RESUMEN
Air abrasion of castings for metal ceramic crowns is a routine procedure in ceramics laboratories for cleaning, seating, and preparing casts for porcelain application. This technique can result in damage to the margins of castings. This investigation evaluated the extent and significance of this procedure. Marginal abrasion ranged from 5 to 110 microns. ANOVA, followed by Tukey's post hoc evaluation revealed no difference between abrasives, but significant differences were noted among alloys and margin configurations (p less than 0.05). Marginal loss by alloy was as follows: [Jelenko O] greater than [Olympia = Cameo] greater than [Jelstar] greater than [Genesis II]. Marginal loss by marginal configuration was as follows: [beveled shoulder] greater than [chamfer = shoulder]. Significant marginal damage can occur during air abrasion of dental castings.