Inhalation of respirable crystalline silica dusts (sized between 0.5 and 5.0 micrograms) causes silicosis. Crystalline silica fillers are used in some composites and fine dusts/aerosols generated during high-speed finishing of these materials may be regularly inhaled by clinical dental personnel. Due to the widespread use of composites, the potential of these dusts/aerosols for causing silicosis warrants concern. Six composites were polymerized, then abraded with diamond and carbide finishing burs to produce dusts in a manner simulating the clinical finishing of esthetic veneers. Dusts were collected on 0.8 micron filters using an air sampling pump. Six hundred particles of each dust sample were counted and measured using a light microscope. The respirable fraction of dust particles ranged between 57.2 and 85.7%. The diamond bur created more respirable particles than the carbide bur for each composite tested. The elemental composition of particles of each composite was determined by energy dispersive x-ray analysis. Silicon was detected in amounts ranging from 71-100%. Based on the composition and particle size distribution only, dusts generated during simulated finishing of composite resins containing quartz filler have the potential for causing silicosis in dental personnel.