Journal of Dental Research, Vol 55, 721-729, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Specification test for the solubility and disintegration of dental cements: a critical evaluation of its meaning
A. D. Wilson
The specification test for solubility and disintegration is an essential
screening test for the quality control of certain cement types. No cement
fails it can be considered for use; however, the test has only a limited
clinical significance because it does not give an indication of the
stability of the fully hardened cement matrix either in oral fluids or
water. Instead, it gives a measure of the content of the soluble reaction
intermediate present in cements that are still hardening and where the
matrix has not fully formed. The test relates, therefore, to early
vulnerability to aqueous attack and hardening rate. The period of test is,
in fact, an atypical one and the true extent of the erosion of the cement
matrix is obscured by the presence of soluble reaction intermediates.
Long-term extrapolations cannot be made and so test results for broadly
satisfactory cements within a category cannot be used for valid comparisons
of clinical excellence, and they can be used even less to compare different
cement types with different setting reactions. For example, in general, the
dental silicate cement has a higher solubility and distinegration figure
than the zinc phosphate cement because it contains soluble sodium salt and
hardens more slowly. However, it is more stable under oral conditiont an
indication of the vulnerability of the forming matrix to attack. The test
is not valid when applied to zinc oxide-eugenol cements because the
products of decomposition are either virtually water-insoluble or volatile
and therefore not measured under the conditions of the test. A method is
suggested for overcoming this deficiency. The test needs to be supplemented
by other tests done on fully hardened cements for longer periods of time
and in mediums that can represent oral conditions. One example would be to
stimulate acid conditions developed in stagnation areas. A total estimation
of decomposition products, both soluble and insoluble, is called for rather
than the determination of soluble materials only.
