The accuracy of occlusal cusp height in cast crowns

Despite a good fit at the finish line, the occlusal cusp height decreased about 80 micron in gypsum-bonded cristobalite investments and increased about 40 micron in phosphate-bonded investments. Disks, tested as simulated occlusal portions of cast crowns, produced similar dimensional changes. This finding suggests that the occlusal cusp height is closely related to the thickness of the disk. An asbestos liner used with a gypsum-bonded investment failed to furnish adequate cushioning. The Kaowool liner provided good accuracy to the occlusal portion and finish line of cast complete crowns.