Abstract
As a step in evaluating the feasibility of the use of machinable ceramics in dentistry, two machinable ceramics, a mica-containing glass ceramic and a boron nitride-containing aluminum nitride ceramic, along with a control apatite-containing glass ceramic, were examined for surface polishability Using a profiliometer and for machinability employing SEM. Although polishing of the two machinable ceramics with sand paper resulted in rougher surfaces, dental high-speed cutting of the two machinable ceramics produced smooth surfaces with little chipping, as compared with those of the control glass ceramic. It is speculated that the cleavage of dispersed crystals in the matrix phases gave the two machinable ceramics excellent machinability but limited surface polishability. For intra-oral applications of machinable ceramics, we expect that polishability can be improved by modification of their microstructures.
