The invention relates to use of a material containing a polymerizable
monomer or oligomer, the material exhibiting desirable shrinkage
compensation upon polymerization. The material contains an expansion agent
having a cleaving moiety with the capacity to be cleaved or fragmented by
a catalytic reaction, e.g., acid catalysis. The cleavage, by increasing
the number of molecules in the material, causes expansion that
compensates, at least in part, for shrinkage induced by polymerization of
the monomer or oligomer. The expansion agent is capable of providing
compensation such that no more than 0.4%, advantageously no more than
0.2%, volume shrinkage per molar concentration of polymerized monomer
functional groups occurs, where such compensation is performed at
relatively low temperatures of less than 40.degree. C.