Journal of Dental Research, Vol 71, 1871-1874, Copyright © 1992 by International & American Associations for Dental Research Online Journals
The effect of using layered specimens for determination of the compressive strength of glass-ionomer cements
H. M. Anstice, J. W. Nicholson and J. F. McCabe
Materials Technology Group, Laboratory of the Government Chemist, Teddington, Middlesex, United Kingdom.
Compressive strength is widely used as the criterion of strength of
glass-ionomer dental cements, despite the difficulties in interpretation of
the findings. With the introduction of light-cured glass-ionomer cements,
which can be used only in thin layers, the question arises of how test
specimens should be prepared for the measurement of compressive strength. A
suggested method has been to prepare test pieces by building them up in
layers, an approach which is examined critically in the current paper. Two
different conventional (acid-base) glass-ionomers were studied with the use
of layered and unlayered specimens of dimensions 6 mm (height) x 4 mm
(diameter) and 12 mm (height) x 6 mm (diameter). While smaller samples gave
the same value of compressive strength as larger specimens, layered
specimens gave significantly lower values of compressive strength for both
sizes. In view of these findings, and since the layered specimens are
tedious to prepare, we conclude that compressive strength is unsatisfactory
as a criterion of strength for light-cured glass-ionomer cements.
