Elemental release from casting alloys is critical to alloy biocompatibility.  Brushing (TB) with toothpaste (TP) has been shown to increase the in vitro elemental release of casting alloys. Objective:  Assess the wear of alloys during TB with TP, hopefully relating wear to elemental release and biocompatibility. Methods: Five dental alloys, two high-noble (AuPtZn, AuPd) a noble (PdAg), and two base metal (NiCrBe, NiCr) were tested. After polishing and cleaning, the alloys were brushed in phosphate-buffered saline (PBS, pH 7) with TP (Ultrabrite) for 48 h. Unbrushed alloys were controls.  A linear TB machine using Oral B-35 (soft) toothbrushes, a 200 g load, and 90 strokes/min simulated 2 years of TB. A profilometer (Taylor Hobsen) measured the roughness (Ra) of each specimen (4, 7.5 mm passes across each specimen, 0.5 mm/s, 4001 points/pass).  The average Ra (n=4 specimens/alloy) was compared with unbrushed controls by two-sided t-tests. Results: Ra for the AuPd and PdAg alloys were statistically unchanged by TB with TP (vs unbrushed controls). However, brushing significantly increased (p<0.05) the mean Ra for the AuPtZn, NiCr, and NiCrBe alloys(* in table).  When different alloys were compared after TB (ANOVA, Tukey, a=0.05), only the  

Ra (SD) in µ	AuPtZn*	AuPd	PdAg	NiCr*	NiCrBe*
Unbrushed	0.05 (0.01)	0.05 (0.01)	0.10 (0.02)	0.04 (0.01)	0.07 (0.01)
TB+TP	0.25 (0.06)	0.12 (0.06)	0.10 (0.04)	0.21 (0.04)	1.02 (0.5)

NiCrBe was significantly rougher (higher Ra) than the others (p<0.05). Conclusions:TB with TP may signficantly roughen some alloy types in this in vitro test. Alloys with increases in Ra also previously showed sig. elemental release during TB with TP.  Thus wear may be important to elemental release and biocompatibility of these alloys. (Supported by Metalor/MCG Biocompatibility Prog.)  

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