Abstract: The present invention provides a mill having an agitator and grinding chamber which is coated with a non-pigmented, abrasion resistant polymer and a method of using this mill to provide substantially pure ground particles. The polymer coating is typically a thermosetting polymer such as polyurethane or an elastomer such as a fluoroelastomer. The polymer coating provides an abrasion resistant layer between the milling media and the agitator as well as between the grinding chamber and the milling media to prevent spalling, thus increasing the purity of the resultant ground material. The agitator mill may optionally include a ceramic gap separator which is typically formed of stacked plates separated a predetermined distance by shims to separate the ground particles from the milling media in the grinder chamber, thus allowing only the ground particles to pass out of the grinding chamber.

Abstract: The present invention provides a vibratory mill having a grinding chamber, preferably coated with an abrasion resistant polymer, the grinding chamber being charged with glass beads having a diameter in the range of about 0.1 mm to about 10.00 mm. There is further provided a method of using this mill to provide substantially pure ground dental filler particles having an average particle size less than the average wavelength of visible light.