating that all the metals diffuse into the dentin by the same mechanism. We propose that this diffusion mechanism is mainly through liquid dragging inside the dentin tubules. The mercury diffused further in permanent teeth than in deciduous teeth, probably due to the longer diffusion times due to the age of the restorations. It was possible to conclude that the proposed femtosecond-LIBS system can detect the presence of metals in the dental tissue, among the tooth constituent elements, and map the distribution of endogenous and exogenous chemical elements, with a spatial resolution that can be brought under 100 mu m.

DOI: 10.1021/acs.analchem.6b03766

Authors
Gaubeur, I. ; Krug, F. J. ; Nunes, L. C. ; Sato, R. H.

Keywords

OPTICAL-EMISSION-SPECTROMETRY; TRACE-METAL ANALYSIS; AQUEOUS-SOLUTIONS; QUANTITATIVE-ANALYSIS; MATRIX CONVERSION; PHASE EXTRACTION; DIETHYLDITHIOCARBAMATE COMPLEXES; ELECTRICAL-DEPOSITION; SENSITIVE DETECTION; HEAVY-METALS

Abstract

This work proposes a new development in the use of melted paraffin wax as a new extractant in a procedure designed to aggregate the advantages of liquid phase extraction (extract homogeneity, fast, and efficient transfer, low cost and simplicity) to solid phase extraction. As proof of concept, copper(II) in aqueous samples was converted into a hydrophobic complex of copper(II) diethyldithiocarbamate and subsequently extracted into paraffin wax. Parameters which X-100 concentration, vortex agitation time and affect the complexation and extraction (pH, DDTC, and Triton time) were optimized in a univariate way. The combination of the extraction proposed procedure with laser-induced breakdown spectroscopy allowed the precise copper determination (coefficient of variation = 3.1%, n = 10) and enhanced detectability because of the concentration factor of 18 times. A calibration curve was obtained with a linear range of 0.50-10.00 mg L-1 (R-2 = 0.9990, n = 7), LOD = 0.12 mg L-1, and LOQ = 0.38 mg L-1 under optimized conditions. An extraction procedure efficiency of 94% was obtained. The accuracy of the method was confirmed through the analysis of a reference material of human blood serum, by the spike and recovery trials with seawater, tap water, mineral water, and alcoholic beverages and by comparing with those results obtained by graphite furnace atomic absorption spectrometry.