Brushing (TB) has been shown to alter the in vitro cytotoxicity of casting alloys. Objective:  Measure elemental release during and after brushing. Methods: Five dental alloys (n=6), two high-noble (AuPtZn, AuPd) a noble (PdAg), two base-metal (NiCrBe, NiCr), and a Teflon® control were tested. After polishing and cleaning, the alloys were brushed or not in phosphate-buffered saline (pH 7) with or without toothpaste (TP, Ultrabrite) for 48 h. A linear TB machine using Oral B-35 (soft) toothbrushes, a 200 g load, and 90 strokes/min simulated 2 years of TB. Release of elements was measured by atomic absorption spectroscopy during TB and 7 d after transfer to cell-culture medium. Elemental release under different conditions was compared using ANOVA with Tukey analysis (a=0.05). Results: During TB without TP, only the PdAg alloy showed sig. (p<0.05) increased elemental release (Ag: from 0.01 to 0.4 µg/cm2; Pd from 0.2 to 2.0 µg/cm2). TB with TP sig. increased all measured elements from all alloys (vs. TB alone). Most notably, Zn levels reached 90 µg/cm2 for the AuPtZn alloy and 125 µg/cm2 for the PdAg alloy (vs. < 1.0 µg/cm2 Zn for TB alone). Ni levels reached 850 µg/cm2 for the NiCr alloy and 600 µg/cm2 for the NiCrBe alloy (vs. < 10 µg/cm2 Ni for TB  alone). In the week after TB, TB alone sig. increased Zn from the AuPtZn and the PdAg alloys (from 0.05 to 0.1 µg/cm2). TB with TP sig, increased Ni from the NiCr (from 0.02 to 0.5 µg/cm2) and NiCrBe (from 0.01 to 0.3 µg/cm2) alloys.  Conclusions: TB increased elemental release of some elements, but TB with TP consistently increased elemental release from these alloys.  After TB, elemental release was less predictable. Elemental release may be responsible for altered biocompatibility in vitroafter TB. (Supported by Metalor/MCG Biocompatibility Prog.)  

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