Journal of Dental Research, Vol 59, 1409-1411, Copyright © 1980 by International & American Associations for Dental Research Online Journals
The shear strength of dental porcelain
W. M. Johnston and W. J. O'Brien
The widespread use of porcelain in restorative dentistry is generally due
to its esthetic appearance even though it is brittle. The transverse
strength, or modulus rupture, averages around 108 MPa (16,000 psi) for
aluminous porcelain and 88 MPa (13,000 psi) for feldspathic porcelain. The
tensile strength, as determined by diametral compression, is approximately
29 MPa (4,200 psi) for opaque feldspathic porcelain and 40 MPa (5,800 psi)
for gingival feldspathic porcelain. The compressive strength is reported to
be 340 MPa (50,000 psi) for a feldspathic porcelain. These mechanical
strength properties of dental porcelain confine its use to low
stress-bearing restorations or to those restorations with a metal
substrate.
