Little is known of the release of trace elements in vivo from dental implant materials. Conflicting data have been reported in the literature as to the levels of trace elements released and their potential consequences, mainly because of sampling and analytical methodological errors. In this study methods for average concentration levels of Al, Cr, Co, Mo, Ni, Ti, and V in organs were developed using rabbit tissue from an in vivo implantation study. At least 50% of the brain, liver, lung, kidney, and spleen were taken minimizing contamination. The tissue was homogenized by cryogenic milling at LN2 temperature and then freeze-dried. Samples were digested in nitric acid and hydrogen peroxide using microwave energy. Standard reference materials were utilized for quality control. One liver sample was analyzed 10 times to assess the method precision. Absorbance values in blanks, standards, and test samples were measured using a Varian GTA 95 graphite furnace and 875 spectrophotometer. Very satisfactory method precision and quality control were recorded. Low or very low levels of the trace elements were found in the various organs.

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In response to concerns about contamination of human breast milk from silicone gel-filled breast implants, and because silicon levels are assumed to be a proxy measurement for silicone, we compared silicon levels in milk from lactating women with and without implants. Two other sources of infant nutrition, cow's milk and infant formulas, were also analyzed for silicon. The survey took place at the Breast-feeding Clinic at Women's College Hospital in Toronto. A convenience sample of lactating women, 15 with bilateral silicone gel-filled implants and 34 with no implants, was selected. Women with foam-covered or saline implants or with medically related silicone exposures were ineligible. Collection of samples was scrupulously controlled to avoid contamination. Samples were prepared in a class 100 "ultraclean" laboratory and analyzed using graphite furnace atomic absorption spectrophotometry. Silicon levels were analyzed in breast milk, whole blood, cow's milk, and 26 brands of infant formulas. Comparing implanted women to controls, mean silicon levels were not significantly different in breast milk (55.45 +/- 35 and 51.05 +/- 31 ng/ml, respectively) or in blood (79.29 +/- 87 and 103.76 +/- 112 ng/ml, respectively). Mean silicon level measured in store-bought cow's milk was 708.94 ng/ml, and that for 26 brands of commercially available infant formula was 4402.5 ng/ml (ng/ml = parts per billion). We concluded that lactating women with silicone implants are similar to control women with respect to levels of silicon in their breast milk and blood. Silicon levels are 10 times higher in cow's milk and even higher in infant formulas.